presentation for preservation of food

WELCOME TO THE NATIONAL CENTER FOR HOME FOOD PRESERVATION

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Jams & jellies, curing & smoking, so easy to preserve.

The University of Georgia Cooperative Extension has now published a 6th edition of its popular book, So Easy To Preserve. The book was reviewed and updated in 2020. Chapters in the 388-page book include Preserving Food, Canning, Pickled Products, Sweet Spreads and Syrups, Freezing and Drying.

Serving You

The National Center for Home Food Preservation is your source for current research-based recommendations for most methods of home food preservation. The Center was established with funding from the Cooperative State Research, Education and Extension Service, U.S. Department of Agriculture (CSREES-USDA) to address food safety concerns for those who practice and teach home food preservation and processing methods.

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Dry canning raw vegetables is an unsafe practice, peach season has arrived, time to get blueberries in your freezer.

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Unit 1 – Food Safety

1.6 Preserving and Processing Foods

Most of the world’s food supply undergoes some preservation and processing before being marketed. Preserving and processing foods provide many hidden benefits. Each protects consumers in different ways. Food preservation includes handling or treating food to prevent or slow down spoilage. Food processing involves transforming raw ingredients into packaged food, such as cutting whole carrots into baby carrots, canning fruits, and frozen meats. There are numerous benefits to preservation and processing; however, they also pose some concerns. They pose nutritional and sustainability problems. We will discuss this topic throughout the book.

Food Preservation

Food preservation protects consumers from harmful or toxic food, guards against foodborne illnesses, and also protects the flavor, color, moisture content, and nutritive value of food. Fruits and vegetables have their highest vitamin content and flavor when they are fresh from the vine. Freezing them helps to retain the qualities.

A red box of raisins with a few individual raisins

Foods may be preserved in a variety of ways. Some are ancient methods that have been practiced for generations, such as drying fruits, curing, smoking. or salting meats, pickling vegetables, and fermenting dairy products. Others include the use of modern techniques and technology, including drying , vacuum packing , pasteurization , and irradiation . Some people are skeptical about irradiation.

Food Irradiation

Food irradiation is a preservation technology that improves the safety and extends the shelf life of foods by reducing or eliminating microorganisms and insects. Because it’s a process the public is unfamiliar with, many people are skeptical of eating irradiated foods. Like pasteurizing milk and canning vegetables, irradiation can make food safer for the consumer. Food processors began using irradiation more in the last 35 years and the process is considered safe. The FDA, WHO, CDC, and USDA endorse the safety of irradiated food.

Irradiated foods must bear the international symbol for irradiation. Look for the green Radura symbol along with the statement “Treated with radiation” or “Treated by irradiation” on the food label. Bulk foods, such as fruits and vegetables, must be individually labeled or have a label next to the sale container. The FDA does not require those individual ingredients in multi-ingredient foods (e.g., spices) to be labeled. It is important to remember that irradiation is not a replacement for proper food handling practices by producers, processors, and consumers.

Irradiation does not make foods radioactive, compromise nutritional quality, or noticeably change food’s taste, texture, or appearance. We cannot tell if foods are irradiated because the changes are minimal.

We must follow basic food safety rules with irradiated foods because they could still become contaminated with disease-causing microbes. [1]

How Is Food Irradiated?

The three sources of radiation approved for use on foods include:

Gamma rays: emitted from radioactive forms of the element cobalt or of the element cesium. Gamma radiation is used routinely to sterilize medical, dental, and household products and is also used for the radiation treatment of cancer.
X-rays: produced by reflecting a high-energy stream of electrons off a target substance (usually one of the heavy metals) into food. X-rays are also widely used in medicine and industry to produce images of internal structures.
Electron beam (or e- beam): similar to X-rays and is a stream of high-energy electrons propelled from an electron accelerator into food.

What foods are Irradiated ?

The FDA has approved a variety of foods for irradiation in the United States, including:

Beef, Pork, and Poultry
Crustaceans (e.g., lobster, shrimp, and crab) and shellfish (e.g., oysters and scallops)
Fresh Fruits and Vegetables
Seeds for Sprouting (e.g., for alfalfa sprouts)
Spices and Seasonings

Food Processing

Food processing includes the methods and techniques used to transform raw ingredients into packaged food. Workers in this industry use harvested crops or slaughtered and butchered livestock to create products marketed to the public. There are different ways food can be processed, from a one-off product, such as a wedding cake, to a mass-produced product, such as a line of cupcakes packaged and sold in stores.

The Pros and Cons of Food Processing

Food processing has several significant benefits, such as creating products with a much longer shelf life than raw foods. Some processing techniques allow for easier shipment and marketing to corporations. However, there are certain drawbacks. Food processing can reduce the nutritional content of raw ingredients. For example, canning involves heat, which destroys the vitamin C in fruits and vegetables. Also, certain food additives used during processing, such as high fructose corn syrup, can affect consumers’ health. However, the level of added sugar can make a significant difference. Small amounts of added sugar and other sweeteners, about 6 teaspoons a day for women and 9 teaspoons for a man or less, are not considered harmful. [2] However, one 12-ounce can of regular soda has 9.5 teaspoons, which is considered excessive.

Food Additives

If you examine the label for processed food, it is not unusual to see a long list of added materials. These natural or synthetic substances are food additives and there are more than three hundred used during food processing today. The most popular additives are benzoates, nitrites, sulfites, and sorbates, which prevent molds and yeast from growing on food. [3] Food additives are introduced in the processing stage for a variety of reasons. Some control acidity and alkalinity, while others enhance the color or flavor of food. Some additives stabilize food and keep it from breaking down, while others add body or texture. Table 1.1 lists some common food additives and their uses:

Table 1.3 Food Additive s [4]

The Pros and Cons of Food Additives

The FDA works to protect the public from potentially dangerous additives. Passed in 1958, the Food Additives Amendment states that a manufacturer is responsible for demonstrating the safety of an additive before it can be approved. The Delaney Clause that was added to this legislation prohibits the approval of any additive found to cause cancer in animals or humans. However, most additives are considered to be “generally recognized as safe,” a status that is determined by the FDA and referred to as “GRAS.”

The Pros: Food additives are typically included in the processing stage to improve the quality and consistency of a product. Many additives also make items more “shelf stable,” meaning they will last a lot longer on store shelves and can generate more profit for store owners. Additives can also help to prevent spoilage that results from changes in temperature, damage during distribution, and other adverse conditions. In addition, food additives can protect consumers from exposure to rancid products and foodborne illnesses.

The Cons: Food additives aren’t always beneficial, however. Some substances have been associated with certain diseases if consumed in large amounts. For example, the FDA estimates that sulfites can cause allergic reactions in 1 percent of the general population and in 5 percent of asthmatics. Similarly, the additive monosodium glutamate, which is commonly known as MSG, may cause headaches, nausea, weakness, difficulty breathing, rapid heartbeat, and chest pain in some individuals. [5]

Fermented Foods

Fermentation helps preserve foods while also being a part of food processing. The most common fermented foods people eat today are dairy products such as cheese and yogurt. The fermentation process typically involves microorganisms converting the natural sugars in foods to alcohol or acid. Not all microbes are pathogenic and spoil foods. Many foods require the addition of bacteria, mold, or yeast for the food’s typical characteristics. For example, all yogurts have added the bacteria Lactobacillus bulgaricus and Streptococcus thermophilus cultures. (These are also known as probiotics or live active cultures.) The fungus Penicillium roqueforti gives blue cheese its characteristic color and flavor. And, of course, we all know that yeast is needed to make bread. The video below describes the role that these bacteria, fungi, and yeast have in fermentation.

VIDEO : Why Do We Eat Spoiled Foods? By Minute Earth for TED Ed. (3:20 minutes)

Pre- and Probiotics: What’s the Difference?

There has been significant talk about pre- and probiotic foods in the mainstream media. The World Health Organization defines probiotics as live bacteria that confer beneficial health effects on their host. They are sometimes called “friendly bacteria.” The most common bacteria labeled probiotics are lactic acid bacteria (lactobacilli). Fermented foods such as yogurt contain live probiotic “cultures. Prebiotics are indigestible foods, primarily soluble fibers, that stimulate the growth of certain strains of bacteria in the large intestine and provide health benefits to the host. A review article in the June 2008 issue of the Journal of Nutrition concludes that there is scientific consensus that probiotics ward off viral-induced diarrhea and reduce the symptoms of lactose intolerance. [6]

Expert nutritionists agree that more health benefits of pre-and probiotics will likely reach scientific consensus. As the pre-and probiotic manufacturing fields and their clinical study progress, more information on proper dosing and what exact strains of bacteria are potentially “friendly” will become available.

You may be interested in trying some of these foods in your diet. A simple food to try is kefir , a dairy product fermented with probiotic bacteria. Several websites provide good recipes, including http://www.kefir.net/recipes.htm .

Review Questions

Food irradiation. U.S. Food and Drug Administration. https://www.fda.gov/food/resourcesforyou/consumers/ucm261680.htm . Updated January 4, 2018. Accessed January 18, 2018. ↵
Sugar and Carbohydrates. American Heart Association. http://www.heart.org/HEARTORG/GettingHealthy/NutritionCenter/HealthyDietGoals/Sugars-and-Carbohydrates_UCM_303296_Article.jsp# . Updated April 20, 2017. Accessed June 25, 2021. ↵
The Dangers of Food Additives. How Stuff Works. http://health.howstuffworks.com/wellness/food-nutrition/facts/dangers-of-food -additives.htm . Accessed October 5, 2011. ↵
Chemical Cuisine: Learn about Food Additives. Center for Science in the Public Interest. http://www.cspinet.org/reports/chemcuisine.htm . Published 2012. Accessed January 20, 2018 ↵
The Issues: Additives. Sustainable Table. http://www.sustainabletable.org/issues/additives/#fn14. Accessed October 10, 2011. ↵
Farnworth ER. The Evidence to Support Health Claims for Probiotics. J Nutr. 2008; 138(6), 1250S–4S. http://jn.nutrition.org/content/138/6/1250S.long. Accessed September 22, 2017. ↵

Techniques applied to a food to protect it from microbial contamination and the extend shelf-life

A variety of operations by which raw foodstuffs are made suitable for consumption, cooking, or storage.

Food and other products that are produced, processed, distributed, and disposed of in ways that preserve the environment.

A substance that is poisonous

A method of food preservation in which most of the water is removed from a food. Removal of water inhibits the growth of bacteria, yeasts, and mold that spoil the food.

A process by which oxygen levels are reduced in packaged food, limiting the growth of aerobic bacteria or fungi, and preventing the evaporation of flavoring substances.

The process in which packaged and non-packaged foods are treated with mild heat, usually to less than 221 °F (100 °C) to eliminate harmful bacteria and extend shelf life.

Process of exposing foods to ionizing radiation that will improves the safety and extend the shelf life of foods by reducing or eliminating microorganisms and insects.

Any substance that is added to food, either directly or indirectly.

Legislation passed by the U.S. Congress in 1958 that forbids the addition to food any additives shown to be carcinogenic in any species of animal or in humans.

Substances that cause disease. For example, pathogenic bacteria. Pathogens are disease-causing microorganisms.

Beneficial bacteria found found in yogurt and other fermented foods.

A yogurt-like drink made from milk that is fermented with probiotic bacteria.

Introduction to Nutrition and Wellness Copyright © 2022 by Janet Colson; Sandra Poirier; and Yvonne Dadson is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License , except where otherwise noted.

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11: Food Safety Concerns and Future of Our Food

11.6: food preservation.

Food preservation involves preventing the growth of bacteria, fungi (such as yeasts), or other micro-organisms (although some methods work by introducing benign bacteria or fungi to the food), as well as slowing the oxidation of fats that cause rancidity. Food preservation may also include processes that inhibit visual deterioration, such as the enzymatic browning reaction in apples after they are cut during food preparation.

Many processes designed to preserve food will involve a number of food preservation methods. Preserving fruit by turning it into jam, for example, involves boiling (to reduce the fruit’s moisture content and to kill bacteria, etc.), sugaring (to prevent their re-growth) and sealing within an airtight jar (to prevent recontamination). Some traditional methods of preserving food have been shown to have a lower energy input and carbon footprint, when compared to modern methods.

Maintaining or creating nutritional value, texture and flavor is an important aspect of food preservation, although, historically, some methods drastically altered the character of the food being preserved. In many cases these changes have come to be seen as desirable qualities – cheese, yogurt and pickled onions being common examples.

Traditional techniques

New techniques of food preservation became available to the home chef from the dawn of agriculture until the Industrial Revolution.

Drying is one of the oldest techniques used to hamper the decomposition of food products. As early as 12,000 B.C., Middle Eastern and Oriental cultures were drying foods using the power of the sun. Vegetables and fruits are naturally dried by the sun and wind, but “still houses” were built in areas that did not have enough sunlight to dry things. A fire would be built inside the building to provide the heat to dry the various fruits, vegetables, and herbs.

Cooling preserves food by slowing down the growth and reproduction of micro-organisms and the action of enzymes that cause food to rot. The introduction of commercial and domestic refrigerators drastically improved the diets of many in the Western world by allowing foods such as fresh fruit, salads and dairy products to be stored safely for longer periods, particularly during warm weather.

Freezing is also one of the most commonly used processes, both commercially and domestically, for preserving a very wide range of foods, including prepared foods that would not have required freezing in their unprepared state. For example, potato waffles are stored in the freezer, but potatoes themselves require only a cool dark place to ensure many months’ storage. Cold stores provide large-volume, long-term storage for strategic food stocks held in case of national emergency in many countries.

Boiling liquid food items can kill any existing microbes. Milk and water are often boiled to kill any harmful microbes that may be present in them.

Heating to temperatures which are sufficient to kill microorganisms inside the food is a method used with perpetual stews. Milk is also boiled before storing to kill many microorganisms.

Bag of Prague powder #1, also known as “curing salt” or “pink salt”. It is typically a combination of salt and sodium nitrite, with the pink color added to distinguish it from ordinary salt. Salting or curing draws moisture from a substance through a process of osmosis. substances are cured with salt or sugar, or a combination of the two. Nitrates and nitrites are also often used to cure meat and contribute the characteristic pink colour. It was a main method of preservation in medieval times and around the 1700s.

The earliest cultures have used sugar as a preservative, and it was commonplace to store fruit in honey. Similar to pickled foods, sugar cane was brought to Europe through the trade routes. In northern climates without sufficient sun to dry foods, preserves are made by heating the fruit with sugar. “Sugar tends to draw water from the microbes (plasmolysis). This process leaves the microbial cells dehydrated, thus killing them. In this way, the food will remain safe from microbial spoilage.”Sugar is used to preserve fruits, either in an anti-microbial syrup with fruit such as apples, pears, peaches, apricots and plums, or in crystallized form where the preserved material is cooked in sugar to the point of crystallization and the resultant product is then stored dry. This method is used for the skins of citrus fruit (candied peel), angelica and ginger. Also sugaring can be used in jam jellies.

Smoking is used to lengthen the shelf life of perishable food items. This effect is achieved by exposing the food to smoke from burning plant materials such as wood. Smoke deposits a number of pyrolysis products onto the food, including the phenols syringol, guaiacol and catechol. These compounds aid in the drying and preservation of meats and other foods. Most commonly subjected to this method of food preservation are meats and fish that have undergone curing. Fruits and vegetables like paprika, cheeses, spices, and ingredients for making drinks such as malt and tealeaves are also smoked, but mainly for cooking or flavoring them. It is one of the oldest food preservation methods, which probably arose after the development of cooking with fire.

Pickling is a method of preserving food in an edible anti-microbial liquid. Pickling can be broadly classified into two categories: chemical pickling and fermentation pickling. In chemical pickling, the food is placed in an edible liquid that inhibits or kills bacteria and other micro-organisms. Typical pickling agents include brine (high in salt), vinegar, alcohol, and vegetable oil, especially olive oil but also many other oils. Many chemical pickling processes also involve heating or boiling so that the food being preserved becomes saturated with the pickling agent. Common chemically pickled foods include cucumbers, peppers, corned beef, herring, and eggs, as well as mixed vegetables such as piccalilli.

In fermentation pickling, the food itself produces the preservation agent, typically by a process that produces lactic acid. Fermented pickles include sauerkraut, nukazuke, kimchi, surströmming,

Sodium hydroxide (lye) makes food too alkaline for bacterial growth. Lye will saponify fats in the food, which will change its flavor and texture. Lutefisk uses lye in its preparation, as do some olive recipes. Modern recipes for century eggs also call for lye.

Canning involves cooking food, sealing it in sterile cans or jars, and boiling the containers to kill or weaken any remaining bacteria as a form of sterilization. It was invented by the French confectioner Nicolas Appert. By 1806, this process was used by the French Navy to preserve meat, fruit, vegetables, and even milk. Although Appert had discovered a new way of preservation, it wasn’t understood until 1864 when Louis Pasteur found the relationship between microorganisms, food spoilage, and illness.

Foods have varying degrees of natural protection against spoilage and may require that the final step occur in a pressure cooker. High-acid fruits like strawberries require no preservatives to can and only a short boiling cycle, whereas marginal vegetables such as carrots require longer boiling and addition of other acidic elements. Low-acid foods, such as vegetables and meats, require pressure canning. Food preserved by canning or bottling is at immediate risk of spoilage once the can or bottle has been opened.

Figure 11.6.1: Preserved food. Unidentified stacks of home-canned food. Image used with permission (public domain).

Lack of quality control in the canning process may allow ingress of water or micro-organisms. Most such failures are rapidly detected as decomposition within the can causes gas production and the can will swell or burst. However, there have been examples of poor manufacture (underprocessing) and poor hygiene allowing contamination of canned food by the obligate anaerobe Clostridium botulinum, which produces an acute toxin within the food, leading to severe illness or death. This organism produces no gas or obvious taste and remains undetected by taste or smell. Its toxin is denatured by cooking, however. Cooked mushrooms, handled poorly and then canned, can support the growth of Staphylococcus aureus , which produces a toxin that is not destroyed by canning or subsequent reheating.

Food may be preserved by cooking in a material that solidifies to form a gel. Such materials include gelatin, agar, maize flour, and arrowrootflour. Some foods naturally form a protein gel when cooked, such as eels and elvers, and sipunculid worms, which are a delicacy in Xiamen, in the Fujian province of the People’s Republic of China. Jellied eels are a delicacy in the East End of London, where they are eaten with mashed potatoes. Potted meats in aspic (a gel made from gelatine and clarified meat broth) were a common way of serving meat off-cuts in the UK until the 1950s. Many jugged meats are also jellied.

Meat can be preserved by jugging. Jugging is the process of stewing the meat (commonly game or fish) in a covered earthenware jug or casserole. The animal to be jugged is usually cut into pieces, placed into a tightly-sealed jug with brine or gravy, and stewed. Red wine and/or the animal’s own blood is sometimes added to the cooking liquid. Jugging was a popular method of preserving meat up until the middle of the 20th century.

Burial of food can preserve it due to a variety of factors: lack of light, lack of oxygen, cool temperatures, pH level, or desiccants in the soil. Burial may be combined with other methods such as salting or fermentation. Most foods can be preserved in soil that is very dry and salty (thus a desiccant) such as sand, or soil that is frozen. Many root vegetables are very resistant to spoilage and require no other preservation than storage in cool dark conditions, for example by burial in the ground, such as in a storage clamp. Century eggs are created by placing eggs in alkaline mud (or other alkaline substance), resulting in their “inorganic” fermentation through raised pH instead of spoiling. The fermentation preserves them and breaks down some of the complex, less flavorful proteins and fats into simpler, more flavorful ones. Cabbage was traditionally buried in the fall in northern farms in the U.S. for preservation. Some methods keep it crispy while other methods produce sauerkraut. A similar process is used in the traditional production of kimchi. Sometimes meat is buried under conditions that cause preservation. If buried on hot coals or ashes, the heat can kill pathogens, the dry ash can desiccate, and the earth can block oxygen and further contamination. If buried where the earth is very cold, the earth acts like a refrigerator.

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Food Preservation. Authored by : Medical LibreTexts Contributors. Provided by : LibreTexts. Located at : https://med.libretexts.org/Courses/Sacramento_City_College/SCC%3A_Nutri_300_(Coppola)/Chapters/11%3A_Food_Safety_Concerns_and_Future_of_our_Food/11.6%3A_Food_Preservation . License : CC BY-NC-SA: Attribution-NonCommercial-ShareAlike

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Food preservation.

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Presentation on theme: "Food preservation."— Presentation transcript:

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Chapter 18: Food Safety

18.4 Food Preservation

University of Hawai‘i at Mānoa Food Science and Human Nutrition Program

The Food System

The food system is a network of farmers and related operations, including food processing, wholesale and distribution, retail, industry technology, and marketing. The milk industry, for example, includes everything from the farm that raises livestock, to the milking facility that extracts the product, to the processing company that pasteurizes milk and packages it into cartons, to the shipping company that delivers the product to stores, to the markets and groceries that stock and sell the product, to the advertising agency that touts the product to consumers. All of these components play a part in a very large system.

Two important aspects of a food system are preservation and processing. Each provides for or protects consumers in different ways. Food preservation includes the handling or treating of food to prevent or slow down spoilage. Food processing involves transforming raw ingredients into packaged food, from fresh-baked goods to frozen dinners. Although there are numerous benefits to both, preservation and processing also pose some concerns, in terms of both nutrition and sustainability .

Food Preservation

Food preservation protects consumers from harmful or toxic food by limiting the growth of bacteria within food. There are different ways to preserve food. Some are ancient methods that have been practiced for generations, such as curing, smoking, pickling, salting, fermenting, canning , and preserving fruit in the form of jam. Others include the use of modern techniques and technology, including drying, vacuum packing, pasteurization , and freezing and refrigeration. Preservation guards against foodborne illnesses, and also protects the flavor, color, moisture content, or nutritive value of food. We’ll discuss a few of the more common forms of food preservation below, but be aware that there are many others.

Low-Temperature Storage

One of the most common ways food is preserved in the era of electricity is by storing it at low temperatures, either refrigeration (below 40°F/4ºC) or freezing (below 0ºF/-18ºC). The bacteria that cause food to spoil and the ones that can make us sick are unable to grow at these temperatures. However, the bacteria are still there and will begin growing again if the food is put back into warmer temperatures, as happens if you leave it on the counter or if the power to your refrigerator fails.

High-Temperature Treatment

Low temperatures keep bacteria from growing, but high temperatures can actually kill bacteria. This is one reason why you cook many types of food before eating it (apart from enhancing the flavor). This is also why you can boil contaminated water to make it drinkable. There are several different forms of food preservation that use high temperatures to sterilize food. We’ll discuss two: canning and Pasteurization.

In canning, foods are placed into jars or cans and heated to a temperature that destroys any bacteria, often by boiling. The containers are also vacuum sealed to prevent other bacteria from entering after the container cools down. Canning is an important part of the industrial food system, and many people also practice canning at home.

Pasteurization

Pasteurization is an industrial process used to eliminate bacteria in milk or juice. This process was invented by the French chemist Louis Pasteur in 1862. Pasteurization involves exposing liquids to high temperatures for a very brief amount of time. The short exposure keeps the liquid from cooking, reducing changes to taste or texture. The time and temperature used in Pasteurization varies depending on the product, but in the US, for milk, it’s around 158°F (70°C) for 15 seconds. This temperature greatly reduces the number of bacteria in milk but does not kill all of them, which is why milk in the US must remain refrigerated. Many other countries use ultra-high temperature Pasteurization for milk (140°C for 4 seconds), which kills all bacteria, meaning that unopened milk can last for months unrefrigerated.

Dehydration

Drying food is an effective method of food preservation, because bacteria need water in order to live, just like we do. This is possibly one of the earliest forms of food preservation. Sugar and salt may be used to accelerate the dehydration process, as both of these substances draw water out of bacterial cells at high concentrations. Think of a salty piece of beef jerky for an example of dehydration in action.

Fermentation

Fermentation is the process by which some types of bacteria or yeast break down carbohydrates to make ATP under anaerobic conditions. Some types of fermentation produce molecules that are toxic to bacteria. Different fermenting microbes produce different molecules through fermentation, including alcohol, carbon dioxide, and acids. The ethanol in wine, beer, and other alcoholic beverages and the carbon dioxide that causes bread to rise before baking are both products of fermentation. When fermentation is being used as food preservation, the fermentation product is usually lactic acid. The acidity (low pH) of the fermented food inhibits growth of harmful bacteria. You see this in sauerkraut, kimchi, and yogurt.

Food Irradiation: What You Need to Know

Food irradiation is a very modern form of preserving food that is not like any other. Food irradiation (the application of ionizing radiation to food) is a technology that improves the safety and extends the shelf life of foods by reducing or eliminating microorganisms and insects. Like pasteurizing milk and canning fruits and vegetables, irradiation can make food safer for the consumer. The Food and Drug Administration (FDA) is responsible for regulating the sources of radiation that are used to irradiate food. The FDA approves a source of radiation for use on foods only after it has determined that irradiating the food is safe.

Irradiation does not make foods radioactive, compromise nutritional quality, or noticeably change the taste, texture, or appearance of food. In fact, any changes made by irradiation are so minimal that it is not easy to tell if a food has been irradiated.

Why Irradiate Food?

Irradiation can serve many purposes.

Prevention of Foodborne Illness – to effectively eliminate organisms that cause foodborne illness, such as Salmonella and E. coli.
Preservation – to destroy or inactivate organisms that cause spoilage and decomposition and extend the shelf life of foods.
Control of Insects – to destroy insects in or on tropical fruits imported into the United States. Irradiation also decreases the need for other pest-control practices that may harm the fruit.
Delay of Sprouting and Ripening – to inhibit sprouting (e.g., potatoes) and delay ripening of fruit to increase longevity.
Sterilization – irradiation can be used to sterilize foods, which can then be stored for years without refrigeration. Sterilized foods are useful in hospitals for patients with severely impaired immune systems, such as patients with AIDS or undergoing chemotherapy. Foods that are sterilized by irradiation are exposed to substantially higher levels of treatment than those approved for general use.

How Is Food Irradiated?

There are three sources of radiation approved for use on foods.

Gamma rays are emitted from radioactive forms of the element cobalt (Cobalt 60) or of the element cesium (Cesium 137). Gamma radiation is used routinely to sterilize medical, dental, and household products and is also used for the radiation treatment of cancer.
X-rays are produced by reflecting a high-energy stream of electrons off a target substance (usually one of the heavy metals) into food. X-rays are also widely used in medicine and industry to produce images of internal structures.
Electron beam (or e-beam) is similar to X-rays and is a stream of high-energy electrons propelled from an electron accelerator into food.

Is Irradiated Food Safe to Eat?

The FDA has evaluated the safety of irradiated food for more than 30 years and has found the process to be safe. The World Health Organization (WHO), the Centers for Disease Control and Prevention (CDC) and the U.S. Department of Agriculture (USDA) have also endorsed the safety of irradiated food.

The FDA has approved a variety of foods for irradiation in the United States including:

Beef and Pork
Crustaceans (e.g., lobster, shrimp, and crab)
Fresh Fruits and Vegetables
Lettuce and Spinach
Seeds for Sprouting (e.g., for alfalfa sprouts)
Shellfish – Molluscan (e.g., oysters, clams, mussels, and scallops)
Spices and Seasonings

How Will I Know if My Food Has Been Irradiated?

Food Irradiation. U.S. Food and Drug Administration. https://www.fda.gov/food/resourcesforyou/consumers/ucm261680.htm . Updated January 4, 2018. Accessed January 18, 2018. ↵

Nutrition is the sum of all processes involved in how organisms obtain nutrients, metabolize them, and use them to support all of life’s processes.

Sustainability refers to the goal of achieving a world that meets the needs of its present inhabitants while preserving resources for future generations.

Pasteurization is an industrial process that eliminates bacteria in milk or juice by exposing droplets to high temperatures for a very brief amount of time.

The Centers for Disease Control and Prevention (CDC) are the government agency tasked with monitoring illness in the United States. They gather data from public health departments in all 50 states and monitor the data to detect new outbreaks of disease, monitor existing health concerns, and track the success of public health initiatives. The CDC also carries out research and trains public health experts who can be dispatched to control outbreaks of disease. Much of the CDC’s work is focused on infectious disease, but they also track cases of foodborne illness.https://www.cdc.gov/

18.4 Food Preservation Copyright © by University of Hawai‘i at Mānoa Food Science and Human Nutrition Program is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License , except where otherwise noted.

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17.5C: Food Preservation

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Food preservation is the process of treating food to stop or slow down spoilage, loss of quality, edibility, or nutritional value.

Learning Objectives

Describe how food preservation processes stop or slow down food spoilage thus allowing for longer food storage

Preservation usually involves preventing the growth of bacteria, fungi (such as yeasts), and other microorganisms, as well as retarding the oxidation of fats which cause rancidity.

A number of methods of prevention can be used that can either totally prevent, delay, or otherwise reduce food spoilage.
Maintaining or creating nutritional value, texture, and flavor is an important aspect of food preservation.
Preservation : Food preservation is the process of treating and handling food to stop or slow down food spoilage, loss of quality, edibility, or nutritional value and thus allow for longer food storage.
microorganisms : A microorganism or microbe is a microscopic organism that comprises either a single cell (unicellular), cell clusters, or multicellular relatively complex organisms.
food spoilage : Spoilage is the process in which food deteriorates to the point that it is not edible to humans or its quality of edibility becomes reduced.

Food Preservation

Food preservation is the process of treating and handling food to stop or slow down food spoilage, loss of quality, edibility, or nutritional value and thus allow for longer food storage.

Methods of Food Preservation

A number of methods of prevention can be used that can either totally prevent, delay, or otherwise reduce food spoilage. Preservatives can expand the shelf life of food and can lengthen the time long enough for it to be harvested, processed, sold, and kept in the consumer’s home for a reasonable length of time.

Maintaining or creating nutritional value, texture and flavor is an important aspect of food preservation, although, historically, some methods drastically altered the character of the food being preserved. In many cases these changes have now come to be seen as desirable qualities, as with cheese, yogurt, and pickled onions.

Drying is one of the most ancient food preservation techniques, which reduces water activity sufficiently to prevent bacterial growth.

Refrigeration preserves food by slowing down the growth and reproduction of microorganisms and the action of enzymes which cause food to rot.

Freezing is also one of the most commonly used processes for preserving a very wide range of food including prepared foodstuffs which would not have required freezing in their unprepared state.

Vacuum-packing stores food in a vacuum environment, usually in an air-tight bag or bottle. The vacuum environment strips bacteria of oxygen needed for survival, thereby slowing spoiling. Vacuum-packing is commonly used for storing nuts to reduce the loss of flavor from oxidation.

Salting or curing draws moisture from the meat through a process of osmosis. Meat is cured with salt or sugar, or a combination of the two. Nitrates and nitrites are also often used to cure meat and contribute to the characteristic pink color, as well as inhibition of Clostridium botulinum.

Sugar is used to preserve fruits, either in syrup with fruit such as apples, pears, peaches, apricots, plums, or in crystallized form where the preserved material is cooked in sugar to the point of crystallisation and the resultant product is then stored dry. This method is used for the skins of citrus fruit (candied peel), angelica, and ginger. A modification of this process produces glacé fruit such as glacé cherries where the fruit is preserved in sugar but is then extracted from the syrup and sold, the preservation being maintained by the sugar content of the fruit and the superficial coating of syrup. The use of sugar is often combined with alcohol for preservation of luxury products such as fruit in brandy or other spirits. These should not be confused with fruit flavored spirits such as cherry brandy.

Smoking is used to lengthen the shelf life of perishable food items. This effect is achieved by exposing the food to smoke from burning plant materials such as wood. Most commonly subjected to this method of food preservation are meats and fish that have undergone curing. Fruits and vegetables like paprika, cheeses, spices, and ingredients for making drinks such as malt and tea leaves are also smoked, but mainly for cooking or flavoring them. It is one of the oldest food preservation methods, which probably arose after the development of cooking with fire.

Preservative food additives can be antimicrobial. These inhibit the growth of bacteria or fungi, including mold, or antioxidant, such as oxygen absorbers, which inhibit the oxidation of food constituents. Common antimicrobial preservatives include calcium propionate, sodium nitrate, sodium nitrite, sulfites (sulfur dioxide, sodium bisulfite, potassium hydrogen sulfite, etc.), and disodium EDTA. Antioxidants include BHA and BHT. Other preservatives include formaldehyde (usually in solution), glutaraldehyde (kills insects), ethanol, and methylchloroisothiazolinone.

Pickling is a method of preserving food in an edible anti-microbial liquid. Pickling can be broadly categorized into two categories: chemical pickling and fermentation pickling.

Canning involves cooking food, sealing it in sterile cans or jars, and boiling the containers to kill or weaken any remaining bacteria as a form of sterilization. Foods have varying degrees of natural protection against spoilage and may require that the final step occur in a pressure cooker. High-acid fruits like strawberries require no preservatives to can and only a short boiling cycle, whereas marginal fruits such as tomatoes require longer boiling and addition of other acidic elements. Low acid foods, such as vegetables and meats require pressure canning. Food preserved by canning or bottling is at immediate risk of spoilage once the can or bottle has been opened.

Other forms of preservation can include: jellying, jugging, irradiation, pulsed electric field processing, modified atmosphere, high pressure, burial in the ground, and biopreservation.

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Food preservation. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Food_preservation . License : CC BY-SA: Attribution-ShareAlike
Fermented foods. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Fermented_foods . License : CC BY-SA: Attribution-ShareAlike
Boundless. Provided by : Boundless Learning. Located at : www.boundless.com//microbiolo...microorganisms . License : CC BY-SA: Attribution-ShareAlike
fermentation. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/fermentation . License : CC BY-SA: Attribution-ShareAlike
oligodynamic action. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/oligodynamic+action . License : CC BY-SA: Attribution-ShareAlike
carbohydrates. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/carbohydrates . License : CC BY-SA: Attribution-ShareAlike
Fermented foods. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Fermented_foods . License : Public Domain: No Known Copyright
Food spoilage. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Food_spoilage . License : CC BY-SA: Attribution-ShareAlike
bacteria. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/bacteria . License : CC BY-SA: Attribution-ShareAlike
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Food Preservation: Methods and Their Importance

Food is an essential life requirement related to every function our body performs. It is a source of nutritional components like vitamins, minerals, essential oils, and antioxidants which benefit our health in every possible aspect.

But every food has its specific shelf-life and gets spoiled after harvesting or slaughtering. Based on spoilage, foods are; perishable: foods that deteriorate within 1- 5 days and need immediate freezing; semi-perishable: foods that don’t need immediate freezing and can be stored for 3 to 5 months; and non-perishable: foods stored for a much more extended period.

Further processing of foods helps to increase their shelf-life, prevent the growth of microorganisms, and preserve the food’s nutritional value, known as food preservation. The procedure includes altering atmospheric conditions, enzymatic reactions, chemical treatment, and food moisture.

Table of Contents

Methods of Food Preservation

Food preservation is the natural or mechanical action performed on food to elongate its shelf life after harvesting or slaughtering. These procedures can reduce food deterioration by inhibiting microorganisms’ growth, enzymatic reactions, and auto-oxidation.

Preservation by drying, dehydration, and fermentation is the oldest method, and cold treatment, heat treatment, blanching, irradiation, and canning are the modern methods.

Drying Methods

Food preservation by the drying method has been followed for centuries. Drying refers to removing water from a solid compound (meat, fruits, vegetables, and nuts). Sun drying, solar drying, and air drying are the most performed drying methods. In industry, drum drying, spray drying, vacuum drying, freeze drying, bed drying, and convection air drying are also performed. Drying removes food’s moisture and prevents the growth of yeast, bacteria, and mold, which are responsible for damaging food quality.

Dehydration Method

Dehydration removes moisture (water content) from solid or liquid. It differs from drying because the application of artificial heat under a controlled atmosphere is performed. It is also an old method of food preservation. Dehydration makes food lighter and smaller. Dehydrated foods are preferable during trekking and traveling. Example: Mango, Broccoli, Beets, Grapes, Chicken Fish, etc.,

Food Preservation by Fermentation

Preservation by Cold Treatment

Food preservation by cold treatment includes chilling, freezing, and refrigeration.

Chilling is the preservation method where storage of meals occurs in lower temperature, above its freezing point but below atmospheric temperature. The chilling temperature is −1℃ to +8℃, depending upon the variety of food. Chilling helps to preserve salads, pizza, seafood, and dairy products.

In freezing, the preservation of meals occurs by lowering its temperature below its freezing point. Freezing helps to preserve butter, ice cream, milk, nuts, and grains.

Preservation by refrigeration is when the meal’s temperature is maintained between 0℃ and 8℃. Refrigeration helps to preserve jam, jelly, pickle, and sauce.

Food Preservation by Heat Treatment

Sterilization is a preservation method process where all the microorganisms and spores with minimal chances of causing spoilage are destroyed. Two methods do sterilization: i) Physical sterilization (cold sterilization, heat sterilization), ii) Chemical sterilization (gas sterilization, cold chemical sterilization). Meat, fish, cream, soup, and sauce are usually sterilized.

Preservation by Blanching

Blanching is a type of mild-heat treatment (usually on fresh harvest) where exposure of the foods to hot water or steam help to maintain their physical and physiological properties and extend the shelf-life. It is usually performed before freezing, canning, or drying. Hot steam is preferred over hot water or high temperature to avoid the side effects of blanching (protein denaturation, damage to tissue cells). High-temperature treatment can make fruits and vegetables lose their color. So, to avoid that, sodium carbonate or calcium oxide is added to blancher water. Broccoli, fennel, green beans, and asparagus spears are preserved by blanching.

Preservation by Irradiation

Food irradiation is a treatment method that exposes the food to ionizing radicals (x-ray, gamma ray, and electron beam). It helps to reduce the harmful bacteria and parasites which can cause spoilage. Beef, pork, poultry, lettuce, eggs, coffee, fresh fruits and vegetables, and spices are approved for irradiation by FDA.

Food Preservation by Canning

Storing food in containers or jars by hermetically sealing (tightly closed to prevent air from entering) and sterilizing it with heat is canning. Canning prevents the growth of microorganisms and the activity of food enzymes that can spoil food. The containers are first sterilized, and the food is sealed by vacuum packaging. After that, the container is exposed to heat and cooled. Pressure canning, water bath canning, and steam canning are the methods of canning. Meat, dairy products, and sea foods are preserved by canning.

Importance of Food Preservation

Preventing microbial growth: Stored foods become a great nutritional medium for the growth and colonization of microorganisms. Preservation methods remove some growth-promoting components, like moisture, warmth, etc., from the food, making the storage longer.
Preserving nutritional components: Spoilage of foods degrades the quality of food. Applying preservative methods helps to maintain the dietary details of the food. Although some changes occur during preservation, the stored food is still nutritionally dense.
Preventing physical and chemical damage in food: Preservation methods help avoid auto-oxidation and enzymatic reactions that occur in the foods. Heat and moisture can also cause food spoilage, and applying preservation methods can protect from such damage.
Elongating shelf-life: Since food preservation methods help avoid spoilage of foods, they automatically elongate the shelf-life of perishable and semi-perishable foods.
Save money: Time and again, buying food is the most significant area to spend money. Storage of nutrition for a more extended period means having consumable foods for longer. It means less expense in food which can help save cash.

Drawbacks of Food Preservation

Although food preservation is highly advantageous for long-term savings, it also has different drawbacks. Some of the disadvantages of methods of food preservation are as follows:

Adding sugars and salts to preserve food can make the food unsuitable for consumption by people with different health conditions.
Sometimes food preservation can lead to loss of nutrients as chemical and physical states may change after treatment with different preservation methods.
Long-term use of preserved foods can lead to gastrointestinal disorders like gastritis and indigestion.
Handbook of Food Preservation – Cold [Internet]. [cited 2023Jan18]. Available from: http://www.cold.org.gr/library/downloads/Docs/Handbook%20of%20Food%20Preservation.PDF
Prokopov, Tsvetko & Tanchev, Stoyan. (2007). Methods of Food Preservation. 10.1007/978-0-387-33957-3_1.
UGA [Internet]. [cited 2023Feb5]. Available from: https://nchfp.uga.edu/publications/usda/GUIDE01_HomeCan_rev0715.pdf

Diksha Koirala

Diksha Koirala is a recent graduate student in Food Technology. She developed an interest in the relationship between microorganisms and the environment and their impact on the food and food industries. She is sharing her knowledge here to make the world understand microorganisms and the role it plays in our daily life.

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Food preservation basics videos

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Food preservation videos

These short, informational videos provide hands-on demonstrations of food preservation methods, food safety procedures, and how to create and judge 4-H food preservation projects.

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Homemade jerky 101 (3:57)

Food Safety

Home food fermentation and food safety (5:27)

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Reduce risks: safety first! (4:23)

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Unsafe, outdated food preservation methods (5:21)

4-H food preservation projects

4-H food preservation project guidelines (4:52)

Food preservation 4-H project ideas (2:40)

You be the judge: evaluating food preservation 4-H projects (4:57)

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Food Preservation Techniques

Food preservation techniques have led to an increase in the longevity or shelf life of food items by introducing different ways of preserving methods. Its study is not only important in the field of food science, but also in daily lives, to set up food businesses etc.

The methods of food preservation include some inexpensive traditional and modern methods. We can safely retain the food quality or increase the shelf life through the different food preservation methods like drying, freezing, canning, salting etc.

Content: Food Preservation Techniques

Physical methods, chemical methods, definition of food preservation.

Principle of Food Preservation

The principle of food preservation includes prevention against microbial decomposition, prevention of self-decomposing foods, and prevention against the various chemical, physical and mechanical damage of the food.

Prevents or delay of microbial decomposition : It either involves inhibition of microbial growth (microbiostatic) or killing of microorganisms (microbicidal). Food preservation maintains asepsis, which means “keeping out microbes” by eliminating or filtrating microbes. It restricts microbial growth by various methods like chilling, freezing, smoking etc. and destroys microorganisms by methods like pasteurization, irradiation etc.
Prevents self-decomposition of food items : It either involves inactivation of food enzymes by methods like pickling, salting, sugaring etc. or elimination of pro-oxidants by using antioxidants.
Prevents damage caused by physical, chemical and mechanical damage by the factors like rancidity, flavour encapsulation, bruising etc.

Video: Food Preservation Techniques

Food preservation methods include the following objectives:

Ensures the edibility of food by preventing pathogenic organisms or chemicals.
Prevents bacterial and fungal growth in food products.
Keeps the quality, including colour, texture, flavour etc. and nutritive value of the food products remain intact.
Retards the oxidation of fats to reduce rancidity.
Prevents food from discolouration or ageing.
Seals the preserved food to keep away the pathogenic microbes.

Common Methods of Food Preservation

Food preservation technique can be categorized into two classes, namely physical and chemical means of preserving food.

Food can be preserved by physical methods like:

It is also called dehydration method , which removes the moisture content of the food naturally by the sunlight. Drying method was popular from the ancient times, where people used to dry various spices, vegetables and fruits etc. through the effective solar light . We must have heard about the sundried tomato that has been originated from Southern Italy, which is known for its deliciously sweet taste.

In India, also drying method has been used for food products like apple, mango, chillies, herbs, different spices etc. Drying method involves exposure of food items to the direct sunlight on the clean, dry place for up to two weeks or more. Nowadays, an electric dehydrating machine is also used as an artificial method of drying.

It is also called the refrigeration method, which is most commonly used in this modern generation. Chilling is a simple method, which makes the use of cold temperature (1-4 degrees Celsius) to store the food for a few days to a few weeks depending upon the food content, food type etc. The cold temperature holds back the microbial growth, and so minimizes the food spoilage.

Things like food storage, food containers, fridge temperature etc. are the factors which we must keep in mind before refrigeration. The use of sterilized containers, storage of food items on particular shelves, discarding of decayed food and the temperature between 1 to 4 degrees Celsius can increase the food longevity.

It is also called bottling, in which different kinds of canner are used to sterilize the jars and the food material kept in it. Water bath canners are generally used to store high acid foods, and pressure canners are used for low acid foods. In the process of canning, different food items like vegetables, fruits, fish, meat etc. are first processed then stored inside a sterilized jar or can.

Finally, the jars are sealed by a top lid, and it can be labelled with the information like date of processing and the name of the food item. Sir Nicholas Appert was a scientist, who is known as “Father of Canning”.

It is a conventional method of food preservation, which makes the use of smoke released by burning a type of wood . The formaldehyde and the phenolic compounds of the wood add unique flavour to the smoked food items. The smoking method is now generally used for fish and meats. It preserves the food through the antimicrobial properties of the formaldehyde and phenolic compounds and through heating, the food product dries up.

Pasteurization

It is known after the name of a scientist “ Louis Pasteur ” who introduced that the food can be spoiled when exposed to the air. Air contains numerous microbes, which can deteriorate the physiochemical properties of the food. The process of pasteurization makes the use of high heat to destroy or deactivate the pathogenic microorganisms.

Commonly, there are three pasteurization methods known, namely VAT, HTST and UHT. The VAT or LTLT method comes under the category of batch pasteurization, whereas HTST and UHT methods come under the category of flash pasteurization. VAT pasteurizes the food items comparatively at a lower temperature for a long time. Oppositely, HTST and UHT method pasteurize the food items at relatively high temperature for a short time.

HTST or high-temperature short time works under 161 degrees F for 16 seconds, while UHT or ultra-high temperature works under 280-302 degrees F for up to 1-2 seconds. Pasteurized products like milk, cheese, butter, juices etc. have a long shelf life, but once the package is opened, then it must be kept inside the refrigerator .

Food can also be preserved by chemical methods like:

It is a common method of preserving food items by the addition of sugary substances to reduce the moisture content. Sugaring is mostly used for the preservation of fruits like cranberries, mango, apricots etc. commonly called jam. The addition of sugar into the fruits increases sugar concentration, which causes the food item to release its water content and prevents against microbial attack.

Salting is one of the food preservation methods, which principle is very much similar to the method of sugaring. The addition of salt results into the release of water content from the desired food and so prevents against the harmful microorganisms that can make the food unappetizing. Salting can be done in two ways, namely dry and wet curing. In dry curing , the dry salt is added into the food items like fish, meat, chicken etc. to draw water out of it.

Oppositely in wet curing , a salt or brine solution is prepared to keep various vegetables for a longer time by following the canning method. Sugaring and salting are the kinds of food preservation techniques, which need special attention as excessive salt and sugar may cause health risks.

It is one of the ancient time food preservation methods, which can be of two types (fermentation and chemical pickling). The pickling method makes the use of natural preservatives like salt, edible oil, sugar, and spices etc. and chemical preservatives like EDTA. Vegetables like garlic, onion, cucumber, carrot, ginger etc. can be fermented by adding them into a brine solution or vinegar.

Food preservation techniques hold huge importance to keep the food for longer duration without altering the food texture, odour and the nutrient content.

Prevents pathogenic growth : Food preservation technique prevents the microbial growth of E. coli , Salmonella species , Aspergillus species , Mucor species etc. to minimize the chances of food spoilage and food infection. Microbes utilize the food moisture and the nutritive content of the food material to multiply its growth.

As a result, the food material will become inedible for human consumption. Therefore, we need to employ the desired food preservation method to keep the food for a longer time without any microbial attack.

Maintains food quality : Over a period of time, the food products generally degrade by many factors such as a microbial attack, chemical and mechanical damage. It mainly alters food quality by changing the food colour, texture, odour etc. By properly following the safe guides, we can employ various food preservation techniques to retain the food quality along with the intact nutrient content.

Inexpensive method : The traditional methods of food preservation are inexpensive for the setup. Methods like sun drying, pickling, salting, sugaring etc. do not require high capital costs, as the process is natural. It does not need any artificial additives and machinery to increase food longevity.

Therefore, we can conclude that food preservation techniques provide the best way to store different food items. The motive of food preservation is to retard the microbial growth and to extend shelf life of the food by maintaining food safety and food quality.

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Microbiology Notes

Principles of Food Preservation

Table of Contents

What is Food Spoilage?

Unwanted microorganisms can cause food to be contaminated. The contamination is usually natural, but it can also be artificial. Natural contamination is when microorganisms attach to food during its growing stages. For example, Fruits are often contaminated by yeasts, which ferment the fruits’ carbohydrates. Artificial contamination is when food is improperly handled or processed.

Food spoilage refers to a change in the normal state of food. This can be detected by the senses, of taste, smell, and vision. Food changes are dependent on the food’s composition and microorganisms. They result from chemical reactions that relate to the metabolic activities and growth of microorganisms.

Another example is meat, which is primarily made up of protein. The bacteria that is able to digest proteins (proteolytic bacteria), breaks down protein and releases odoriferous compounds such as putrescine or cadaverine. These chemical products are a result of insufficient utilization of amino acids in protein.

A sour flavor can also be caused by food spoilage. Milk that has been kept for too long can turn sour if it is not used soon enough. This is because bacteria that has survived pasteurization can grow in milk and make acid from the carbohydrate, lactose. If the milk is kept at room temperature, it will spoil faster than if it is stored in a refrigerator. The presence of lactic acid and acetic acid as well as other food acids is what causes the milk to taste sour.

What is Food Preservation? / define food preservation

Food preservation is the process of preventing food spoilage, food poisoning, or microbial contamination.

Food preservation is one way to prevent food from microbial growth. We cover the food with lids after it is prepared to protect it from insects and flies. We are protecting the food from any possible infection by insects. This is temporary. Food preservation is used to preserve food for a longer period of time.

Here are some important goals of food preservation.

To prevent microbial contamination.
To kill pathogens.
To minimize food poisoning and food spoilage.

Methods of Food Preservation

These are the main methods for food preservation:

Asepsis is the prevention of microorganisms.
Elimination of microorganisms
Maintain anaerobic conditions in sealed and evacuated containers.
High temperatures are not recommended.
Low temperatures are recommended.
Drying: This includes the binding up of water with hydrophilic colloids or solutes.
Chemical preservatives can be either added or developed by microorganisms.
Irradiation.
Microorganisms can be mechanically destroyed, such as by grinding or high pressures. (Not used in industry).
Combinations of more than one of the methods. A single method is rarely effective. Usually, several methods are combined. Cans are preserved, for example, by heating them in a sealed, evacuated can. Preservatives that are used together have a lower need for intensity than those required to preserve food by just one agency. For sterilization, benzoate and sorbate are used in fruit juices with less heat. Each ingredient can be added at a lower level to catsup, pickles or relishes if it contains sugar, vinegar, and salt. Foods that have been previously sterilized by gamma radiation or antibiotic tylosin need less heat to sterilize than those not treated. In the following chapters, you will find many more examples.

Principles of food preservation – What are the principles of food preservation?

During performing the preservation of foods by the different methods, the following principles are

By keeping microorganisms out (asepsis).
Filtration to remove microorganisms
You can stop the growth or activity of microorganisms by using low temperatures, drying, anaerobic conditions, or chemicals.
You can also kill them by heat or radiation
Food enzymes can be destroyed or inactivated, e.g. by blanching
Antioxidants can be used to prevent or delay chemical reactions.
Prevention of damage caused by insects, animals, or mechanical causes.

Most microorganisms can be controlled using methods that are resistant to chemical reactions or enzymatic activity in food. Autodecomposition can be continued by using low temperatures and drying methods unless you take special precautions. Most vegetables are heated to activate their enzymes before they are frozen.

1. Food preservation by Delay of Microbial Decomposition

Many common methods of food preservation depend not on the destruction or removal of Most common methods for food preservation do not depend on the destruction of microorganisms, but rather on delay in the initiation and hindrance to it once it has started.

Food preservation, i.e. prevention of spoilage, is especially important. This can be achieved by extending the lag phase as much as possible and the phase of acceleration as much as you can. You can do this in many ways.

To introduce as few spoilage organisms (i.e., to reduce the amount of contamination) as possible. The lag phase will be longer if there are fewer organisms.
Avoid the addition of active growing organisms (from logarithmic growth). These organisms could be found in unclean containers, equipment, and utensils, which come into contact with food.
One or more adverse environmental conditions, such as unfavorable food, humidity, temperature, pH, O-R potential, and presence of inhibitors. The more adverse the conditions, the lengthier the delay of the initiation of growth.
Processing methods like heating or radiation that cause actual harm to organisms. Sublethal heat treatments, such as heating or radiation, have shown that bacteria and their spores require better growth conditions than unheated ones. A combination of several methods can delay the initiation and prolong the storage life of food.

The generation time of organisms can be calculated from the growth curve. This is the time between the formation of a cell in a mother cell and the division of that cell into two new cells. The logarithmic growth phase will have the shortest generation time. However, it will vary depending on the environment during growth (e.g., type of food, temperature, O Rpotential, available moisture and presence of inhibitors). As conditions become more favorable, the generation time decreases and becomes longer. Any environmental change that extends the generation time will also increase the food’s shelf life. For example, a drop in temperature will increase the generation time and thus the keeping time. If we start with one cell and it divides every 30 minutes, there will be approximately I million cells within 10 hours. However, only 1,000 cells can be created if the generation takes 60 minutes and 32 cells if it takes 120 minutes. This highlights the importance of not contaminating food with microorganisms in the logarithmic growth phase. When their generation time is shorter, multiplication will occur at its fastest rate.

2. Food preservation by Prevention of Microbial Decomposition

Food spoilage organisms must be killed or removed to prevent microbial decomposition.
However, stopping microorganism multiplication does not prevent their decomposition. Viable organisms and their enzymes can still be active.
In most cases, it is easier to kill microorganisms with smaller numbers than with larger ones. This reaffirms the importance and danger of contamination.
It is especially important to introduce or build up microorganisms that are resistant to the lethal agent, such as heat-resistant bacteria spores, when food is to be heated.
In their logarithmic growth phase, vegetative cells of organisms are less resistant to lethal agents. However, they are more resistant during their later lag or maximal stationary growth phase.

3. Food preservation by Asepsis

Healthy plants and animals have healthy inner tissues that are usually free of microorganisms. If they do exist, it is unlikely that they will cause spoilage.
Microbial decomposition can be delayed or prevented if there is a protective coating around the food.
These coverings include the shells and skins of nuts, fruits, and vegetable skins, husks, and ear corn husks, eggs shells and skin, and membranes, and fats on meat and fish.
Only when the protective layer has been removed or the decomposition has spread to the outer surface, inner tissues can be subject to microorganisms’ decomposition.
Food industries are paying more attention to preventing food contamination, starting from the raw material and ending with the final product.
Food technologists are concerned about the “bioburden” or microorganisms in food. They consider both types and numbers. These types are crucial because they can include spoilage organisms, desirable microorganisms in food fermentations, and even pathogenic microorganisms.
The counts of microorganisms are significant because the more spoilage organisms there are, the more probable food spoilage will be, the more challenging will be the protection of food, and the more probably will be the existence of pathogens.
Bioburden can be caused by contamination, growth, or both.
Many types of food are judged by their microorganisms.
Asepsis is used extensively to package foods. You can choose from loose wrapping or wrapping that prevents contamination, or a sealed can of canned foods. If tightened, it protects the contents from microorganisms.
The dairy industry strives to avoid contamination by microorganisms in the production and processing of milk for market and other purposes. The quality of milk is determined by its bacterial content.
The bioburden (or load) of microorganisms in the canning industry determines the temperature necessary to preserve a food . This is especially true if there are heat-resistant spoilage organisms such as spore-forming thermophiles. After heat treatment, the sealed can stops recontamination.
The meat-packing industry uses sanitary methods for handling, processing, and slaughtering meats to reduce their weight and improve the quality of meat and other meat products.
Controlled food fermentation, such as cheese manufacturing, is more successful if there are fewer competing organisms.

4. Removal Of Microorganisms

Although it is generally not effective for food preservation, the removal of microorganisms can be beneficial under certain conditions. You can remove microorganisms by washing, filtration, centrifugation, clarification, washing, trimming, and/or sedimentation.

Filtration : This is the only method that can completely remove organisms. Filtering the liquid through a sterilized “bacteriaproof”, filter is done using sintered glass, diatomaceous Earth, unglazed porcelain, membrane pad, or another material. The liquid is then forced through the filter by either positive or negative pressure. This technique has been proven to work well with water, fruit juices, and soft drinks.
Sedimentation or centrifugation : Although some microorganisms can be removed by centrifugation or sedimentation, it is generally not very efficient. Although sedimentation can be used to treat drinking water, it is not sufficient by itself. Clarification (or centrifugation) is used to clarify milk. The main purpose of centrifugation is not to remove bacteria, but to remove other suspended materials. However, centrifugation at high speeds removes most spores.
Washing raw foods: While it can help preserve them, washing raw foods may prove to be hazardous under certain conditions. Washing cucumber heads and cabbage heads before they are fermented into sauerkraut or pickles removes most soil microorganisms. This increases the number of beneficial lactic acid bacteria and the overall flora. Fresh fruits and vegetables can be washed to remove soil organisms that might be resistant to heat during canning. It is essential to remove all organisms from food contact equipment. Then, germicidal treatment is performed on the apparatus. If the water is contaminated with spoilage organisms, or if it contains high levels of moisture, washing foods can be hazardous.
Trimming : This is essential from a legal standpoint and can help in food preservation. Even though large quantities of spoilage organisms can be removed this way, it is possible for food to become contaminated. For the production of sauerkraut, it is recommended to trim the outer leaves from cabbage heads.

5. Maintenance Of Anaerobic Conditions

Anaerobic conditions within the container may be a preservative factor for sealed and packaged foods.
Anaerobic conditions can be achieved by a complete fill, the evacuation of any unfilled space (the head space inside a can), and the replacement of the air with carbon dioxide or an inert gas like nitrogen.
Spores from some aerobic sporeformers may be resistant to heat. They can survive in canned foods, but they are unable to germinate in absence of oxygen.
The production of carbon dioxide through fermentation and its accumulation at the surface will make the environment anaerobic and stop the growth of microbes.

what is food preservation?

Food Preservation is when we want to store our foods for future use. We preserve our food through different methods such as freezing, salting, drying, smoking etc. But these methods also affect the taste and quality of food. So preserving our food becomes an important thing.

What are the principles of food preservation?

Food preservation means to keep things edible for long periods of time. There are three ways to preserve food: dehydration, freezing and salting. Dehydration is the process of removing water from foods such as fruits and vegetables which preserves them. Freezing is considered one of the best methods as it retains flavor and nutrients. Salting is used mostly to prevent spoilage when storing perishable items like meat.

What are the different methods of food preservation?

There are several ways to preserve foods, such as canning, freezing, drying, fermenting, salting, smoking, pickling, curing, mummifying, etc. The best way to preserve foods depends on where they were grown, how fresh they were when harvested, and how long they are stored for. For example, some fruits contain natural preservatives and can be eaten without any processing. Other foods require thorough cooking or other treatments before eating. Some foods must be preserved immediately after harvesting. Others can be frozen, dried, or canned.

which methods of food preservation would you use?

The best way to preserve food is through canning. If you don’t have any jars yet, then consider making some for yourself. You’ll find that they’re easy to do at home and that they last forever. They also provide wonderful recipes for future meals.

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April 23, 2024

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Food Preservation Presentation

Huntsville Housing Authority, 212 Seminole Dr, Huntsville, AL 65805

Food Preservation Presentation as part of the Housing Authority’s “Radical Gardening” series. Nutrition and Gardening agents to be speaking the following day.

Address: Huntsville Housing Authority 212 Seminole Dr Huntsville, AL 65805

Contact: Christy Mendoza [email protected] (205) 217-6495

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FOOD PRESERVATION

Jul 23, 2014

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FOOD PRESERVATION. Food preservation frees people from total dependence on geography and climate in providing for their nutritional needs and wants . . Through food preservation, wastage of food can be reduced. As the old saying goes “Waste not, want not”.

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Food preservation frees people from total dependence on geography and climate in providing for their nutritional needs and wants.

Through food preservation, wastage of food can be reduced. As the old saying goes “Waste not, want not”

Ultimately, all natural foods will spoil and even those which have been preserved in one form or another lose their color, flavor, texture, and nutritive value.

Based on theirperish ability, foods may be classified as follow:

Perishable foods Those that spoil readily like milk, fish, meat, poultry, ripe succulent fruits, and leafy vegetables.

Semi-perishable foods Those that can keep for a limited period of time like onions, garlic, eggs, and roots crops.

Relatively nonperishable foods Those that keep for almost an unlimited period of time like rice, dried mature beans, mature corns, and many mature nuts and dry legumes or pulses.

SIGNIFICANCE OF FOOD PRESERVATION Food preservation is also essential from the hygienic stand point. Unless perishable and semi perishable foods are adequately preserved, they form products harmful to the body and are hazard to health.

Food preservation is important from the standpoint of convenience also. The family is greatly helped by the availability of well-preserved foods in convenient forms easily and compactly stored.

CURING INGREDIENTS AND THEIR FUNCTIONS

SALT - is the primary ingredients used in meat curing. It makes up the bulk of the curing mixture because it is not only a good preservative but if provides the most desirable flavor.

Sugar - is a secondary ingredients in the curing formula which counteracts the astringent quality of salt. It enhances the flavor of the product.

Nitrates - are color fixation agents or substances responsible for the development of the proper color in cured meat products.

Ascorbic acid - these substances speed up curing reaction Phosphates- are used to increase the water holding and binding Capacity of cured products.

Vinegar - is added to flavor but it also has some antiseptic value. Therefore aids in prolonging the shelf life of the finished products.

Spices - although the flavoring materials are naturally prescribed in many foodstuff, palatability is further enhanced by the addition of various substances, though lacking in nutritional value, stimulate the flow of digestive secretion thereby materially digestion.

Binders, fillers, emulsifiers - do not cause any radical change in the quality of the product and in some causes actually improved its characteristics.

DETERIORATION AND SPOILAGE OF FOODS To preserve foods, we must cope with their spoilage, and to cope with spoilage, we must know what causes it and how it is brought about.

METHODS OF FOOD PRESERVATION

Drying - is the first known methods of preserving foods. The principle involved is the reduction of the water content in a food to such a degree as to prevent it from spoiling.

The general methods used in draying are: By sunshine- food is usually sliced and spread to dry under the heat of the sun. By artificial heat- food is dried by exposing it to hot air, as in the oven. By air blast- food is dried by means of a fan driven by electricity, alcohol or kerosene.

Smoking This process of preserving is usually used with fish and meat. The material is first salted and exposed to smoke produced by slow-burning sawdust or shavings of one of the Philippine woods, like camachile, guava, or tamarind.

Salting This method is one of the first known and practice here. It is used both with animal and vegetable foods. The salt draws out the water content of the food and enters the tissues, thus making the food firmer and preventing decay.

The two most important methods of salting are: Dry salting- the food is first mixed with salt to remove a large amount of its moisture and then dried. Brining- the food is packed in a container and covered with a solution of salt (brine) until used.

Pickling - is applicable to foods that do not have much taste. Vinegar and condiments serve as preserving materials and give delicious flavor and odor to the food.

The methods of pickling generally used are: Simple pickling- food is prepared, salt and preserved with vinegar and other condiments. These ingredients give the food a better taste and preserve it. Sugar is added to the vinegar when sweet-sour pickle is desired.

Fermented pickling- this is accomplished by curing the food with salt and allowing the latic acid fermentation to develop for a few weeks. The following spices are used in this method- vinegar, pepper, cinnamon, clove, allspice, nutmeg, celery seed, caraway, coriander, turmeric and bay leaves.

Sugar as a preservative - Syrup in a concentrated form acts as a preservatives and food products can be preserved either in dry sugar or syrup which is made by dissolving the sugar in water.

canning - Is a method of heating the food and sealing it in an air-tight container.

The preservation is affected because: • a. The heat destroys chemical agents (enzymes) in the food which are beneficial in causing fruits and vegetables to ripen and meat to become tender, but its continuous action causes over-ripening. • b. Canning destroys microscopic organisms which cause food spoil. • c. Canning prevents organism from getting into the food after it is heated.

Canning is a method that can be used with success with the widest variety of foods. The advantages of canning is that the food can keep long and is always ready to use.

Methods of Canning Boiling water bath method Open kettle method Steamer or oven method Pressure-canner method

Freezing - Is the simplest way to preserve food and the most natural although not the cheapest.

Methods of Food preservation in Freezing • a. Flavor and appearance are unchanged • b. The method is very easy to learn. • c. It is safe. Food spoiling organism present are unable to multiply at freezer temperature.

d. If freezer is done in a regular freezer unit, “it provides you a market in your kitchen, stores whole meals ready to heat, banishes leftovers, and makes a “bank” for pies and cakes”- or what have you. • e. It is a permanent larder of perishables.

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Clifton-based food bank helping community work through food insecurity

Executive director, Jackie Feaster talks about serving the community.

GRAND JUNCTION, Colo. (KJCT) - There are several food pantries and food banks across the Western Slope. One that stands out on the Grand Valley’s east side is the Clifton Christian Community Food Bank.

The CCCFB is now a non-profit that serves thousands of households every year. The food bank, located at 3241 F 1/4 road in Clifton, has drive-thru pantry events and a big event every fourth Saturday of every month.

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Residents say the years of work taken to revive the city, while preserving its history, have paid off.

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In Haverhill, the story of a former factory neighborhood is right on the walls of the brick buildings. Oversize shoe sculptures acknowledge the most famous product of the city’s mills.

Tom Spitalere from the Haverhill Historical Society said Haverhill was the second-largest shoe-producing city in the world at one time. Much of that production happened in the mill buildings that line Washington Street.

In Railroad Square, Savros Dimakis has witnessed the neighborhood change from his diner Mark’s Deli . Both Spitalere and Dimakis said they are happy to see new life come into the mill buildings.

An all-volunteer organization, Team Haverhill has been part of helping change the tone of the neighborhood. They organize public art projects, like murals and the giant shoe sculptures. The group also runs the city’s farmer’s market and hosts street clean-ups. In September, they host their annual River Ruckus festival with a car show, food, bands, and fireworks.

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Food preservation
May 17, 2016 •. 417 likes • 246,649 views. J. Jyotsna Narang. PPT on Food Preservation by Prakhar Aggarwal V A. Education. 1 of 30. Food preservation. Food preservation - Download as a PDF or view online for free.
Food preservation
An overview of food preservation. food preservation, any of a number of methods by which food is kept from spoilage after harvest or slaughter. Such practices date to prehistoric times. Among the oldest methods of preservation are drying, refrigeration, and fermentation. Modern methods include canning, pasteurization, freezing, irradiation, and ...
National Center for Home Food Preservation
Serving You. The National Center for Home Food Preservation is your source for current research-based recommendations for most methods of home food preservation. The Center was established with funding from the Cooperative State Research, Education and Extension Service, U.S. Department of Agriculture (CSREES-USDA) to address food safety ...
1.6 Preserving and Processing Foods
Food Preservation. Food preservation protects consumers from harmful or toxic food, guards against foodborne illnesses, and also protects the flavor, color, moisture content, and nutritive value of food. Fruits and vegetables have their highest vitamin content and flavor when they are fresh from the vine. Freezing them helps to retain the ...
Food Preservation Principles Methods Advances FT505
17 likes • 13,937 views. AI-enhanced title. K. KRATIKA SINGHAM. Principles and Methods of food preservation. Food. 1 of 25. Download now. Food Preservation Principles Methods Advances FT505 - Download as a PDF or view online for free.
11.6: Food Preservation
11.6: Food Preservation. Food preservation involves preventing the growth of bacteria, fungi (such as yeasts), or other micro-organisms (although some methods work by introducing benign bacteria or fungi to the food), as well as slowing the oxidation of fats that cause rancidity. Food preservation may also include processes that inhibit visual ...
Food preservation.
Freezing: Food is stored at temperatures below 0°C. 5 Chemical methods Preservation in a liquid: Food can be preserved in a liquid such as wine, vinegar, lemon juice, alcohol, oil, brine. Salting: this method prevents bacterial growth by reducing water activity (bacteria don't reproduce without moisture) Sugaring: food is cooked with sugar.
Food Preservation
Food preservation consists of the application of science-based knowledge through a variety of available technologies and procedures, to prevent deterioration and spoilage of food products and extend their shelf-life, while assuring consumers a product free of pathogenic microorganisms. Shelf-life may be defined as the time it takes a product to decline to an unacceptable level.
PPT
Presentation Transcript. DEFINITION • High-pressure processing (HPP) is a "non thermal" food preservation technique that inactivates harmful pathogens and vegetative spoilage microorganisms by using pressure rather than heat to effect pasteurization. HPP utilizes intense pressure (about 400-600 MPa) at chilled or mild process ...
18.4 Food Preservation
18.4 Food Preservation University of Hawai'i at Mānoa Food Science and Human Nutrition Program. The Food System. The food system is a network of farmers and related operations, including food processing, wholesale and distribution, retail, industry technology, and marketing. The milk industry, for example, includes everything from the farm ...
17.5C: Food Preservation
Key Terms. Preservation: Food preservation is the process of treating and handling food to stop or slow down food spoilage, loss of quality, edibility, or nutritional value and thus allow for longer food storage.; microorganisms: A microorganism or microbe is a microscopic organism that comprises either a single cell (unicellular), cell clusters, or multicellular relatively complex organisms.
Food Preservation: Methods and Their Importance
Chilling helps to preserve salads, pizza, seafood, and dairy products. In freezing, the preservation of meals occurs by lowering its temperature below its freezing point. Freezing helps to preserve butter, ice cream, milk, nuts, and grains. Preservation by refrigeration is when the meal's temperature is maintained between 0℃ and 8℃.
Food preservation basics videos
These short, informational videos provide hands-on demonstrations of food preservation methods, food safety procedures, and how to create and judge 4-H food preservation projects.After you have viewed a video, please take this short survey about our presentations.Food preservation methodsFood preservation methods: explore the options (5:06)
Food Preservation Techniques
Definition of Food Preservation. Food preservation can define as the process through which one can store the food products for l onger period of time by employing different ways of food preserving techniques like, drying, salting, sugaring, freezing, canning etc. Food preservation is a branch of science, which targets food edibility and quality ...
Food preservation
2. Definition • Food preservation can be defined as the science that deals with the process of prevention of spoilage of food, thus allowing it to be stored in a fit condition for future use. ASTHA K. PATEL 2. 3. • Preservation of food increase the shelf life of the food.
Food Preservation PowerPoint and Google Slides Template
Food management experts, educators, and food preservation experts can utilize this impressive PPT to explain the importance of food preservation. You can also highlight the objectives, techniques, and principles of food preservation. Moreover, you can convey how to use household substances to preserve food for a long.
PPT
Food preservation methods1-Physical methods 2-Chemical methods 3-Biopreservation. Food processing All the operations by which raw foodstuffs (animal and plant tissue) converted into forms that • will not spoil as quickly as the fresh, whole foods (raw materials) from which they were made • is convenient and practical to consume. • includes basic preparation of food, alteration of a food ...
Food Preservation PowerPoint Template
Food Contamination. Download our Food Preservation PPT template to demonstrate the procedure of treating and handling food to slow down spoilage without affecting its edibility and nutritional value. Food management experts can leverage this entirely editable deck to portray the tried and tested measures for preventing the development of ...
Principles Of Food Preservation
Food preservation is the process of preventing food spoilage, food poisoning, or microbial contamination. Food preservation is one way to prevent food from microbial growth. We cover the food with lids after it is prepared to protect it from insects and flies. We are protecting the food from any possible infection by insects.
Food Preservation Presentation
Food Preservation Presentation as part of the Housing Authority's "Radical Gardening" series. Nutrition and Gardening agents to be speaking the following day. Address: Huntsville Housing Authority 212 Seminole Dr Huntsville, AL 65805. Contact: Christy Mendoza [email protected] (205) 217-6495
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Presentation Transcript. Food preservation frees people from total dependence on geography and climate in providing for their nutritional needs and wants. Through food preservation, wastage of food can be reduced. As the old saying goes "Waste not, want not".
Clifton-based food bank helping community work through food insecurity
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PDF Mastering Home Food Preservation Educators and Gauge Testers: April 22
mastering home food preservation educators and gauge testers: april 22, 2024 . lake benton warren laporte starke pulaski white 00 fulton cass lagrange steuben elkhart dekalb allen wayne franklin noble grant henry carroll clinton boone howard tipton montg. parke vigo clay owen sullivan greene knox pike marion morgan ripley
NCUA Board Member Tanya Otsuka Statement on the Advance Notice of
Thank you, Kelly and Matt, for your presentation and all the staff's work on this ANPR. Sound record retention practices, although not a topic often discussed, are critical to ensuring the continuity and longevity of credit unions and the credit union system. ... Records Preservation Program. As Prepared for Delivery on April 18, 2024. Thank ...

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Food Preservation: Methods and Their Importance

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Principles of Food Preservation

What is Food Spoilage?

What is Food Preservation? / define food preservation

Methods of Food Preservation

Principles of food preservation – What are the principles of food preservation?

1. Food preservation by Delay of Microbial Decomposition

2. Food preservation by Prevention of Microbial Decomposition

3. Food preservation by Asepsis

4. Removal Of Microorganisms

5. Maintenance Of Anaerobic Conditions

what is food preservation?

What are the principles of food preservation?