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
Image  by Rene Comet USDA

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.

The Radura symple is a green circle with five dashes on the upper half and a solid green do with two green leaves in the center.
The Radura:  Symbol for irradiated foods

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)
  • Shell Eggs
  • 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.


Image by Dean Hochman / CC BY 2.0

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 Additives[4]

Additive Reason for the Additive
Bacteria (probiotics) Thickens and provides flavor to yogurt  and other fermented dairy products 
Beta-carotene Adds artificial coloring to food
Caffeine Acts as a stimulant
Citric acid Increases tartness to prevent food from becoming rancid
Dextrin Thickens gravies, sauces, and baking mixes
Gelatin Stabilizes, thickens, or texturizes food
Modified food starch Keeps ingredients from separating and prevents lumps
MSG Enhances flavor in a variety of foods
Pectin Gives candies and jams a gel-like texture
Polysorbates Blends oil and water and keep them from separating
Soy lecithin Emulsifies and stabilizes chocolate, margarine, and other items
Sulfites Prevent discoloration in dried fruits
Xanthan gum Thickens, emulsifies, and stabilizes dairy products and dressings

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?

Image by Gabriel Lee / CC BY-NC-SA

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


  1. 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.
  2. 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.
  3. 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.
  4. 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
  5. The Issues: Additives. Sustainable Table. http://www.sustainabletable.org/issues/additives/#fn14. Accessed October 10, 2011.
  6. 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.


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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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