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U.S. Department of Health and Human Services


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List of Terms: A

Return to Comprehensive List of Terms


Did You Know?


Acidification is the result of food fermentation. Fermentation is a natural process where acids are produced by lactic acid bacteria to make cheese, pepperoni, beer, and wine, for example.




A technology used by processors to preserve foods by adding acids and rendering food safe from harmful bacteria.

Food Safety Implication: During processing, the proper pH (the measure of acidity, less than 7, or alkalinity, greater than 7, of a solution) must be maintained in order to prevent the growth of harmful bacteria. Most foodborne bacteria can't grow at pH levels below 4.6. Acidification is one way to maintain safe pH levels and keep various foods safe from harmful bacteria. (Also see pH.)

How It Works: There are 2 ways foods are acidified:

  1. Acid is added to foods as a chemical.
  2. Specific microorganisms like bacteria or yeast are added to foods. These microorganisms will, in turn, produce acid. This is known as fermentation, a process used to make certain foods safer.

Some Common Acidulents and Some of Their Corresponding Foods:

  • Acetic Acid (vinegar, salad dressing)
  • Citric Acid (candy, orange juice)
  • Phosphoric Acid (cola soda)
  • Proprionic Acid (swiss cheese)
  • Lactic Acid (yogurt, pepperoni, sauerkraut)
 Did You Know?

Without food additives, bread would easily mold, salt would lump, ice cream would separate into icy crystals, and marshmallows would harden into bite-sized rocks.

Some common food additives are salt, baking soda, vinegar, and various spices. You can find out which additives have been added to retail foods by checking the ingredient label on the packaging.

Any substance that is added to food and affects the food's characteristics.

Are food additives necessary and are they safe?

Yes, food additives are necessary. Without them, food spoilage, food costs, and the loss of food to pests would be higher. FDA evaluates all food additives for safety before they are allowed in foods and has found them to be safe and effective in the quantities in which they are consumed in foods.

Food Safety Implication: Additives are used in foods during processing to prevent food spoilage, reduce bacterial growth, and thus help prevent foodborne illness.

Two Types of Food Additives:

  1. Direct Additives - These additives are intentionally added to food for a specific purpose. Some examples include:
    • Preservatives - Prevent foods from spoiling.
    • Sweeteners and Flavorings - Protect flavor or add a specific flavor or sweetness.
    • Artificial and Natural Colorings - Make foods look brighter and more attractive.
    • Nutritional Supplements - Improve the nutritional value of foods by adding vitamins or minerals.

  2. Indirect Additives - These substances can become part of the food in trace amounts due to packaging, storage, or handling. For instance, minute amounts of packaging substances may find their way into foods during storage. Food packaging manufacturers must prove to the Food and Drug Administration (FDA) that all materials coming in contact with food are safe before they are permitted for use in such a manner.
For antibacterial household cleaning products to work effectively, they must remain in contact with the surface for a specified amount of time. The amount of time varies from product to product. Read and follow product label directions.

> Antibacterial (also known as Antimicrobial)
A general term that describes a product that kills or inhibits the growth of bacteria in foods or on inanimate surfaces or hands.

Food Safety Implication: Antibacterial house- hold cleaning products kill bacteria on surfaces, such as cutting boards and counter- tops. Personal cleansing products kill germs on hands. Antibacterial products help reduce the possibility of cross-contamination.

In the case of foods, salt is antibacterial and is used as a direct additive in many foods to restrict bacterial growth. The FDA also regulates many antimicrobial treatments, such as irradiation, organic acids, and peroxide.

Types of Antibacterial Cleaning Products:
Antimicrobial (germ-killing) cleaning products used in the home fall into two general categories:

  1. Personal Cleansing Products - Antibacterial soaps or washes that are formulated to kill or inhibit certain bacteria on the hands or body. The FDA regulates antibacterial soaps as over-the-counter drugs.
  2. Antimicrobial Household and Commercial Cleaning Products - These are formulated to kill germs on inanimate surfaces. The U.S. Environmental Protection Agency (EPA) regulates antimicrobial household cleaning products.


Photo of Sir Alexander Fleming
Photo © Copyright The Noble Foundation
Sir Alexander Fleming


In 1928, Sir Alexander Fleming, a scientist, discovered mold growing as a contaminant in a lab dish containing Staphylococcus bacteria. The mold growth oozed a juice that killed the surrounding Staphylococcus cells. From the active ingredient in this mold, penicillin - a widely used antibiotic - was born!

Antibiotic A chemical substance, produced by living microorganisms or made synthetically, which is designed to kill or inhibit the growth of bacteria in the treatment of people and animals infected with pathogens. Antibiotics are not directly used in foods.

Food Safety Implication: In some foodborne illness cases, doctors may prescribe antibiotics to treat patients infected with foodborne pathogens. However, pathogens can mutate and develop antibiotic-resistant strains that antibiotics are not always able to kill. Resistant bacteria also emerge because of overuse and misuse of antibiotics. Once bacteria develop resistance to antibiotic treatment, they can continue to live and/or multiply even in the presence of the antibiotic.

How will the doctor treat my infections if one antibiotic does not work?

Your doctor may try higher doses of antibiotics, a different type of antibiotic, or combinations of antibiotics. In addition, he or she may try to administer the antibiotic in a different way, such as through an injection.

Antibiotic-Resistant Bacteria: Almost immediately after Alexander Fleming's discovery of penicillin in 1928, researchers observed that some bacteria could suddenly withstand this and other "wonder drugs." Today, at least two dozen different kinds of bacteria have developed resistance to one or more antibiotics. Widespread pathogens, such as Staphylococcus, are becoming increasingly resistant to antibiotics.

How Bacteria Resist Antibiotics: There are several ways bacteria can resist antibiotics. Mutation is one way. Sometimes, by chance, bacterial genes mutate during reproduction, subtly altering the genetic nature of the bacterium. Occasionally a mutation may help the bacterium resist a particular drug. While susceptible bacteria die, this surviving microbe continues to reproduce, again and again, until an army of resistant bacteria squares off against the now-ineffective drug.

Microbes also have the ability to share "resistance genes." One way they do this is by conjugation, in which a microorganism carrying a resistance gene meets a susceptible mate, bonds with it, then transfers its genes.

Penicillium Mold
Penicillium Mold
Today, more than 100,000,000 pounds
of penicillin are produced each year!


"At-Risk" Populations (also called highly susceptible populations)
Any group who may be more susceptible to more serious symptoms or side effects from an illness than the general population. At-risk groups for foodborne illness include: very young children, pregnant women, the elderly, and people with weakened immune systems.

Food Safety Implication: Extra care should be taken to assure that at-risk people do not contract foodborne illness.

Why Some People are "At Risk" for Food-borne Illness: Our immune systems help fight diseases, but some people's immune systems may be weakened - or in the case of children, not yet fully developed. As a result, their bodies cannot effectively fight illness.

  • Infants and Children - Their immune systems are not fully developed, and they produce less acid in their stomachs, which makes it easier for harmful microorganisms to get through their digestive system and invade their bodies.
  • Pregnant Women - Pregnancy, by itself, is a period when a woman's immune system is suppressed. The fetus is at risk because harmful microorganisms can cross the placental membranes and infect the developing child, who does not have a fully developed immune system.
  • The Elderly - Poor nutrition, lack of protein in diet, and poor blood circulation may result in a weakened immune system.

  • People with Certain Diseases - The immune systems of people with certain illnesses, such as HIV/AIDS and those on cancer chemotherapy, can be weakened. Thus, their bodies are not able to effectively fight illnesses.