In this lesson, we will learn about the different types of food contamination. We’ll go over and learn more about the three main categories: physical, chemical, and biological.

The Types of Food Contamination

There are some food contaminants that you can see, such as plastic or mold; while others you cannot, such as antibiotics and salmonella. No matter what the food contaminant is, as a consumer, we don’t want food contamination.

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There are three categories of food contamination: physical, chemical, and biological. Some of these contaminants are safety concerns, while others are quality concerns. All food contaminants can get into food through malicious intent, but here we will discuss other ways that food contaminants can become a part of the product.

Physical Contaminants

Physical contaminants are any physical objects in food that are not meant to be in the food. This can include hair, glass, and insects. Some physical contaminants, such as hair, are not considered food safety concerns. While others, such as glass, are considered food safety concerns.

Physical contaminants often enter the product through not following good manufacturing practices (GMPs). GMPs include wearing proper protective equipment, such as hair nets. It also includes keeping a clean facility with equipment that is in good shape. For example, most facilities have policies that completely ban glass so as to prevent it from contaminating the product.

Since most equipment is metal, it is difficult to ensure that no metal bits will enter the product. So many facilities will have metal detectors that will alert personnel if any metal is found in the product. If metal is detected, then the source of the metal is determined and fixed in order to prevent further metal from contaminating the product.

It’s creepy to find an insect in your food. In our culture, we frequently connect finding insects in our food with the processing conditions being unsanitary. Food processors try to prevent insects in food but some products are almost impossible to ensure no insects. A head of lettuce, which grows in the open for many insects to infest, can’t be cleaned on the inside without destroying it. Since most insects aren’t a safety concern, a few insects are legally allowed inside the final products. So insects as a physical contaminant are typically considered a quality concern instead of a safety concern.

Chemical Contaminants

Chemical contaminants are any chemicals in food that are not meant to be in the food product. These include antibiotics, pesticides, and cleaning agents. Many of these contaminants are food safety concerns, although it’s possible for them to be quality concerns, such as a blue dye accidentally being added to the orange gelatin.

Many chemicals, such as antibiotics or pesticides, are used in agricultural production of food. Yet these are often not safe for human consumption. So food companies must ensure that there are no chemical residues in the product. For example, cows may be fed antibiotics to kill a disease the cow has. Yet this antibiotic can end up in the cow’s milk. If we were to drink that milk, we would end up drinking the antibiotic as well. So the milk is tested for antibiotics to ensure that there are no antibiotic residues.

Cleaning agents are necessary to clean up possible physical contaminants and destroy biological contaminants. Yet cleaning agents can be harmful if ingested in high enough quantities. For this reason, cleaning must be well controlled to ensure that no cleaning agents can end up in the final product.

Allergens are also considered a chemical contaminant, although they fall under slightly different rules. Typically the allergen present is meant to be in the product, so it’s only considered a contaminant if the allergen is not declared on the food label.

Biological Contaminants

Biological contaminants are any unwanted microbes in food. There are some wanted microbes in food, so these are not contaminants; for example, yeast in bread or specific bacteria cultures in cheese. Yet there are many unwanted microbes. We often hear about the microbes of safety concern, such as listeria, salmonella, and e-coli, but there are also many microbes that are not of safety concern but are a quality concern, such as lactobacillus.

Many of these microbes are found naturally in food. So the job of food processors is to destroy the microbes that are there and/or prevent further growth.

The canning process is specifically designed to destroy microbes and prevent their growth. Canned products are in an anaerobic condition; there is no oxygen present. Most microbes need oxygen to grow, so this prevents the growth of microbes. But there is one microbe, Clostridium botulinum, which only grows in anaerobic conditions. So the processing temperature of canning is specifically set to destroy the clostridium botulinum.

Most food processors don’t worry about microbes of quality concern. In order to destroy all of the microbes, the food itself would need to be destroyed as well. Instead, they set a ‘best by date.’ Most of the quality microbes left in the food are fairly slow growing, and as long as the product is used before the ‘best by date,’ the quality microbes will not have a chance to grow and reduce the quality of the product.

The effects of some biological contaminants can be seen, such as mold on bread, but the biological contaminants themselves often can’t always be seen.

Lesson Summary

There are three main categories of food contaminants: physical, chemical, and biological. Each category can have food contaminants that are of safety concern or of quality concern.

Physical contaminants are any physical objects in food that are not meant to be in the food and include hair, metal, glass, and insects. Metal and glass can be considered safety concerns while the food is being consumed, since these can cut the mouth or throat of the consumer, while hair and insects are typically considered quality concerns.

Chemical contaminants are any chemicals in food that are not meant to be in the food product and include antibiotics, cleaning agents, dyes, and pesticides. Antibiotics, cleaning agents, and pesticides are typically considered safety concerns. While products such as dyes are typically considered quality concerns.

Biological contaminants are any unwanted microbes in food and include spoilage and pathogenic microbes. Spoilage microbes, such as lactobacillus, are quality concerns. While pathogenic microbes, such as listeria, are safety concerns. Some microbes are not considered contaminants, such as yeast in bread, because these are meant to be in the product.