Forms of Contamination that Cause Foodborne Illness Unit 3: Food Safety Infection or intoxication caused by the transfer of microbial or chemical contaminants from food or water to humans. Biological • Most foodborne illnesses are caused by pathogens, a form of biological contaminant. Chemical • Foodborne illness is also contributed to consuming beverages or food contaminated with foodservice chemicals. Physical • Food can also be contaminated when objects get into the food. Even when natural objects are left in food like bones. Microorganisms are small living organisms like bacteria that can only be seen through a microscope. Harmful microorganisms are called pathogens. Some pathogens make you sick when you eat them, others produce poisons or toxin within your body. The four types of pathogens: • Bacteria • Viruses • Parasites • Fungi • • • • Bacteria can be found anywhere and they live in our bodies. Some types of bacteria keep us healthy and other make us sick. Bacteria cannot be seen, smelt or tasted. If conditions are correct, bacteria will grown in rapid numbers. The most important way to prevent bacteria from causing a foodborne illness is to control time and temperature. Bacteria need six conditions to grow that we refer to as FAT TOM. F—Food • The nutrients in food promoted the growth of microorganisms. Foods that contain moisture and are protein-rich are most susceptible. For example: meat, milk, eggs and fish. A—Acidity • • • Bacteria grow in foods that have little to no acid. pH is used to test the acidity of foods. The pH scale ranges from 0 – 14.0. A value of 0 is highly acidic, while a value of 14 is highly alkaline or basic. A pH of 7 is neutral. Bacteria grows best in food that is neutral or slightly basic. T—Temperature • • • • Bacteria can grow rapidly between 41°F and 135°F (5°C to 57°C). This is referred to as the temperature danger zone (TDZ). Bacteria grow even more rapidly from 70°F to 125°F (21°C to 52°C). Bacteria growth is limited when food is held above or below the temperature danger zone. T—Time • Bacteria need time to grow. The more time spend in the temperature danger zone [41°F and 135°F (5°C to 57°C)], the more opportunity bacteria have to grow to unsafe levels. O—Oxygen • Number of Cells Time in TDZ 1 cell 0 min. 2 cells 20 min. 4 cells 40 min. 8 cells 1 hr. 16 cells 1 hr. 20 min. > 1 billion cells 10 hrs. Some bacteria need oxygen to grow, others grow when there is no oxygen. M—Moisture • • Bacteria grow well in foods with high levels of moisture. The amount of moisture in a food is known as the water activity (aw). The aw scale ranges from 0.0 to 1.0. The higher the value, the more available moisture in the food. For example, water has a water activity of 1.0. Viruses are carried by humans and animals. They require a living host to grow. • Viruses do not grow in food but they can still be transferred through food and infectious to the food. • People can get viruses from food, water, or any contaminated surface. Foodborne illness from viruses usually occur through fecal-oral routes. Norovirus is one of the leading causes of foodborne illness and is often transmitted through airborne vomit particles. • Viruses are not destroyed through normal cooking. This is why personal hygiene is so important when handling food and food-contact surfaces. • • • • • Parasites require a host to live and reproduce. Parasites are commonly found in seafood, wild game, and food processed in contaminated water, such as produce. One way to prevent foodborne illnesses from parasites is to purchase food from reputable suppliers. Cooking food to the required minimum internal temperatures is also important. • • • • Fungi includes yeasts, molds, and mushrooms. Some molds and mushrooms produce toxins that cause foodborne illness. Throw out all moldy food, unless mold is a natural part of the food. Harmful mushrooms are difficult to recognize, purchase all mushrooms from approved, reputable suppliers. Chemicals (cleaners, polishes, machine lubricants, sanitizers, and/or pesticides) can contaminate food if they are used or stored the wrong way. The best way to prevent chemical contamination is to store chemicals away from prep areas, food-storage areas, and service areas. Some common objects that can get in food are shavings from metal cans, wood, fingernails, staples, bandages, glass, jewelry and dirt. Mild to fatal injuries are possible. Purchase food from approved, reputable suppliers to prevent physical contamination.