Food Safety Hazards Micro-organisms that affect food safety

Our Goal To help you understand what micro-organisms are and how they affect food so that you learn how to keep food safe.

Learning Objectives 1.Define a micro-organism; 2.Understand their effects on food and people; 3.Identify different types of micro-organisms; and 4.Understand how they cause illness.

What is a micro-organism? Micro means tiny Organism means living creature Micro-organisms are so small you can’t see them without a microscope.

Effects of Micro-organisms Inert Beneficial Spoilage Pathogens

Types of Micro-organisms Micro-organisms can be grouped as: Bacteria Viruses Parasites Protozoa Fungi – yeasts and moulds Prions

Bacteria They are found all around us. There are typically 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water! Bacteria are the most common cause of foodborne illness.

Bacterial Growth Grow by cell division. Can double in numbers every 10 to 20 minutes After four hours, 20 bacteria can become 1,310,720 bacteria! This video shows e.coli bacteria multiplying.

Effect of Temperature Some bacterial toxins are not destroyed by heat. Cooking bacteria to a high enough temperature for a period of time will kill or inactivate them. Keep bacteria out of the temperature danger zone, to minimize their growth.

Bacterial Toxins Some bacteria excrete toxins. Toxins can make you sick even after the bacteria have died. Symptoms can appear from 1 to 6 hours. Examples include: –Clostridium botulinum –Clostridium perfringens –Staphylococcus aureus –Bacillus cereus Resistant to high heat

Spores A protective ‘shell’. Helps bacteria survive in poor conditions. Some bacteria go dormant (not killed) during cooking. Bacteria resume multiplication once back in the TDZ.

FATTOM Food Acidity Temperature Time Oxygen Moisture

Food Most micro-organisms require food to live. Bacteria like proteins, but can grow on Cooked Vegetables, Rice, Baked Potatoes, Sliced Melons, Sprouts, Garlic & Oil as well. Food you purchase will have bacteria on it when you receive it. That is why food handling is so important to eliminate dangerous germs.

Acidity

Temperature

Time

Oxygen Aerobic - needs oxygen Anaerobic - grows in the absence of oxygen Facultative - can grow with or without oxygen

Moisture High moisture content (‘available water’) helps bacteria growth. Available water (aw) is measured on a scale of 0 to 1.0. Most potentially hazardous foods have 0.86 or higher. Examples include meat, fish, poultry, dairy, fruits and vegetables. Drying foods can lower the risk of bacterial multiplication. Adding water to dried foods supports bacterial growth.

Controlling Growth Some environmental factors help minimize growth. Increased acidity and lowering moisture helps; but The best control is reduced time in the temperature danger zone.

Viruses The smallest of the microorganisms Can resist hot and cold temperatures Often the cause of foodborne illness Don’t multiply in food but can be carried on food People eat the food become infected Examples of viruses commonly transmitted in food: Norovirus (also called Norwalk virus) Rotavirus Hepatitis A & E

Viral Reproduction A virus ( shown in blue ) lands on a human cell and injects its DNA Viruses use the cell’s DNA to make viral DNA The viral DNA makes more viruses Eventually the cell wall bursts sending out viruses to infect other cells Viruses can multiply even faster than bacteria in this manner

Parasites Need a host to survive Very difficult to get rid of once one is in your body Can be single or multi-celled Can come from a number of sources, including: –meat, –seafood, –water, –infected food handlers

Types of Parasites Common parasites in food include: Anisakis from infected fish (see picture) used for sushi and sashimi Trichinella from infected meat usually from wild game and pork Cooking to 70 °C(158 °F) will kill the parasites Freezing to −20 °C (−4 °F) for 7 or more days will kill Anisakis larvae

Protozoa These are single cell organisms Most are too small to see without microscope They are found in water, soil and in food contaminated by food handlers Boiling water will eliminate them Good hygiene including proper hand washing will help prevent infections

Types of Protozoa Common Protozoa: Giardia lamblia (left) is a frequent cause if infection from contaminated water Cryptosporidium also found in water supplies Cyclospora cayetanensis found in contaminated water used to water crops (cases include imported raspberries) Toxoplasma found in cats and dangerous to pregnant women and infants

Fungi This includes moulds and yeasts Often can be seen as fuzzy patches on food Moulds prefer moist environments Can grow at refrigerated temperatures Require oxygen to grow Some produce toxins that can contaminate food Toxins can penetrate foods to a depth of 5 cm or 2 inches (deeper in soft cheeses and liquids) Remove at least 5 cm (2 inches) of food that has mould It is highly recommended to discard food with mould

Mould Growth Food Fruiting body Spores Toxin producing filaments in food

Prions Smaller than viruses Made up only of protein “Mad cow disease” is believed to be caused by prions Creutzfeldt-Jacob disease (CJD) may be a human version of this fatal disease caused by eating beef from infected cattle Special laws in Canada have been put into place to help prevent cattle from becoming infected It is important to purchase beef products from approved (government inspected) suppliers

How Micro-organisms Make Us Sick A ‘foodborne infection’ – happens when food with living bacteria is eaten. A ‘foodborne intoxication’ (sometimes called food poisoning) happens when the food contains toxins produced by bacteria. A ‘toxin-mediated infection’ happens when the food that is eaten has living bacteria on it and these bacteria also produce toxins.

Summary A micro-organism is a tiny living creature Examples include bacteria, viruses, parasites, protozoa, and fungi These organisms can contaminate food making it unsafe to eat If the micro-organisms, or toxins they may produce, are consumed people can become very sick & even die

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