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FOOD POLLUTIONAmal Alghamdi
2013346 BOT
SOME DEFINITIONS• Contamination. The presence of harmful organisms or substances.
– Contaminants can be physical, chemical or biological• Direct Contamination. Contamination of raw foods, plants, or
animals in their natural setting or habitat.• Cross-Contamination. Contamination that is transported from one
source to another.– Cross-contamination can occur during the handling, processing,
preparation, cooking and storage of food.• Foodborne Illness. An illness that occurs from ingesting
contaminated food.• Sanitation. The creation and maintenance of conditions that will
prevent food contamination or foodborne illness
TYPES OF FOOD SAFETY HAZARDS
1. Biological
2. Physical
3. Chemical
4. Allergenic
e.g. Bacteria,Virus, Fungi and prions
Parasite,
e.g. Cleaning fluids,
e.g. Broken glass,
Insecticides, heavy Metals
e.g. Peanut,
screw,
shellfish
stone
BIOLOGICAL HAZARDS – BACTERIA AND FOOD POISONING
• Microscopic• Everywhere!• The main cause of food poisoning
Can’t see ‘em Can’t smell ‘em Can’t taste ‘em
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Direct ContaminationBiological Contaminants
• Bacteria are single-celled
microorganisms and are the leading
cause of food-borne illness
– Putrefactive bacteria (spoil food without
rendering it unsafe; example: digestion
and composting)
– Pathogenic bacteria (dangerous, disease
causing)
Copyright © 2006 Pearson Education Canada Inc., Toronto, Ontario
Biological Contaminants Bacteria Types
• 3 ways pathogenic bacteria can cause illness:
– Intoxication: Botulism, Staphylococcus– Infection: Salmonellosis, Streptococcus, Listeriosis– Toxin-Mediated Infection (combination of the first two)
• Clostridium perfringens (CP)• Escherichia coli 0157.H7 (E. coli)
Pathogenic bacteria must be destroyed or controlled by sanitation methods.
Biological ContaminantsBacteria
Bacteria need certain conditions to grow• Temperature• Time• Moisture• pH• Atmosphere
prevention = controlling these conditions.
Temperature :
Bacteria grow best in temperatures ranging from5°C (41°F) to 60°C (140°F)“The Danger Zone”
Bacteria grow rapidly if potentially hazardous foods are held within these temperatures
Most bacteria are killed between
74°C (165°F) to 100°C (212°F)
Biological ContaminantsBacteria
Copyright © 2006 Pearson Education Canada Inc., Toronto, Ontario
2-9
Biological Contaminants Bacteria
Time: Bacterial duplication
Copyright © 2006 Pearson Education Canada Inc., Toronto, Ontario
Biological Contaminants Bacteria
Time:
Bacterial growth curve
Food can be kept in the temperature “danger zone” for only 2 hours. At this time, the Bacteria is in the “Lag” phase. By 4 hours, the bacteria will be well into the Logarithmic phase
and the food should be considered unsafe to eat.
Moisture:
Bacteria need water to live.
Food:
high water content are most likely to become contaminated.
• Meat
• Cheese
• Salads
• Fruit
Biological Contaminants Bacteria
pH:
Acid/Alkaline content of food is expressed on a scale of 0 to14• A pH of 7.0 is neutral
• Most bacteria prefer a pH of 6.6 to 7.5
• Strong acids and bases will kill
bacteria.
• Bacterial growth is usually halted at a
pH of 4.6 or less
Biological Contaminants Bacteria
PRESERVATION
Salt and Sugar bind to water, making food less likely to be contaminated by bacteria.
Copyright © 2006 Pearson Education Canada Inc., Toronto, Ontario
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Biological Contaminants Bacteria
Atmosphere:• Some bacteria, known as aerobes, thrive in the
presence of oxygen• Others, known as anaerobes, do not require the
presence of oxygen• Others, known as facultative, can adapt and will
survive with or without oxygen• Unfortunately, most pathogenic bacteria are
facultative
• Tiny organisms that depend on nutrients from a living host.– Animals, fish and humans play host to parasites.
• Trichinella. Undercooked game and pork• Anisakis. Raw fish• Tapeworm. Raw beef, pork, fish• Cyclospora. Carried to food by contaminated water.
Biological Contaminants Parasites
Biological Contaminants VIRUSES
• Viruses are the smallest forms of life.– A protein coat with a strand of DNA or RNA
• Viruses need a “host” to multiply, but can survive on food.
• Unlike bacteria, viruses can contaminate ANY food. It is unaffected by PH, oxygen, water content. Viruses can survive freezing
• Transmitted to food via poor hygiene.• Most common: Hepatitis A and Norwalk virus
Biological Contaminants FUNGI
• Simple parasitic life forms that live on dead or decaying organic matter.Mold. Produce toxinsMildewYeast. Usually not harmfulMushrooms. Can be very toxic. Causes liver
failure Chief food sources: beans and grains.
Biological Contaminants PRIONS
• Proteins that maintain nerve cells.• Can “invert” and become infectious• Cooking will NOT destroy prions• Found in ground meats, spinal and brain tissue of
animals that are infected.• Is spread to animals by contaminated feed.• Avoid ground meat, brains, and spinal tissue.
Safe Food Starts with Good Sanitary Habits
What are the sources of food poisoning bacteria in your kitchen?
Consider:Raw Food, pests and pets, people, dirt, dust, rubbish
Intext Figure Pae 661
Wash your hands with warm water and soap before preparing or eating food to reduce the chance of microbial contamination.
To Prevent Foodborne Illness:• Avoid cross-contamination• Thaw meats or poultry in the
refrigerator…• Refrigerate leftovers
promptly…• Keep hot foods hot (140°F or
above). • Keep cold foods cold (40°F or
below).• Mix foods with utensils.• When in doubt, throw it out.
• Do not prepare food if you have a skin infection or infectious disease.
• Discard food from cans that leak or bulge.
• Cook all meat and poultry to 160°F or higher.
• Avoid raw milk or potentially contaminated water or fresh unpasteurized apple cider.
• Wash fruits and vegetables thoroughly before eating.
Recommended Safe Temperatures (Fahrenheit)
Poultry breast, well-done meats
Whole poultry
Medium-done meats, raw eggs, egg dishes,pork, ground meats
Stuffing, ground poultry, reheat leftovers
Hold hot foods
Medium-rare beef steaks, roasts, veal, lamb
DANGER ZONE: Do not keep foods between40˚ F and 140˚ F for more than 2 hours.
Freezer temperatures
180 ˚
170 ˚
165 ˚
160 ˚
145 ˚
140 ˚
40 ˚
0 ˚
Refrigerator temperatures
Bacteria multiplyrapidly at temperaturesbetween 40˚ and 140˚ F.
Figure 19-1(1) Page 662
FARMSWorkers must use safemethods of growing,harvesting, sorting,packing, and storingfood to minimizecontamination hazards.
Food Safety from Farms of Consumers
PROCESSINGProcessors must followFDA guidelines concerningcontamination, cleanliness,and education and trainingof workers and mustmonitor for safety at criticalcontrol points (use HACCP,see text).
TRANSPORTATIONContainers and vehiclestransporting food mustbe clean. Cold foodmust be kept cold at alltimes.
Experiment: Examination of different types of foodMaterials:• N.A. plates• PDA plates.• McConkey Agar plates.• Inoculating needles (loops).• Sterile forceps.• Alcohol swaps (70%).• Different types of food (smoked meat, Rice, Nuts, Peach).• Incubators 37°C sand 28°C.
Experiment: Examination of different types of food
Procedure:1- Under aseptic conditions, transfer a sample of each examined food.2- investigate the type and number of colnies appeared after incubation.
Food Inoculoum Agar Media Temperature (°C) Time (days)
Nuts whole PDA
28 5Rice Whole PDA
Peach Part PDA
Smoked meat loop McConkey Agar
37 1-2Cheese loop NA
Control None NA-McConkey-PDA 37- 28 1-2/5
Thanks for listening
