Presentation on theme: "CHAPTER 3. Objectives How food contamination occurs Why food contamination occurs Identify stages of food preparation where food spoilage occurs Describe."— Presentation transcript:
Objectives How food contamination occurs Why food contamination occurs Identify stages of food preparation where food spoilage occurs Describe and apply safe practices in stages of food preparation
Food Contamination Food poisoning occurs when food is not prepared or cooked safely. Some symptoms of food poisoning are vomiting, diarrhoea and fever. Food can be contaminated by physical means, microbiological modes and enzymatic action.
Physical Temperature of Food Presence of Moisture Presence of Insects Micro- biological BacteriaMoulds Yeasts Enzymatic Like browning of fruits and vegetables
Temperature of Food Temperatures ranging from 4 to 60 degrees Celsius favour bacteria growth. Bacteria is killed at 100 degrees Celsius and inactive at -18 degrees Celsius. Hot food should hence be kept hot and cold food be kept cold so that bacteria is destroyed and bacteria does not grow.
Presence of Moisture Micro-organisms require moisture to grow and would multiply quickly when moisture content is high. People handling food with high moisture content can cross-contaminate micro-organisms from unclean hands. Examples of food with high amounts of moisture are raw meat, seafood, vegetables and fruits.
Presence of Insects Insects and their droppings carry many micro- organisms that are invisible to humans. When they get in contact with food, the area would be contaminated with bacteria and become unhygienic.
Microbiological contamination Microbiological contamination can result in foodborne illnesses. Symptoms include nausea, vomiting, stomach pain, diarrhoea and fever.
Microbiological contamination Bacteria Grows rapidly under moist and warm conditions. Killed when exposed to temperatures over 60 degrees Celsius. Moulds Are fungi that grow on spores Grow well under dark, wet and warm conditions. Usually on bread, cheese and fruits. Yeasts Are fungi that grow by budding. Grow well under moist and warm conditions. Usually on sweet foods like grapes.
Enzymatic Action Enzymes are substances found naturally in animals and plants. Enzymes of humans help break down food into simpler forms. Enzymes of bacteria in raw food help liquefy the food to produce a slimy coating that causes food to spoil faster. However, enzymatic action only affects the appearance of the food.
Food Spoilage Food spoilage can occur anytime such as during food handling, food preparation and food storage. Wrong practices at any stage can introduce micro- organisms into the food.
Stages of Food Spoilage may occur Food Handling Food Preparation Food Storage
Food Handling Wear a hair net Tie up long hair Hair strands Keep fingernails short and clean Dirt in fingernails Wash hands thoroughly with soap and water Bacteria on hands Cough and sneeze into a tissue No dip utensils twice when tasting Germs in saliva
Food Preparation Separate raw from cooked food Use separate chopping utensils Micro-organisms in food Rinse food properly before cooking Dirt and foreign objects on surface Use clean utensils Rinse the utensils thoroughly Micro-organisms on utensils
Food Storage Cover cooked food on the table if it is to be consumed within a few hours. Store food at the correct temperature. Do not store too much food in the refrigerator. Place cooked food above raw food in the refrigerator.
Store food in food containers when keeping them in the refrigerator. Meat that has been defrosted should not be frozen again. Store canned, bottled or dehydrated food away from moist and warm areas.