FCE

• 3 types of food spoilage

  microbial, physical, chemical
• definition of food spoilage

  occurs when microorganisms or toxic substances are found in our food
• what is found in microbial spoilage?

  yeast, bacteria and mould
• bacteria are single celled organisms smaller than yeasts and moulds
• they thrive under moist conditions at room temperature around neutral pH
• raw food is easily contaminated by bacteria durving harvesting, storage and preparation
• While most bacteria cause food spoilage, the pathogenic bacteira caude foodborne illnesses
• Bacteria causes the body to experience symptoms such as abdominal pain, vomitting and severe diarrhea
• some common types of pathogenic include salmonella, Eschericha coli and Clostridium perfringes
• Pathogenic bacteria are found mostly in raw food, undercooked food which are cross contaminated
• yeasts are spherical, single celled fungi which are found in the air, soil and skin of fruit
• yeast can also thrive in food with high concentration of low pH (examples: jams, jellies and grapes)
• yeast contamination can appear as slimy patches on the surface of the food (example: ham)
• food with yeasts should not be consumed as allergic reactions or food poisoning can occur
• moulds are multi-celled organisms that grow on surface of food as fuzzy spots of various colors, with white or green being the most common
• moulds require little moisture to survive and grow on relatively fry foods (eg bread or grains)
• moulds can grow in sauces and jams
• most moulds thrive between 25 to 30 °C
• some moulds grow under extreme temp (cold or hot)
• moulds reproduce by producing a large number of spores
• these spores are air borne and heat resistance and will continue any food that come in contact
• growth can still occur in a household refrigerator which is usually set a temperature of 5°C
• some moulds produce poisonous substances such as mycotoxins
• fats turn rancid in the presence of oxygen heat and light
• rancidity breaks down fats into glycerol and fatty acids and produce a distinct off-odour and an unpleasant taste
• foods high in fats are prone to rancidity
• foods that are prove to rancidity include wholegrain nuts, potato chips and prawn crackers
• vegetable oil can go rancid if not stored properly
• physical spoilage occurs when food is physically damaged during harvesting, handling, distribution or storage. This can include flesh bruising, broken skin or damage caused by insects and rodents.
• weevils and other pests can infest opened packages of rice, grain or flour. Pests damage the food by eating grains or the outer skins of plant. Once physically damaged, microorganisms can contaminate food with their waste or body parts, introducing pathogenic bacteria into the food.
• pests can also contaminate food with their waste or body parts, introducing pathogenic bacteria into the food
• effects of environmental factors that affect the rate of food spoilage

  light, oxygen, the pressure of moisture, warm temperature, an acidic environment
• exposure to light sources can result in the breakdown of light sensitive food constituents such as colour pigments, fats, proteins and vitamins such as vitamin C
• exposure to light can also speed up undesirable chemical reactions such as colour pigments, fats, proteins and vitamins such as vitamin c
• presence of oxygen encourages the growth of many microorganisms
• the fats present in food can undergo a chemical reaction (oxidation) in the presence of oxygen, and turn the food rancid
• moisture on the surface of food encourages the growth of bacteria and moulds in food such as fresh meat, seafood, sauces and dips
• high temperature increases the enzymatic reactions in food
• warm temperature speeds up the ripening process and enzymatic browning of fruit and vegetables, oxidation of fats, breakdown of vitamins and loss of moisture
• raw meat stored at room temperature spoils faster than those stored in the chiller