food safety Flashcards
in what conditions do microorganisms grow?
1.warm temperature
2.plenty of moisture
3.plenty of food
4.the right pH
5.enough time (bacteria split every 10-20 minutes)
how can you slow or stop growth of microorgansims?
change any one of the optimum conditions
what is a microorgansim?
bacteria, mould, yeast, most harmless but some pathogenic and spoil food and give food poisoning
how can you change conditions that bacteria grow in?
use fridge to change temp, pickle the food to change pH, add salt to absorb moisture and dry out food
what is a high risk food?
ready-to-eat foods that, if not stored correctly, could grow harmful bacteria, they are moist and high in protein(food)
what are examples of high risk foods?
cooked meat, fish and poultry
dairy products
gravies, stocks and sauces
shellfish
cooked rice
is raw chicken a high risk food?
no only once cooked as you dont eat it raw
how do you know meat is fresh?
brightly coloured, firm, fresh smell
how do you know fish is fresh?
shiny skin, red glls, clear eyes, clean/salty smell
what is an enzyme?
a special protein that acts as a biological catalyst
what is ripening?
.enzymes in fruit cause them to ripen, which affects the sweetness, colour and texture of the fruit
.e.g. unripe bananas are green and firm - enzymes break down starch inside them making banana softer & sweeter
what is browning?
.when you slice fruits (apples, pears etc.), the oxygen in the air will turn the fruit brown, enzymes inside the fruit speed up this process.
.leaving some fruit (bananas, avocados etc) to overripen will give them a brown colour too
how do you control enzyme activity?
add an acid-if you dip fruits into lemon juice the acidic conditions stop enzymic browning (enzymes work best at specific pH)
blanching-(plunging into boiling water for short time period) used to prepare veg for freezing, natural ripening enzymes cause veg to lose colour, texture, flavour and nutrients over time. freezing slows enzymes
how do moulds spoil foods?
change looks, smell and taste of food, ‘fuzzy’ appearance, even if scraped off toxins may still remain and cause food poisoning
how do yeasts spoil foods?
ferment fruits by fermenting sugars and turning into alcohol or carbon dioxide
what is the danger zone?
5-63 degrees c
optimum temp is 37 degrees c for bacterial growth
what temperature should you chill foods at?
0-5 degrees c
slows bacterial growth and extends shelf life