3.1.2 Signs of Food Spoilage Flashcards
What are the signs of food spoilage?
mould growing, bruising of fruit, change in colour, loss of water/shrinkage, sprouting in potatoes, change in texture, food curdling, separated
What is natural decay?
when a food is harvested or an animal is slaughtered/collected changes take place inside the food causing it to get spoiled.
What are the main changes of natural decay?
moisture loss and enzyme action
What is moisture loss?
after fruits and vegetables are harvested they continue to respire so water comes out of their leaves and skin. so fruit and veg must be eaten within few days of buying them. other foods like cheese and meat lose moisture if not covered in the fridge
What is the action of enzymes?
enzymes are natural chemicals found in small quantities in living things. most of them are inactive until food is slaughtered/harvested. when activated they break down tissues and food components. causing fruits to ripen by turning starch to sugars. enzymes will break down the food until is decomposes/rots.
When do foods brown/discolour?
when they are cut, bruised, bitten, peeled they discolour
How is browning caused?
enzymic action
plant cells contain vacuoles in the centre carrying a variety of natural substances. outside the vacuole is cytoplasm containing enzymes. when broken open, the enzymes in cytoplasm + oxygen in air mix in with the substances in the vacuole. this is called oxidation and results in colour change/browning
How can you delay enzymic browning?
using acid as it denatures the enzyme protein, cooking the food as heat denatures the enzyme protein, and putting foods into cold water which prevents oxygen mixing with enzymes and substances in plant vacuoles
What is blanching?
plunging prepared food into boiling water for a short time to denature the enzyme protein. then draining them and plunging them in cold water to stop the heat process and preserve colour + flavour. then you can drain and freeze to store.
How do moulds affect foods?
they are small and lots of types exist, it is possible to see them as they grow on surface and have a furry appearance. they contaminate food by growing and multiplying and producing waste products/toxins which spoil taste, appearance, aroma and texture of foods.
What do moulds do?
they multiply and send out tiny spores that land on food and germinate. germinated spores send down roots (mycelium) into food sending many shoots with a fruiting body on each
What do moulds look like?
small blue-green lumps in a softened area with a white appearance like lace
What happens when fruit a ripe?
fruiting bodies will burst and send out a shower of spores that travel through the air to land on other foods.
What happens to food gone moldy in storage?
they will look alright in the inside if mold is cut off the surface but harmful waste product from the mould can cause food poisoning as they spread through the mycelium
How is mould growth prevented?
storing food in a cool dry place, heating the food and storing in acid conditions
