Flashcards in C1a Deck (9):
What are additives and what are some?
-substances added to foods improve flavour, colour or prolong expiry
*food colours make food look more appetising
*flavour enhancers bring out the taste and smell of food without adding their own taste
*antioxidants help to preserve food
*emulsifiers help oil and water blend together in foods
What is the structure of an emulsifier?
-hydrophobic (likes oil) tail
-hydrophilic (likes water) head
What is an emulsion?
-a mixture of oil and water
-made up of lots of droplets of one liquid suspended in another liquid
How do emulsifiers work?
-stops oils and water separating
-when you shake a oil and water together the oil with an emulsifier the oil forms droplets, bonded to a coating of emulsifier
-the hydrophobic end is bonded to the oil, and the hydrophilic end is facing onward
-other oil droplets are repelled by the hydrophylic head, while water latches on
-the emulsion won't separate
Why are many foods cooked?
-better texture and taste
-easier to digest cooked
-high temperature kills microbes that cause diseases
-some foods are poisonous raw, e.g. kidney beans
How are eggs and meat changed in cooking?
-egg and meat are proteins
-energy from cooking breaks some chemical bonds in the protein and allows its molecules to change shape
-this is denaturing
-a chemical change and irreversible
-giving food a more edible texture
How are potatoes changes during cooking?
-potato cells have rigid cell walls made of cellulose
-human's cannot digest cellulose
-cooking potatoes ruptures the cell walls and the starch grains inside the cell swell up and spread out
-making the potato softer, more flexible and easier to digest
What happens when baking powder is is heated?
-sodium hydrogencarbonate--->sodium carbonate+carbon dioxide+water