Food processing and production Flashcards

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1
Q

What is primary processing?

A
  • Prepares raw food to be eaten, cooked immediately or used as an ingredient
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2
Q

How is wheat processed to produce flour?

A
  • A wheat grain is made of bran (mostly fibre), endosperm (mostly starch) and germ (vitamins, protein and fat)
  • Wheat grains are harvested and then cleaned to removes any stones or dust
  • Water softens the outer layer (bran) of the grain
  • It’s blended with other types of wheat in a process called gristing
  • The grist is passed through fluted break rolls rotating at different speeds so the wheat is sheared open
  • The fragments of the wheat are separated by sieves
  • The endosperm go through reduction rolls for final milling
  • Coarser pieces of bran are passed through the rolls again
  • In the end, wheat is separated into flour, germ and bran
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3
Q

What are 3 different types of flour, their components and extraction rates?

A
  • Wholemeal flour contains all of the parts of wheat grains, and so has an extraction rate of 100%
  • Brown flour does not contain the bran, so it had an extraction rate of 85-90%
  • White flour has an extraction rate of 70-75% as it doesn’t contain the germ or the bran
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4
Q

What is milk like, and what is done to it as a result?

A
  • Milk is an emulsion of oil in water, so the fat rises to the top and creates a cream line
  • Homogenisation is the process of forcing milk at high pressure through small holes, which breaks up fat globules
  • This spreads them out evenly in the milk
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5
Q

Why is milk heat-treated, and list 3 ways this is done.

A
  • To destroy pathogenic bacteria
  • Pasteurised: heated to at least 72°C for 15 seconds, then cooled below 6°C
  • Sterilised: heated at 110°C for 10-30 minutes, then cooled
  • Ultra heat treatment (UHT): heated to 135°C for 1 second and put into sterile, sealed containers
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6
Q

List 2 issues with heat-treated milk.

A
  • All of the bacteria in sterilised milk is killed, so it tastes different and many group B and C vitamins are lost
  • UHT milk has slightly less nutritional value and a different taste to pasteurised milk
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7
Q

How are fruits and vegetables processed to become a food product?

A
  • Fruits and vegetables are washed with water to remove dirt, insects and chemical sprays
  • They’re sorted into different sizes and shapes
  • Pits are removed
  • They’re squeezed for juice/ dried/ crushed or pressed to extract oils
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8
Q

How is meat processed?

A
  • Some (like beef) are hung and dried to make them more tender and improve their flavour
  • The feathers and internal organs of poultry are removed
  • The wings and legs of poultry are tied so it cooks evenly
  • Meat is chopped, sliced or cut
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9
Q

How is cream made?

A
  • The fat in milk rises to the top as it is less dense, and can be ‘skimmed off’ (to aid the separation, milk is rotated at a fast speed)
  • The cream is then pasteurised to kill pathogenic bacteria and enzymes that affect its taste and would shorten its shelf life
  • Different types of cream have different amounts of milk fat (single cream has 18%, and double cream has 48%)
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10
Q

How is butter made?

A
  • Cream is churned to remove more liquid
  • This agitates the cream until the fat droplets stick together
  • The cream gets thicker until it forms a solid mass of butter
  • Butter has a fat content of between 80 and 90%
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11
Q

How is cheese made?

A
  • The milk is pasteurised to kill pathogenic bacteria
  • Bacteria is added to turn lactose into lactic acid to help coagulate the protein in milk, preserve the cheese and to develop a sour flavour
  • Rennet is added and the mixture sets into solid cheese curds
  • The whey (remaining liquid) is removed
  • In soft cheese it is allowed to drain away naturally, but in hard cheeses the curds are heated and piled on top of each other to remove more whey
  • The cheese is milled, salt added for certain types, and pressed into moulds
  • It is left to mature
  • Bacteria or mould may be added to change the flavour
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12
Q

How is yoghurt made?

A
  • The milk is pasteurised and homogenised
  • Bacteria are added that that change lactose to lactic acid, which causes it to coagulate (thicken) and gives it a sour taste
  • The yoghurt is left until it reaches the correct level of acidity
  • Fruit and flavourings are added
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13
Q

How is pasta made from flour?

A
  • It is mixed with eggs or water
  • The dough is shaped by forcing it thorugh a metal die, and it is then folded or twisted
  • Colourings may be added
  • Pasta is then sold either fresh or dried
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14
Q

How is bread made from flour?

A
  • Flour is mixed with water and yeast to make a dough
  • The dough is kneaded to develop the gluten
  • The dough is proved to let the yeast ferment
  • The dough is baked in the oven
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15
Q

How are foods canned?

A

It’s a from of sterilisation.
- Food is either packed into a can and then sterilised
- Or it can be sterilised and placed in aseptic cans
- They’re then sealed to prevent leakage and contamination

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16
Q

What are 2 disadvantages of caning foods?

A
  • Their texture might change
  • Canned foods lose B group vitamins and vitamin C
17
Q

List 5 low temperature methods of preserving food. Why do they work?

A

They slow down the speed that bacteria reproduce at, and freezing food makes bacteria dormant.
- Chilling
- Freezing
- Cook-freeze
- Blast chilling
- Accelerated freeze- drying (AFD)

18
Q

How are foods chilled?

A
  • They’re cooled to between 0 and 5°C
19
Q

How are foods frozen?

A
  • They’re cooled to -18°C
20
Q

What does it mean to cook-freeze a food?

A
  • The food is cooked, then rapidly frozen
21
Q

What is blast chilling?

A
  • Blast-chillers rapidly cool cooked food to below 5°C within 90 minutes
22
Q

What is accelerated freeze-drying (AFD)?

A
  • Food is rapidly frozen and dehydrated to remove moisture
  • Adding water to the food restores the food to its original texture and taste
23
Q

Describe drying foods.

A

It works as microorganisms need moisture, so without it they cannot grow.
- Hot or warm temperatures are used to remove the moisture
- Dried foods need to be stored in a cool, dry place
- Their colour, taste, texture and nutritional value can be affected

24
Q

What impact does smoking foods have?

A
  • The food is dipped in salt or an acid solution first
  • Chemicals in the wood being burnt give it flavour and help preserve it
25
Q

How do acids, salt and sugar preserve food?

A
  • They either kill bacteria or stop them from reproducing
  • Bacteria cannot survive beneath a pH of 4.5 (vinegar’s pH is 3.5)
  • Salt reduces moisture by osmosis
  • In high enough concentrations (over 60% of the product) sugar makes water unavailable, so bacteria cannot grow
26
Q

What is monitored/ controlled atmosphere packaging (MAP/ CAP)?

A
  • It slows down the growth of microorganisms as they use oxygen for growth, which increases the shelf life
  • Fresh foods are packaged
  • The air around it is replaced through ‘gas flushing’ (different proportions of oxygen, nitrogen and carbon dioxide according to the food)
  • Sealed with a plastic bag or lid to make the container airtight
  • As a result once the container is opened, the food has a regular shelf life
  • It is used for chilled meat, fruits and vegetables
27
Q

What is vacuum packing?

A
  • Air is removed from the package and it is sealed
  • The food is kept in anaerobic conditions, which prevents bacteria from growing
  • Once opened it has a regular shelf life
  • The food maintains its colour and texture