Food Provenance: Food Processing and Production Flashcards
What is primary processing?
changing a basic food to preserve or prepare it for sale or cooking
What is secondary processing?
using a primary processed food to make another product
What are some examples of primary processing?
- milling wheat into flour
- heat treating milk
- extracting olives from crops
- peeling, stoning, slicing fruit for canning or freezing
What are some examples of secondary processing?
- making flour into pasta, bread, biscuits and other flour-based products
- making milk into cheese, butter or yoghurt
Give the process of roller milling
1) magnets extract metal objects, stones and other grains
2) throughout the cleaning process, air currents life off dust and chaff
3) water softens the outer pericarp layer of the wheat and makes it easier to remove the floury endosperm
4) cleaned and conditioned wheat is blended with other types of wheat in gristing, makes different kinds of flour.
5) wheat gluten sometimes added to increase protein content
STAGE 1: grist is passed through fluted break rolls rotating at different speeds, they do not crush the wheat but shear it open
STAGE 2: fragments of the wheat grain are separated by a complex arrangement of sieves, endosperm particles are channelled to a series of sieves of smooth reduction
8) coarser pieces of bran with endosperm are passed through second rollers, and stage 1 and 2 are repeated until complete separation
What is extraction rate?
how much of the whole grain is used
What are the uses of strong flour?
higher gluten content, needed in bread making, able to stretch
What are the uses of soft flour?
cake and pastry making, lower gluten content
What are the uses of self raising flour?
chemical raising agent
What are the uses gluten-free flour?
for coeliacs
What is coeliacs disease?
a medical condition caused by an allergy to the protein gluten, present in cereal
What is fortification?
when a nutrient is added to a product to improve its nutritional value
What is an emulsion?
a mixture of two liquids
What is homogenisation?
involves forcing the milk at high pressures through small holes, breaking up the fat globules in order to spread them evenly throughout the milk and preventing separation of the cream layer
What is pasteurisation?
a method of heat treating milk to kill harmful bacteria
What is sterilisation?
a method of heat treatment which kills all microorganisms
How do carry out pasteurisation?
Heated to a temperature of at least 72ºC for a min of 15s and max of 25s
Milk quickly cooled to below 6ºC
What is the effect of pasteurisation?
Kills pathogenic bacteria
Little effect on nutritional value
Extends the shelf life of the milk
How do we carry out sterilisation?
Heated to a temperature of 113-130ºC for approximately 10-30 mins
Then cooled quickly
What is the effect of sterilization?
Destroy nearly all bacteria
Change taste and flavour
Destroy some vitamins
Unopened bottles can be kept for many months not in fridge
How do we carry out UHT?
Heated to a temperature of at least 135ºC for 1 second
Put into sterile, sealed containers
What is the effect of UHT?
Unopened packs have long shelf life
Little effect on flavour or nutritional value
What are the feature of whole milk?
- nothing added or removed
- min 3.5% fat
What are the feature of semi-skimmed milk?
- most popular milk in the UK
- 1.7% fat
What are the feature of skimmed milk?
- 0-0.5% fat
- slightly more calcium than whole milk
- lower levels of fat soluble vitamins
- not recommended to children under 5
What are the feature of channel island milk?
- high calories and fat than whole milk
- higher content of fat-soluble vitamins
What are the feature of organic milk?
- no added chemical or fertilizers, cows graze in fields
- treated the same as normal milk
What are the main ingredients of bread?
flour - strong so high gluten
yeast - to rise
salt - added to taste
vegetable fat - make the loaf lighter and airier, extend shelf life
water
What is the first stage of the bread making process?
- ingredients mixed together at high speed
- dough removed and divided into pieces
- left to prove
What is the second stage of the bread making process?
- kneaded continuously for 2 mins
- dropped into greased baking tins
What is the third stage of the bread making process?
second proving for 50 mins
What is the forth stage of the bread making process?
bread passed into an oven for 20 mins
What is the fifth stage of the bread making process?
cooling for 90 mins and taken out of tins
How do you make flour into pasta?
1) flour mixed with liquid (water/egg)
2) lumpy dough
3) extruder where dough is developed
4) different shapes when cut after being rolled out
5) dried for several hours
How is butter made from milk?
churning cream to remove even more liquid
How is cream made from milk?
rotated at high speeds until cream separate
then pasteurised to remove harmful bacteria and enzymes that affect flavour
How is yoghurt made from milk?
1) milk pasteurisation
2) homogenised
3) milk incubated and harmless bacteria added
4) yoghurt left to set until correct acidity
5) fruit and flavour added
Why is milk homogenised?
to distrubte the fat particles evenly throughout the milk
Why is milk incubated and given harmless bacteria?
to change the natural sugar (lactose) into lactic acid, which causes milk to coagulate and thicken
How is cheese made from milk?
1) pasteurisation then cooled to 30ºC
2) starter culture bacteria added
3) rennet added and mixture left to set
4) curd is cut so whey is released
5a) soft cheese - whey drained away naturally
5b) hard cheese - curd piled up to release more whey
6) cheese milled and pressed into moulds
7) left to ripen
What are the advantages of preserving food?
- prevents action of enzymes
- lasts longer, less frequent shopping
- buy when not in season
- prevent microorganisms from multiplying
- increase range of foods available, give more variety in diet
- increase shelf life
- save time, effort, fuel
What are the disadvantages of preserving food
- lots of fat, sugar or salt
- does not contain a lot of fibre
- nutrients are lost
- sometimes more expensive than fresh
- texture can change
What is canning?
A form of sterilisation, packed into aseptic cans
To prevent leakage or contamination
What are the disadvantages of canning?
- texture may change
- loss of nutrients
What is blast chilling?
Cooled as quickly as possible
Below 3ºC in 90 mins
What is cook-chilling?
1) food is cooked with centre at least 70 ºC
2) portioning under hygienic conditions
3) chilling within 30 mins of cooking, 3ºC in 90 mins
4) food reheated immediately once removed
What are the advantages of cook chilling?
- no skill required
- fresh food kept max quality
- little waste
- nutrients not destroyed
What is cook-freezing?
blast-frozen and stored at -20ºC
What is dehydrating?
Removing water so microorganisms cannot grow
How is vinegar used as a preservative?
used for foods such as pickled onions, cabbage and eggs
How is salt used as a preservative?
coat meat and fish to reduce water lost by osmosis
How is sugar used as a preservative?
high concentrations prevent bacteria growth because water is unavailable
jams, marmalades and jellies
What is modified atmosphere packaging?
- packaging food at peak conditions
- gas-flushing a combination of gases around the food
- sealing the plastic bag or plastic lid airtight (hermetic)
What is vacuum packaging?
- removing air and sealing the packaging
- kept in anaerobic conditions
- does not lose taste or flavour
