Food Provenance - Food Processing And Production Flashcards
What is primary processing?
This is changing a basic food to preserve it or prepare it for sale or cooking
What are some examples of primary food processing?
Milling wheat into flour
Heat treating milk
Peeling, stoning and slicing fruit for canning
What is secondary processing?
This is when the primary processed foods are made into other products
What are examples of secondary processing?
Making flour into pasta, bread, biscuits
Making milk into cheese, butter, yoghurt
How are grains of wheat made into flour?
Through the process of milling
How is wheat milled?
First the wheat is cleaned:
Magnets, metal detectors and other machines extract metal objects, stones and other grains such as barley, oats and small seeds from the wheat grain
Then the wheat is conditioned:
Water softens the outer bran layer of the wheat and makes it easier to remove the floury endosperm during milling
Then gristing occurs:
The cleaned and conditioned wheat is blended with other types of wheat to make different kinds of flour. Wheat gluten is sometimes added to increase the protein content of milled flours
Stage 1 of milling:
The grist is passed through a series of fluted break rolls rotating at different speeds. These rolls are set so that they do not crush the wheat but shear it open, separating the white, inner portion from the outer skins.
Stage 2 of milling:
The fragments of wheat grain are separated by a complex arrangement of sieves. White endosperm particles are channeled to a series of sieves of smooth reduction rolls for final milling into white flour
Finally it is separated:
Coarser pieces of bran with endosperm still attached go to a second break roll, and stages 1 and 2 are repeated until the flour bran and wheat germ are completely separated. The result is a number of flour streams containing white flour bran and wheat germ.
Describe whole meal flour:
Extraction rate of 100%, meaning nothing has been removed
It is light brown in colour
Describe brown flour:
Extraction rate of 85-90% (10-15% of the bran is removed)
It is light brown in colour
Describe white flour:
Extraction rate of 75% (the bran, germ, fat and some minerals have been removed)
By law, it must be fortified with iron, calcium, thiamine and niacin
It is white in appearance
What are the different types of flour?
Strong flour
Soft flour
Self raising flour
Gluten free flour
How is strong flour used?
Since it has a higher gluten content, it used for bread making, and in flaky/choux pastry.
The gluten is able to stretch after it is mixed with water and developed
How is soft flour used?
This is used for cake and pastry making and has a lower gluten content
How is self raising flour used?
Similar to other flours but it has a chemical raising agent added to it
How is gluten free flour made?
Made from flours which do not contain gluten e.g. rice, potato flour
It is made for people with coeliac disease
What is homogenisation?
This involves forcing the milk at high pressure through small holes. This breaks up the fat globules in order to spread them evenly throughout the milk
What are the different heat treatments available for milk?
Pasteurised milk
Sterilised milk
UHT milk (ultra heat-treated)
How is milk pasteurised?
It is heated to a temperature of at least 72oC for a minimum of 15 seconds and a maximum of 25 seconds
The milk is then cooled quickly to below 6oC
How is milk sterilised?
It is heated to a temperature of 112-130oC for approximately 10-30 minutes then cooled quickly
How is milk ultra heat-treated?
Heated to a temperature of at least 135oC for 1 second.
It is then put into sterile, sealed containers
What is the effect of pasteurisation?
Kills harmful bacteria
Has little effect on the nutritional value of milk
Extends the shelf life of the milk
What is the effect of sterilisation?
Destroys nearly all the bacteria
Changes the taste and colour
Destroys some vitamins
Unopened bottles can be kept for several months without being in a fridge
What is the effect of ultra heat treatment?
Unopened packs have a long shelf life
Little effect on flavour or nutritional value
What are the different varieties of milk?
Whole milk - 3.5% fat
Semi-skimmed milk - 1.7% fat
Skimmed milk - 0-0.5% fat
Channel island milk - has a visible cream line, higher in calories and fat
Organic milk - comes from cows grazed in fields where no chemicals are used
How is bread made in the industry?
First all the ingredients are delivered to the bakery
Then, all the ingredients are mixed together at high speed for 5 mins. After it is left to prove.
Next, the dough is continuously kneaded for about 2 mins
Then, the tins pass along a conveyer belt where the second proving stage takes place for 50 mins
Then the loaves are baked for 20 mins at 230oC
The baked loaves then come out the oven, they are cooled and then sliced and bagged.
How is flour used to make pasta?
The flour is first mixed with liquid, usually water and sometimes egg
A lumpy dough is formed
It is then put into an extruder where the gluten is developed
It is then forced through different shape dies to make different shapes
It is then dried and packaged
How is butter made?
Butter is made by churning cream to remove the liquid
What are the different types of butter available?
Unsalted butter - nothing extra is added
Salted butter - salt is added for flavour
Clarified butter - butter is melted and the fat that rises to the top is separated and used for cooking
Ghee - a form of clarified butter used in Indian cooking
Spreadable butter - butter with vegetable oil meaning it can be spread straight from the refrigerator
What are the different types of cream?
Half cream - no less than 12% milk fat
Single cream - no less than 18% milk fat
Double cream - no less than 48% milk fat
Whipping cream - no less than 35% milk fat
Whipped cream - no less than 35% milk fat (cream has been whipped)
Clotted cream - no less than 55% milk fat
Sterilised cream - no less than 23% milk fat
What are the steps involved in the making of yoghurt?
Milk is pasteurised
The milk is homogenised
The milk is incubated and the harmless bacteria are added (to change the lactose into lactic acid; the lactic acid causes the milk to coagulate)
The yoghurt is let to set until it reaches the correct acidity level
Fruit or flavourings are then added
What are the steps involved in the making of cheese?
The milk is usually pasteurised and is cooled to 30oC
A starter culture of bacteria is added (so that the lactic acid bacteria change the lactose into lactic acid which helps to coagulate the protein in the milk)
Rennet is added and the mixture is left to set (the enzyme in rennet will coagulate the milk)
The curd is cut so the whey is released
For soft cheese - the whey is left to drain away naturally
For hard cheese - the curds are heated and piled on top of each other to release more whey
The cheese is then milled and for many cheeses, salt is added.
The curd is also pressed into moulds
Finally the cheese is left to ripen
What are the different categories of cheese?
Hard - cheddar, parmesan Semi-hard - Cheshire, Wensleydale Soft ripened or bloomy rind - brie, camembert Blue - blue Stilton Washed rind - stinking bishop Fresh - mozzarella, cottage cheese
What are the advantages of preserving food?
Prevents the action of enzymes Lasts longer Can buy/use products when they are not in season Prevents microorganisms from multiplying Increases the shelf life of foods
What are the disadvantages of preserved foods?
Often contains a lot of fat, sugar and salt
Does not contain a lot of fibre
Some nutrients are lost
Additive may be added to restore the colour
The texture of the food may change
What is canning?
Canning is a form of sterilisation.
Food is packed into cans and then sterilised
Cans are then sealed with a double seam to prevent leakage and to prevent contamination
What are the high temperature methods of perseveration?
Pasteurisation
Sterilisation
UHT
Canning
What are the low temperature methods of perseveration?
Chilling
Blast chilling
Freezing
Accelerated freeze drying
What is the cook-chill process?
Food is cooked to a temperature of at least 70oC
Portioning is carried out
Chilling starts within 30 mins of cooking - rapid chilling where the temperature is reduced to 3oC in 90 mins
Once removed from the chiller, food must be heated immediately to an internal temperature of 70oC.
What are the advantages of cook-chill foods?
No skill required Fresh foods can be kept at maximum quality for a longer time Saves energy in the home Little waste Available in single portions Nutrients are not destroyed
What are the reasons for an increase in frozen food products?
Gives the consumer more choice
Saves time
Useful in emergencies
Extends shelf life
What are the industrial methods of freezing?
Blast freezing
Fluidised bed freezing
Cryogenic freezing
Plate freezing
What are the different methods of drying?
Sunlight Fluidised bed drying AFD - accelerated freeze-drying Roller drying Spray drying Oven-drying
What is sunlight drying?
Drying in direct sun light
Moisture evaporates slowly which may allow the food to become contaminated
What is fluidised bed drying?
Used to clump dry particles into granules which dissolve more easily in water
What is AFD (accelerated freeze drying)?
A combination of freezing and drying
It is quick frozen and then placed in a vacuum under reduced pressure
The heat vaporises the ice which turns to steam and leaves the food dry
Little change to the colour, flavour, texture and nutrition value
What is oven drying?
Warm ovens are used
Suitable for herbs, tea and vegetables
What is spray drying?
Suitable for foods that may be damaged to excessive heating
Liquids are rapidly dried by a hot gas
What is roller drying?
Used for instant breakfast cereal, mashed potato and baby foods
The product is dried on a rotating roller that is heated from inside using steam
What is smoking?
Involves smoking the food over wood. The chemicals in the wood’s smoke give the food flavour and also help to preserve the food.
It is usually dipped in either salt or an acid solution first
How is vinegar used to preserve foods?
Vinegar is an acetic acid with a low pH of 3.5 (bacteria cannot survive below 4.5)
Used for foods such as pickled onions, cabbage and eggs
How is salt used to preserve foods?
Salt is used to coat foods such as ham, bacon and fish
Reduces the moisture content by osmosis
How is sugar used to preserve foods?
Sugar in high concentrations (60% or more) prevents bacteria from growing because it makes the water unavailable
What is MAP/CAP?
MAP/CAP is referred to as modified/controlled atmosphere packaging.
It involves changing the atmosphere around the foods inside the packaging so that growth of microorganisms is slowed down
What are different examples of MAP/CAP?
Packaging fresh foods in peak condition; the colour of the food remains the same until the pack is opened
Replacing the air by ‘gas-flushing’ a combination of gases around the food; gases used are oxygen, nitrogen and carbon dioxide
Sealing the plastic bag or plastic lid to a food tray by means of a double sealing process
How is vacuum packing achieved?
It is done by removing air and sealing the package.
It prevents bacteria from growing.
The food is kept in anaerobic conditions and maintains colour and texture
