Chapter 9-Food Processing Flashcards
What are the conditions required for micro-organisms?
- food
- warmth
- moisture
- oxygen
- pH
What are the methods for food preservation?
- freezing
- freeze drying: food is frozen then moisture is removed
- drying:moisture is removed
- pasteurisation: milk is heated and cooled rapidly
- canning: can airtight
- jam making: fruit is boiled
- bottling
- preservatives used e.g salt
- irradiation: energy waves are passed through the food to kill micro-organisms
Why is freezing used to preserve foods?
- reduces tempature of food so micro-organisms are inactivated and cannot grow
- changes the water in food to ice, and micro-organisms can’t grow without moisture is the form of water
What is quick freezing?
Quick freezing forms very small ice crystals in food which help to keep the food firm when thawing.
What is slow freezing?
Slow freezing forms large ice crystals in food. When food is thawed, the food becomes soft and nutrienrs are lost.
What is blast freezing?
Blast freezing is carried out commercially at a tempature of -30°C. This is the best method of freezing because the cell walls are not damaged.
What are the three types of freezing?
- quick freezing
- slow freezing
- blast freezing
What are the guidelines for freezing?
- choose good quality fresh food
- chill food before freezing
- use the fast freeze section of the freezer
- open-freeze foods that are likely to stick together
- freeze food in usable quantities
- allow air circulation between the packages in the freezer
- label all packages clearly
What are the guidelines for packaging foods for freezing?
- packaging should be moisture-proof and vapour-proof
- seal bags with wire ties and freezer tape
- remove as much air as possible
- allow headspace to allow liquids to expand
- wrap the sharp shape with foil to prevent tearing the packaging
- label packages carefully
Reasons why food is processed?
- micro-organisms are killed
- it prevents waste
- it prevents enzyme activity
- it adds variety to the diet
- nutritive value is retained
- seasonal food is available all yeae
- food is easier to transport
What foods are unsuitable for freezing?
- vegetables with a high water content
- bananas and avocados; they blacken
- milk, cream amd mayonaise; fat and water seperate
- whole eggs: they crack
What are the two types of freezer packages?
- bags
- rigid containers
Why is good packaging needed?
To prevent freezer burn, which damaged the food
What are the steps to freezing vegetables?
- prepare vegetable as for cooking
- blanch vegetables
- chill vegetables in iced water
- open-freeze vegetables that stick together
- package in freezer bags and remove air
- seal and label
What is the blanching time for peas?
1 min
What is the blanching time for parsnips, turnips, brocoli, french beans and cauliflower?
3 min
What is the blanching time for onions, sprouts and carrots?
4 min
What are the guidelines for freezing fruit?
- freeze as soon as possible after picking
- prepare fruit as for cooking
- open-freeze berry fruits, when frozen, pack in freezer bags or boxes, seal and label
- hard fruits can be frozen in syrup. When packaging, allow headspace for expansion
- label all fruits clearly
Guidelines for breads, cakes and pastries
- freeze either raw or cooked
- pack in freezer bags. Seal and label clearly
- pack decorated cakes upright in polythene boxes
- use breads and scones within one month of freezing
What are the guidelines for freezing meat?
- trim away visible fat
- separate burgers, chops and steaks using waxed paper
- remove as much air as possible before sealing
- label clearly
What are the guidelines for freezing stews and casseroles?
- make in the usual way except that the sauce should be a little thinner
- shorten cooking time by 20 min
- when packaging, allow headspace for expansion
- label clearly
What are the guidelines for buying frozen food?
- the tempature of shop freezer should be -18°
- buy frozen food from a reliable source
- food should be frozen solid
- check the expiry date
- packaging should be properly sealed and not damaged
- food should be stored below the load line in open freezers
What are the guidelines for frozen food?
- follow the instructions for thawing on the label
- thaw food overnight in the refridgerator; thaw the food thoroughly (especially meat and poultry
- only defrost food in a microwave if you intend to cook the food right after it’s thawed
- do not refreeze thawed food unless it cooked thoroughly first
What are the advantages of using a freezer?
- food can be bought in bulk and stored, which saves money
- food is available out of season
- freezing retains colour, flavour and texture of food
- leftovers can be frozen and used later, which saves money
- freezing home-grown produce saves money
Guidelines for buying canned food
- avoid bulging, dented or rusting cans because the contents may cause food poisoning
- read the label to check the contents. Fruit may be canned in syrup or fruit juice. Fish may be canned in oil, brine (salty water) or sauce.
- check the expiry date
Guidelines for buying dry food
- packaging should be intact
- check the expiry date
What happens during the canning process?
Heat destroys micro-organisms and the food in kept in airtight cans to prevent any further contamination by micro-organisms.
What occurs in the drying process?
In the drying process, heat removes the water from the food. This prevents micro-organisms from growing because they can’t live without moisture.
What occurs during irradiation?
During irradiation, energy waves are passed through the food. Micro-organisms are killed. Food keeps for a long time.
What are food additives?
Food additives are substances added to food by the manufacterers in order to improve the food in some way.
What are the functions of additives?
- improve the appearance and flavour of food
- make the food last longer
- reduce the risk of food posioning
- improve the texture of food
- improve the nutritive value
What is an E number?
An E number means that the additive has been tested by experts and has been accepted as safe by the EU.
What are the advantages of additives?
- they make the food last longer and reduce waste
- they allow a wider choice of foods
- the preserve food and so reduce the risk of food posioning
- good-quality food can be consistently provided
What are the disadvantages of additives?
- additives may deceive the consumer
- may cause side effects such aa hyperactivity or skin rash.
- a mixture of additives may be harmful to the body over time
- some people overuse foods containing additives such as MSG and they do not enjoy the taste of fresh foods
What is the purpose of food labelling?
The purpose of food labelling is to inform consumers about food.
What are some advantages of nutrition information?
- helps consumers to follow a healthy diet
- people on special diets can choose or avoid certain foods
- people with allergies can avoid certain foods
What are the two types of date marking?
- best before date
- use by date
What is unit pricing?
This is the price per kilogram or per litre. It is required on foods sold loose, such as fruit, and prepackaged foods sold in varying quantities such as cheese.
What is a convenience food?
A convenience food is a pre-packed which can be prepared quickly and easily.
Why have convience foods become popular?
- many people cannot, or choose not to spend time preparing food
- some people do not have adequate cooking skills
- advertising encourages people to use convience foods
- there is very little waste
- there is a wide variety available
- some children pester their parents to buy fast food
What are the types of convience foods?
- canned and bottled foods e.g soups
- frozen foods e.g pastries
- dried food e.g dried soups
- ready-to-cook foods
- cook-chill foods (already cooked and chilled, need to be reheated
