Topic 2: Part B Flashcards Preview

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Flashcards in Topic 2: Part B Deck (33)
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1
Q

Food processing

A

conversion of raw plant and animal tissue into convenient and practical forms for consumption

2
Q

Basic principles of food processing to achieve preservation include

A
  • moisture removal

- heat treatment

3
Q

Moisture removal

A

removing biological active water in an attempt to stop microorganism growth

4
Q

Heat treatment

A

pasteurization, blanching, canning, baking, cooking, sterilization

5
Q

Low temp treatment

A

cold storage

6
Q

Acidity control

A

controlling pH of the food by adding an acidulate

7
Q

Traditional non thermal processing

A

through chemical additives or food processing

8
Q

Non thermal processing innovations

A

irradiation, high pressure

9
Q

Food processing aids

A

specific food additives like gums, natural colouring agents, enzymes and sweeteners

10
Q

Food spoils because of

A

microbiological, chemical, physical or enzyme induced decay

11
Q

Decrease in food losses is achieved mainly by..

A

food preservation and food additives

12
Q

Food preservation is the use of specific processing techniques to…

A

reduce spoilage microorganisms in food to improve safety and shelf life

13
Q

Biologically active water in tissues is one of the;;

A

primary causes of food spoilage.

14
Q

Food with a high aw.. and foods with low aw..

A
  • deteriorate quickly,

- can be stored for extended periods

15
Q

Other major causes of spoilage

A
  • biological changes: growth of microorganisms
  • chemical changes: oxidation or enzyme reactions
  • physical changes: separation of water and oil that can occur in foods like mayo/yougurt as they age
16
Q

3 main classes of food preservation

A
  • chemical: addition of salt, sugar or chemical preservation
  • biological: fermentation
  • physical: drying, heating, cooling, irradiation
17
Q

Chemical food preservation

A

addition of sugar, salt, or chemical preservatives to reduce food spoilage. salt and other preservatives such as potassium sorbet lower the water activity in foods.

18
Q

Preservatives

A

additives that maintain the freshness of a food

19
Q

Biological food preservation

A

fermentation lowers the pH of the food product, resulting in taste changes. encourages growth of friendly bacteria which can inhibit growth of pathogenic bacteria.

20
Q

Salt or vinegar may be added to control…

A

bacterial growth during fermentation

21
Q

Fermentation

A

preservation technique that involves bacteria or yeast acting on the carbohydrates of a food

22
Q

Physical

A
  • drying
  • thermal processing
  • cooling
  • irradiation
23
Q

Drying

A

involved removal of water form the food. the food is preserved because of microorganisms cannot survive in dry habitat. in ancient times drying was done predominantly by sun

24
Q

4 ways of drying

A
  • oven/plate drying
  • spray drying
  • drum drying
  • freeze drying
25
Q

Problems with drying by heat

A
  • loss of heat sensitive nutrients such as vitamin C, riboflavin and niacin
  • can alter sensory properties (colour, texture, etc)
26
Q

Oven/plate drying

A

food spread on slatted floor or on shelves inside kilns or dying rooms. hot air is blown over and through the food. can also be placed on trays that travel through tunnel of hot air. the high temp removes the moisture form the food and often the moisture from the air by creating a vacuum environment

27
Q

Drum drying

A
  1. Food is evaporated
  2. Concentrated product poured over large heated drums that keep rotating and get coated with more and more food product
  3. The thin layer of the food product on the heated drum dries very quickly into thin layers.
  4. These layers are further ground to obtain powders.
    - example is mashed potatoes. NOT good for milk
28
Q

Spray drying

A

spray nozzle sprays tiny droplets of liquid into chamber and the high temp immediately dries these droplets. by the time the droplets get to the bottom of the chamber they are dried and collected. vacuum ensures constant removal of moisture to speed drying process. milk powder dried by this method has better solubility. (coffee, egg whites)

29
Q

Freeze drying

A

food is first frozen then placed in vacuum where ice is evaporated via sublimation. most effective method of drying because food isn’t exposed to high heat (more vitamins intact) but expensive

30
Q

3 pretreatments used

A
  • physical
  • blanching
  • chemical
31
Q

Physical pretreatments

A

some fruits have their skin exposed to lye or hot water to crack skin before drying. shortens drying time and improves texture of end product

32
Q

Blanching pretreatments

A

quick exposure to heat. used for fruits or veggies. pre treatment in freezing or drying. main purpose to inactivate enzymes that affect colour and texture and decrease oxidative degradation of the food.

33
Q

Chemical pretreatments

A

some veggies and fruits are dipped in sulphite solution or exposed to sulphur dioxide gas before drying to prevent growing and to protect against loss of vitamin a and C. can destroy thiamin, may cause allergic reactions