Topic 2: Part B

Question 1

Food processing

Answer 1

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

Question 2

Basic principles of food processing to achieve preservation include

Answer 2

• moisture removal

- heat treatment

Question 3

Moisture removal

Answer 3

removing biological active water in an attempt to stop microorganism growth

Question 4

Heat treatment

Answer 4

pasteurization, blanching, canning, baking, cooking, sterilization

Question 5

Low temp treatment

Answer 5

cold storage

Question 6

Acidity control

Answer 6

controlling pH of the food by adding an acidulate

Question 7

Traditional non thermal processing

Answer 7

through chemical additives or food processing

Question 8

Non thermal processing innovations

Answer 8

irradiation, high pressure

Question 9

Food processing aids

Answer 9

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

Question 10

Food spoils because of

Answer 10

microbiological, chemical, physical or enzyme induced decay

Question 11

Decrease in food losses is achieved mainly by..

Answer 11

food preservation and food additives

Question 12

Food preservation is the use of specific processing techniques to…

Answer 12

reduce spoilage microorganisms in food to improve safety and shelf life

Question 13

Biologically active water in tissues is one of the;;

Answer 13

primary causes of food spoilage.

Question 14

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

Answer 14

• deteriorate quickly,

- can be stored for extended periods

Question 15

Other major causes of spoilage

Answer 15

• 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

Question 16

3 main classes of food preservation

Answer 16

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

Question 17

Chemical food preservation

Answer 17

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.

Question 18

Preservatives

Answer 18

additives that maintain the freshness of a food

Question 19

Biological food preservation

Answer 19

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

Question 20

Salt or vinegar may be added to control…

Answer 20

bacterial growth during fermentation

Question 21

Fermentation

Answer 21

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

Question 22

Physical

Answer 22

• drying
• thermal processing
• cooling
• irradiation

Question 23

Drying

Answer 23

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

Question 24

4 ways of drying

Answer 24

• oven/plate drying
• spray drying
• drum drying
• freeze drying

Question 25

Problems with drying by heat

Answer 25

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

Question 26

Oven/plate drying

Answer 26

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

Question 27

Drum drying

Answer 27

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

Question 28

Spray drying

Answer 28

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)

Question 29

Freeze drying

Answer 29

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

Question 30

3 pretreatments used

Answer 30

• physical
• blanching
• chemical

Question 31

Physical pretreatments

Answer 31

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

Question 32

Blanching pretreatments

Answer 32

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.

Question 33

Chemical pretreatments

Answer 33

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