Dehydration

Question 1

Is it possible to decrease water content of a food product to 0%

Answer 1

No

Question 2

When sun drying, the moisture content is reduced to

Answer 2

10-35%

Question 3

Why is sulfur dioxide often listed as an ingredient in dried fruit?

Answer 3

Sulfur protects against enzymatic browning and may cause allergic reactions (headache, coma, death) in some individuals

Question 4

What are the advantages of freeze drying?

Answer 4

• Does not subject the food to high heat
• Does not alter flavour, colour, or structure of the food
• Freeze dried products can be easily reconstituted

Question 5

What is the disadvantage of freeze drying?

Answer 5

Costly

Question 6

All heat transfer is governed by the 1st law of thermodynamics, which states

Answer 6

Energy cannot be created nor destroyed. It can only be converted into other forms of energy

Question 7

Microwave ovens heat foods by converting __________ energy to __________ in water molecules

Answer 7

Radiant; kinetic

Question 8

Industrial heating processes include __________, __________ and __________

Answer 8

Canning, pasteurization and evaporation

Question 9

In the food industry changes in phase of __________ are important, since a large proportion of the mass of most foods consists of __________

Answer 9

Water; water

Question 10

A pressure cooker can cook foods faster because

Answer 10

It can achieve higher temperature

Question 11

The drying efficiency increases when there is sufficient __________ to carry away moisture

Answer 11

Air flow

Question 12

What are the major considerations for all food manufacturers when choosing processing equipment for their plants?

Answer 12

Cost of the equipment, cost of operating, cost of maintaining, available space in the plant, how to clean the equipment, technical support from the manufacturer, types and range of products to be produced

Question 13

Heat processing for __________ time at __________ temperature contributes to better retention of nutritional and sensory qualities

Answer 13

Short; high

Question 14

Application of heat may be detrimental to __________ or __________ attributes in some products

Answer 14

Nutritional or sensory

Question 15

Define wet steam

Answer 15

Any steam less than 100% quality

Question 16

TRUE or FALSE?

Cooling is not the addition of “cold” it is the removal of heat from food

Answer 16

TRUE

Question 17

Define commercial sterilization

Answer 17

There might be a few spores of microorganisms left in the can/food, but they are so damaged that they cannot cause any problem

Question 18

Explain why a fluidized bed drier is advantageous over tunnel drier

Answer 18

It has the porous plate, so air is flown from top and bottom thus drying will be faster

Question 19

Ideally, refrigeration of perishables starts at the time of __________ or slaughter and is maintained throughout transportation, warehousing and storage prior to ultimate use

Answer 19

Harvest

Question 20

TRUE or FALSE?
The principal requirements for effective refrigerated storage are controlled low temperature, air circulation, humidity control and modification of gas atmospheres

Answer 20

TRUE

Question 21

TRUE or FALSE?
Refrigerated storage permits exchange of flavours between many foods. Butter and milk will absorb odours from fish and fruits

Answer 21

TRUE

Question 22

The more salt, sugar, minerals or proteins in a solution the __________ its freezing point

Answer 22

Lower

Question 23

The freezing point of pure water is __________, but actually water does not begin to freeze at __________. Instead, it generally becomes __________ to a temperature several degrees below __________ before some stimulus such as crystal nucleation or agitation initiates the freezing process

Answer 23

0 degrees C, 0 degrees C, supercooled, 0 degrees C

Question 24

TRUE or FALSE?

Repeated freezing and thawing cycles are very detrimental to stored foods

Answer 24

TRUE

Question 25

There are three basic freezing methods in commercial use: Freezing in air (give one example: ____________________); freezing by indirect contact with the refrigerant (give one example: ____________________); freezing by direct immersion in a refrigerating medium (give one example: ____________________).

Answer 25

Air blast freezing; plate freezing; liquid nitrogen

Question 26

Although refrigeration and cool storage reduces the rate of food deterioration, with most foods, it will not prevent deterioration to anywhere the same degree as does __________, dehydration, irradiation, fermentation or freezing.

Answer 26

Heat

Question 27

When refrigerated storage is to be for prolonged periods, various techniques are used to maintain quality, for example: eggs in the shell are sprayed with a thin edible __________ to prevent __________ and __________ loss.

Answer 27

Oil; H2O; CO2

Question 28

TRUE or FALSE?

Low temperature separation and concentration processes employing selective membranes are not applicable in food industry

Answer 28

FALSE

Question 29

The liquid whey is forced through an ultra-filtration membrane to concentrate the __________ above the membrane. The filtrate then can be forced through a reverse osmosis membrane to concentrate __________

Answer 29

Protein; lactose

Question 30

Concentration processes that expose food to 100 °C or higher can cause major organoleptic changes such as cooked flavour and __________ of colour

Answer 30

Darkening

Question 31

Sugar and salt in concentrated solution have __________ osmotic pressure which can draw water from microbial cells or to prevent normal diffusion of water into these cells

Answer 31

High

Question 32

TRUE or FALSE?

Two foods with the same water content can have very different water activity values

Answer 32

TRUE

Question 33

The major factors affecting food deterioration include

Answer 33

Microorganisms, enzymes, insects, parasites, rodents, inappropriate temperature, oxygen, light, physical damage, lengthy storage time