Food preservation

Question 1

Principle of food preservation
Prevention or delay of microbial decomposition (4 by)

Answer 1

By keeping out microorganism (asepsis)
By removal of microorganism (filtration)
By inhibiting the growth and activity of microorganism (drying, anaerobic condition, lowering the temperature, etc.)
By killing the microorganism (heat genial radiation)

Question 2

Prevention or delay of self-decomposition of the food (2 by)

Answer 2

By destruction or inactivation of enzymes
By prevention or delay of purely chemical reactions o e.g. prevention of oxidation

Question 3

Prevention of damage

Answer 3

prevant damage caused by insects animals mechanical

Question 4

Asepsis 1

Answer 4

Outer layer of animal and plant tissue protects the inner layer from microorganisms.
This protective covering will delay / prevent microbial decomposition o e.g. shells of nuts, skins of fruits and vegetables etc.

Question 5

Asepsis 2 - packaging of food

Answer 5

Wrapping, hermetically sealed containers (airtight).
This methods will prevents primary contamination during handling

Question 6

Asepsis 3 - sanitary method

Answer 6

handling and processing foods
e.g. in the dairy industry, contamination with microorganisms is avoided as much as possible in the production and handling of milk.

Question 7

Removal of microorganism 1 - filtration

Answer 7

Complete removal by using a pre-sterilized filters e.g. in fruit juices, soft drinks and water.
Coarse filters are initially used to remove the large compounds and this is followed by ultrafiltration

Question 8

Removal of microorganism 2- centrifugation

Answer 8

Particle separation through centrifugation force,
Through differences in size, shape and density
Three groups, namely separation of immiscible liquids, clarification of liquids by removal of small amounts of solids, and removal of solids

Question 9

Removal of microorganism 3 -washing

Answer 9

Helpful in removing soil microorganisms from fresh fruits and vegetables that may be resistant to heat process during canning

Question 10

Removal of microorganism 4 trimming

Answer 10

trim away spoiled portions of food

Question 11

Anaerobic condition

Answer 11

achieved by a complete fill, evacuation of the unfilled space, replacement of air by C02 or N2 and others.

Question 12

high temp 1- pasteurization importance

Answer 12

Heat treatment will not harm the quality of product
Main spoilage microbes are not very heat resistant e.g. yeast in fruit juices
Kill pathogens
Any surviving organisms will be treated with other preservative methods
Competing organisms are to be killed, allowing a desired fermentation

Question 13

high temp 1- pasteurization supplementation

Answer 13

Refrigeration.
Keeping out microorganisms by packaging.
Maintenance of anaerobic conditions.
Addition of high concentration of sugar.
Presence of chemical preservatives (e.g. sodium benzoate)

Question 14

high temp 2- heating at about 100

Answer 14

Sufficient to kill all microbes but not spores,
Many acid foods are successfully preserved at 100°C.igh

Question 15

high temp 2 -ways to heating to 100

Answer 15

Boiled, Immersion, Baking, Simmering, Roasting, Frying, Blanching, Exposure to flowing steam

Question 16

high temp 3 -sterilization

Answer 16

Sufficient to kill all microbe and spores
All commercially sterile foods should be stored in cool and dry place to prevent any survival thermophilic spores from germinating and cause, spoilage to the foods.
In general, microbial spoilage can occUr due to under processing © gentand/or leakage after processing

Question 17

objective of heating food 6

Answer 17

To destroy pathogens and spoilage microorganisms
To destroy the vegetative cells and spores of yeast, bacteria and moulds
To destroy undesirable enzymes this can affect the quality of foods.
To control the growth of suRviving microorganisms
To retain the acceptance and nutritional quality of foods
To reduce competition

Question 18

low temp 1- chilling

Answer 18

Temperature of 6°C can prevent the growth of pathogens except Clostridium botulinum type E and retard the growth of spoilage microorganisms.

Question 19

low temp 2 -freezing

Answer 19

Cause reduction in number of viable microorganism but does not sterilize the food.
The percentage of microorganisms killed during freezing and storage varies depending on:
Substrate (kind of food)
Type of freezing

Question 20

advantage of fast freezing

Answer 20

Smaller ice crystal form - less mechanical destruction to food
Short period of solidification - sudden death to microorganisms and quick inactivation of the enzymes.
Food quality after thawing is better

Question 21

drying

Answer 21

lower the water content of food to a point where the activities of enzymes and food spoilage and food poisoning microorganisms are destroyed / inhibited.

Question 22

Microorganisms need water for

Answer 22

transport of nutrients, nutrient metabolism, and removal of cellular wastes

Question 23

chemical preservative

Answer 23

A substance or a mixture of substance which are specifically added to prevent deterioration or decomposition of a food”

Question 24

Chemical preservatives are used mainly to inhibit the growth and activity of microorganisms by:

Answer 24

(a) Interfering with their cell membranes
(b) Their enzyme activity
(c) Their genetic mechanisms

Question 25

An ideal chemical preservative should have: 7

Answer 25

A wide range of antimicrobial activity
Non toxic to human beings and animals
Economical
No effect on the flavour, taste or aroma of the original food
Should not be inactivated by the food
Should not encourage the development of resistant strains
Should rather kill than inhibit microorganisms

Question 26

modified atmosphere

Answer 26

Controlled atmosphere packaging (CAP)
Modified atmosphere packaging (MAP)
Active packaging (AP)
Vacuum packaging (VP)

Question 27

ag of chemical preservatives in food

Answer 27

propionates, benzoates, sorbates, acetates, nitrites and nitrates

Question 28

propionates

Answer 28

used in bakery

Question 29

benzoates

Answer 29

used in jam jellies and fruits

Question 30

sorbates

Answer 30

antimicrobial additive in food as a spry in cheese dried food and bakery

Question 31

acetate

Answer 31

dehydroacetic acid to impregnate wrappers for disease to inhibit mold growth
acetic acid - vinigar used in mayonnaise ketchup and sauseages

Question 32

nitrite and nitrate

Answer 32

nitrite give stable red colour to meat but restricted because can form carcinogenic compounds

Question 33

drying- smoking

Answer 33

the smoke produces heat which kills some microorganism on the surface