principles of food preservation

Question 1

Control of ___________

Answer 1

temperature
e.g. pasteurisation
ultra-high temp treatment
freezing
canning/bottling

Question 2

Ultra-high temperature treatment

Answer 2

pasteurisation which is used mostly for treatment of milk and destroys
pathogenic bacteria
UHT: ultra heat treated milk which can lasts 6 months without refrigeration.

Question 3

Freezing

Answer 3

turns the water in food to ice so nearly all foods can be frozen.
increases shelf/storage life – inhibits microbes growth. but once defrosted they can become active again.
seal properly so that air does not cause freezer burn to the food product.
the faster food is frozen the smaller the ice crystals and the less damage
there is to cell structure of the food.

Question 4

Canning/Bottling

Answer 4

bacteria is killed at 100°C.
canning is a heat sterilisation process sealed so no micro-organisms can get in and then heated under steam pressure to 116-121°C.
can keep for up to 3 years as long as not damaged.
Bottling inhibits the access to oxygen that micro-organisms need to
grow and multiply.

Question 5

_________ breakdown of…

Answer 5

anaerobic breakdown of organic substances or nutrients

Question 6

Addition of…

Answer 6

addition of chemicals
salt
sugar
acid
artificial preservatives

Question 7

Salt

Question 8

Sugar

Answer 8

deprives micro-organisms of moisture as sugar attracts water which prevents microbial growth.
e.g. jam

Question 9

Acid

Answer 9

adding a chemical removes the oxygen from food which in turn inhibits or slows the growth of micro-organisms
prevents discolouration

Question 10

Artificial preservatives

Question 11

Removal of m…

Answer 11

removal of moisture
dehydration
freezing

Question 12

Removal of o…

Answer 12

removal of oxygen
organisms require moisture to survive and multiply and dehydration prevents this.
Moisture level reduced to between 5 – 25%

Question 13

Principles of food preservation

Answer 13

• control of temperature, such as pasteurisation, ultra-high temperature treatment, freezing, and canning or bottling
• anaerobic breakdown of organic substances or nutrients, such as fermentation
• addition of chemicals, such as salt, sugar, acid and artificial preservative
• removal of moisture through dehydration and evaporation
• removal of oxygen through vacuum packing