food preservation

Question 1

what is food preservation

Answer 1

The conservation of food after harvest or slaughter for future consumption.

Question 2

name 5 ways of preserving foods

Answer 2

1. pickling- red onion
2. fermenting- kimchi
3. freeze drying- strawberries
4. sterilisation- milk
5. curing- mortadella/bonito flakes

Question 3

Why is food preserved? Give five reasons

Answer 3

1. Increase shelf life- extends the time a food product remains safe and consumable
2. Reduce microbial proliferation/multiplication of Salmonella, E. coli, etc.
3. delay ripening
4. Inhibit sprouting (root vegetables)
5. Lowering the TVC of bacteria and pathogens, TVC measures the total number of living microorganisms in a food sample.
   Preserving methods lower TVC, reducing both spoilage risk and foodborne illness.

Question 4

How to preserve food by preventing contamination?

Answer 4

. Aseptic technique when handling food
. Using manmade coverings to cover foods or natural coverings, like eggshells, fat, and fruit peel.

Question 5

How to physically remove microorganisms through preservation

Answer 5

. washing, trimming, sieving, filtering

Question 6

How is high temperature used for preservation

Answer 6

. When heat removes spoilage and pathogens, it doesn’t work on all microorganisms. It depends on the d value of the microorganism, which is the time it takes to kill 90% of all pathogens.

Question 7

How does boiling preserve food?

Answer 7

. When water reaches 100 degrees, it can kill pathogens.
. However, Clostridium bacteria spores can withstand heat, and there are thermophilic pathogens that can survive.
. It damages appearance an destroy vitamins

Question 8

how does blanching preserve food

Answer 8

. Helps remove soil and insects and reduces bacteria by 90%.
. prevents discolouration of bulky vegetables

Question 9

how can pasteurisation preserve food

Answer 9

. Milk is heated to 72 degrees for 15 seconds.
. This destroys bacteria without destroying vitamins and minerals.

Question 10

How does sterilisation preserve food

Answer 10

. under pressure steaming at 100 degrees. . kills all pathogens but destroys vitamins and minerals in the process, and changes sensory attributes.

Question 11

how can canning preserve food

Answer 11

. High temperatures kill all spores, swollen cans indicate microbial activity due to anaerobic respiration.

Question 12

how does low temperature preserve food

Answer 12

. Most bacteria cannot survive below -1.5 degrees, fridge must be around 0 to -5.

Question 13

How does freezing preserve food?

Answer 13

. Low temperature stops enzyme activity and reduces available water for microbial proliferation.
. Frozen food must be thawed thoroughly so there aren’t cold spots that don’t get cooked.

Question 14

How does dehydration preserve food?

Answer 14

. It reduces the amount of available water for microbial proliferation; most bacteria require 0.95 aw.
. However, some xerophilic bacteria, yeasts, and moulds can still grow; dehydrated foods don’t hydrate well.

Question 15

name three chemical ways of preserving food

Answer 15

. Salting- draws water out of microbes and lowers pH and enzyme activity.
. sugaring - draws water out of microscopic cells through osmosis, dehydrates microbes and lowers water activity.
. Smoking- exposes meat to phenols and acids and reduces water activity.

Question 16

name 3 additional ways of preserving

Answer 16

. fermentation
. irradiation
. modified atmosphere packaging