Food Preservation

Question 1

Advantages of preservation

Answer 1

Prevents waste
Makes out of season foods available eg frozen berries
Adds variety as new foods are produced
Saves money
Useful in unforeseen circumstances - meals already prepared

Question 2

Methods of home preservation and examples

Answer 2

Freezing eg veg
Heat eg jams
Chemical eg pickling
Dehydration eg herbs

Question 3

Underlying principle of freezing

Answer 3

Low temperatures inactivates microorganism growth and slows down enzyme action
Water converts to ice so microorganisms can’t use them

Question 4

Methods of home freezing

Answer 4

Quick - small ice crystals, little damage

Slow -large ice crystals, damage cell

Question 5

Suitable foods to freeze

Answer 5

Veg
Fruit
Bread
Meat
Fish
Soup

Question 6

Unsuitable foods to freeze

Answer 6

Mayonnaise (emulsion separates)
Who,e eggs (expand and crack)
Foods with High water content

Question 7

Advantages of freezing

Answer 7

Retains nutritional value colour flavour and texture
Saves time - meal prep
Saves money
Out of season food is available all year round
Avoids food waste

Question 8

Disadvantages of freezing

Answer 8

Initial cost of the freezer is expensive
Mill prep is time-consuming
Packaging is needed
Defrosting freezer can be time-consuming and laborious

Question 9

Guidelines for home freezing

Answer 9

Use fast freeze button
Cool food to room temp
Freeze in usable quantities
Blanch veg
Use airtight strong moisture proof containers
Leave room for expansion of liquids
Label and date
Store similar together
Put the older stuff to the front of the freezer
Avoid keeping freezer door open
Keep fridge full so the air doesn’t have to be cooled

Question 10

Guidelines for thawing food

Answer 10

Read cooking instructions
Call in freezer so bacteria can’t grow
Place on a plate to be thawed so juices don’t drop
Never re-freeze thaw the food

Question 11

Underlying principle of Jan making

Answer 11

Preserves fruit by boiling it at 100°C to the storm micro organisms and inactivates enzymes. Softens fruit. Adding sugar dehydrates microbial cells and they die. Pectin and acid set the jam

Question 12

Fruits with high pectin

Answer 12

Apples blackcurrants oranges

Question 13

Fruits with low pecten

Answer 13

Pears raspberries

Question 14

Setting tests for jam

Answer 14

Wrinkle test - jam will wrinkle when finger pushed through

Flakes test – should drip off spoon in a flake

Question 15

Underlying principle of chutney making

Answer 15

Same as jam making but addition of vinegar to preserve by lowering pH levels

Question 16

How to dehydrate at home

Answer 16

In a low temperature oven

Question 17

Types of commercial freezing

Answer 17

Blast freezing (blast of cold air)
Contact freezing (placed on cold metal plate)
Cryogenic freezing (sprayed with liquid nitrogen)
Fluidised bed freezing (blast of cold air from underneath)

Question 18

Methods of commercial heat treatment

Answer 18

Pasteurisation 
Homogenisation 
Sterilisation
Ultra heat treatment 
Canning

Question 19

stages in canning

Answer 19

FoodPrepared
Filled
Air removed
Sealed air tight
Sterilised by heat and cooled
Labelled

Question 20

What is fermentation

Answer 20

Breakdown of carbohydrates by microorganisms to produce carbon dioxide, alcohol and energy

Question 21

Types of commercial dehydration

Answer 21

Spray drying
Role of drying
Fluidised bed drying
Accelerated freeze drying 
Son drying

Question 22

What is irradiation

Answer 22

Exposing through to low-level is of radiation

The gamma rays passed through the food and destroy microorganisms

Question 23

Are there any radiation facilities in Ireland

Answer 23

No

Question 24

What is the radiation symbol called

Answer 24

Radura symbol

Question 25

Advantages of irradiation

Answer 25

Extends shelf life
Kills insect pests
Delays ripening of fruit and sprouting of veg
Retains colours, texture, flavour

Question 26

Disadvantages of irradiation

Answer 26

B and c vitamins destroyed
Chemical composition of high fat food changes as lipids become rancid
Misleading as food appears fresh
Free radicals form in food causing cancer