Home Heat Treatments - Jam Making

Question 1

How is jam made?

Answer 1

By boiling fruit with a high % of sugar

Question 2

What are the five main underlying principles of jam making?

Answer 2

Fruit is boiled at 100 degrees Celsius to destroy microorganisms and inactivate enzymes

Boiling softens fruit by breaking down their cell walls

65% sugar is added which creates a concentrated sugar solution which draws water out of microbial cells by osmosis which dehydrates and kill microorganisms

Pectin and acid is present which changes the watery fruit liquid into a set jam, pectin or acid can be added if there is not enough present naturally in the fruit

The jam is sealed at the end which prevents the re-entry of microorganisms

Question 3

What are the four main ingredients needed for jam making?

Answer 3

Fruit
Sugar
Pectin
Acid

Question 4

Why is fruit needed in jam making?

Answer 4

Fruit contains pectin and acid which aids the setting of jam

Question 5

List three fruits high in pectin

Answer 5

Apples
Blackcurrants
Oranges

Question 6

List three fruits with medium levels of pectin?

Answer 6

Plums
Apricots
Blackberries

Question 7

List three fruits low in pectin

Answer 7

Pears
Cherries
Raspberries

Question 8

Describe the quality of fruit needed to make jam.

2

Answer 8

Fruits should be clean and free from blemishes or bruises

Good-quality, ripe, high-pectin, acidic fruits produce the best jams

Question 9

Why is sugar needed to make jam?

2

Answer 9

Sugar preserves jam by creating a concentrated sugar solution which draws moisture out of microbial cells by osmosis causing them to dehydrate and due

Sugar also sweetens the jam

Question 10

How much sugar is needed in jam making?

Answer 10

Sugar should be weighed accurately to ensure there is 65% present in the jam

Question 11

What type of sugar should be used when making jam?

Answer 11

Granulated sugar or jam sugar (contains pectin and fruit acid which assists the setting of jam)

Question 12

What is pectin?

Answer 12

A polysaccharide found in the cell walls of ripe fruit

Question 13

Why is pectin needed in jam making?

Answer 13

It is needed to set the jam

Question 14

What form of pectin is found in under ripe fruit?

Answer 14

Protopectin

Question 15

How can under ripe fruits be used in jam making if they only contain protopectin and not pectin?

Answer 15

The protopectin is converted to pectin when an acid is added

Question 16

What form of pectin is found in over ripe fruits?

Answer 16

Pectic acid

Question 17

Can over ripe fruit be used in jam making?

Answer 17

No as they only contain pectic acid and not pectin and therefore have no setting abilities

Question 18

How can pectin be added to a jam?

Answer 18

Using high-pectin fruits e.g. apples, by adding commercial pectin or by using sure-set sugar

Question 19

Why is acid needed in jam making?

4

Answer 19

To release pectin from the cell wall of fruits

To convert protopectin into pectin

To improves the colour and flavour of jams

To help prevent crystallisation

Question 20

Does acid need to be added to jams made of fruits such as oranges?

Answer 20

No as they are already acidic

Question 21

What type of acid can be added to jams with a low acidic content?

Answer 21

Lemon juice

Question 22

What are the three different ways to test if a jam has set?

Answer 22

Wrinkle test
Flake test
Thermometer test

Question 23

What is the wrinkle test in relation to the setting of jam?

4 points

Answer 23

A plate is placed in the refrigerator until cool

One teaspoonful of jam is placed on the cool plate for one minute until cool

Push the jam with your fingertip

If the jam wrinkles it has set

Question 24

What is the flake test in relation to the setting of jam?

3 points

Answer 24

Dip a spoon in jam and allow it to cool for one minute

Tilt the spoon and allow the jam to run off

If the jam has set it will fall from the spoon in one large flake

Question 25

What is the thermometer test in relation to the setting of jam?

Answer 25

Place a sugar thermometer into the pot of jam , if it reads 105 degrees Celsius the jam has set

Question 26

What is crystallisation in relation to jam making?

Answer 26

When sugar granules fail to dissolve throughout the jam

Question 27

What causes crystallisation of jams?

3 points

Answer 27

If there is more than 65% sugar added

If the jam has not been boiled for long enough

If the sugar is not stirred continuously to ensure it is dissolved fully before boiling

Question 28

What causes a jam to not set?

3 points

Answer 28

Insufficient pectin or acid

If jam is not boiled for long enough to release pectin from the cell walls of the fruit

If jam is poured into pots before the setting point has been reached

Question 29

What is fermentation in relation to jam making?

Answer 29

The breakdown of jam by microbes which produces an off-flavour

Question 30

What causes fermentation of a jam?

3 points

Answer 30

If insufficient sugar is added

If poor-quality fruit is used

If the jam is not boiled for long enough