Home Heat Treatments - Jam Making Flashcards
How is jam made?
By boiling fruit with a high % of sugar
What are the five main underlying principles of jam making?
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
What are the four main ingredients needed for jam making?
Fruit
Sugar
Pectin
Acid
Why is fruit needed in jam making?
Fruit contains pectin and acid which aids the setting of jam
List three fruits high in pectin
Apples
Blackcurrants
Oranges
List three fruits with medium levels of pectin?
Plums
Apricots
Blackberries
List three fruits low in pectin
Pears
Cherries
Raspberries
Describe the quality of fruit needed to make jam.
2
Fruits should be clean and free from blemishes or bruises
Good-quality, ripe, high-pectin, acidic fruits produce the best jams
Why is sugar needed to make jam?
2
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
How much sugar is needed in jam making?
Sugar should be weighed accurately to ensure there is 65% present in the jam
What type of sugar should be used when making jam?
Granulated sugar or jam sugar (contains pectin and fruit acid which assists the setting of jam)
What is pectin?
A polysaccharide found in the cell walls of ripe fruit
Why is pectin needed in jam making?
It is needed to set the jam
What form of pectin is found in under ripe fruit?
Protopectin
How can under ripe fruits be used in jam making if they only contain protopectin and not pectin?
The protopectin is converted to pectin when an acid is added
What form of pectin is found in over ripe fruits?
Pectic acid
Can over ripe fruit be used in jam making?
No as they only contain pectic acid and not pectin and therefore have no setting abilities
How can pectin be added to a jam?
Using high-pectin fruits e.g. apples, by adding commercial pectin or by using sure-set sugar
Why is acid needed in jam making?
4
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
Does acid need to be added to jams made of fruits such as oranges?
No as they are already acidic
What type of acid can be added to jams with a low acidic content?
Lemon juice
What are the three different ways to test if a jam has set?
Wrinkle test
Flake test
Thermometer test
What is the wrinkle test in relation to the setting of jam?
4 points
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
What is the flake test in relation to the setting of jam?
3 points
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
