Jelly Making: Test for Pectin

Pectin is the substance in fruit that when combined with fruit acid and heated with sugar, causes the fruit juice to "jell." Some fruits contain little or no pectin, but most fruits and some vegetables contain it in varying amounts, and it is more abundant in underripe fruits than fully ripe fruits.

The Test
Mix 1 tablespoon of cooked unsweetened juice with 1 T grain alcohol. Wood or denatured alcohol may be used but should not be tasted as they are poisonous.

Juice rich in pectin will form a large clot.

Juices moderately high in pectin will form a few smaller clots.

Juice very low in pectin will form small flaky sediment.

These fruits are rich in acid and pectin:
Sour apples
Blackberries, sour
crab apples
cranberries
currants, red
gooseberries
grapefruit
grapes
lemons
oranges, sour
plums (most varieties)

These fruits are rich in pectin but low in acid
Sweet apples
Quinces

These fruits are high in acit but low in pectin:
Apricots
Cherries
Pineapples
Strawberries

The following fruit is low in both acid and pectin:
Raspberries
Elderberries
Peaches
Overripe fruits

Jelly Making: Adding the right amount of sugar

The amount of sugar to be added will depend upon the pectin and acid content of the juice. The only home method to determine the acid content of fruit juice is to taste it. If the juice tastes sweet, lemon or lime juice should be added.

For juices rich in pectin add 3/4 cup sugar per cup of juice.

For juices low in pectin add only 1/2 cup sugar per cup of juice.

The juice should be boiling when the sugar is added and the juice and sugar should be cooked as rapidly as possible until the jellying point is reached.

Overripe fruits are low in both acid and pectin.

Jelly Making: Test for the Jellying Point

Dip a cold spoon into the boiling syrup. At first when the spoon is inserted and raised above the steam you will observe a single drip formation (not illustrated). As the boiling fruit and sugar mixture nears the jellying point it will drop from the side of the spoon in two drops. When the drops run together and slide off the spoon in a sheet the jelly is finished and should be taken from the stove top immediately.

Thermometers are excellent for consistenly good results, but the sheet test should also be used, since the jellying point is not always the same. The range of temperature my vary from seven to ten degrees about the boiling point or 212 F at sea level.