How does Jam differ from Fruit Sauce?
Why does Jam "keep" better than Fruit Sauce?
Give method of sealing Canned Fruit and method of sealing Jam. Explain why different methods are used.
LESSON CLXIX
PROCESSING WITH MUCH SUGAR—JELLIES
EXPERIMENT 94: PECTIN IN FRUIT JUICE.—Put a few grapes, slices of apple, or cranberries in a small saucepan, and add enough water to cover and cook until the fruit is tender and soft enough to mash. Strain the cooked fruit through cheese-cloth.
Put 1 teaspoonful of the extracted fruit juice in a saucer, add an equal quantity of alcohol. [Footnote 126: Either grain (ethyl), wood (methyl), or denatured alcohol may be used. Both wood and denatured alcohol are poisonous. If they are used for testing, they should be handled and stored away with caution.] Mix by gently rotating the saucer. Let the mixture stand for 5 minutes. Then examine. What change has taken place in the fruit juice?
The formation of a solid mass in the mixture of fruit juice and alcohol which has stood for 5 minutes indicates that the fruit juice contains pectin,—a vegetable gelatine.
EXPERIMENT 95: PECTIN IN THE INNER PORTION OF ORANGE OR LEMON PEEL.—Cut away the yellow portion from orange or lemon rind. Cut or chop the white portion of the rind in small pieces. Cover with water and soak several hours or overnight. Then cook slowly for 1/2 hour. Strain and set aside to cool. To 1 teaspoonful of this liquid add an equal quantity of alcohol, and proceed as in Experiment 94. Does the lemon or orange rind contain pectin?
THE PRINCIPLE OF JELLY MAKING.—When the juices of certain fruits are extracted and cooked with sugar, the mixture stiffens when cool. This property of stiffening is due to the presence in fruit of two materials,— a certain carbohydrate, called pectin, and an acid. Pectin is like starch in that it stiffens when cold; but like sugar, in that it is soluble. Not all fruits contain pectin.