In making jelly the pure juice of the fruit is extracted then cooked with sugar till it reaches the jelly stage.

Underripe fruit is the best to select for jelly. In some cases green fruit, such as green grapes, may be used.

Pectin

The element in fruit juice that causes it to jelly is called pectin, but to make a perfect jelly the juice must also be acid. Certain fruit juices such as peach, while they contain pectin will not jelly because of the lack of acid. This can often be supplied by adding some fruit acid such as citric, or tartaric acids.

Proportions

The amount of sugar varies somewhat with the acidity of the fruit, but in general the proportions are three-fourths to one part sugar, to one part fruit juice.

Fruit juice can be made to jelly without the addition of any sugar, but it requires long boiling, will be dark in color and unpalatable. An over proportion of sugar however will keep it from jellying, making it syrupy or may result in the formation of crystals.

Time of Boiling

The time of boiling depends on the concentration of the fruit juice, the proportion of sugar, and pectin, and in all probability the degree of acidity.

If the fruit juice is very dilute it should be boiled before the sugar is added, to concentrate it, so that the cooking after the sugar is added will not be too long. But the concentration should not be so great that the boiling after the sugar is added is not long enough to change the form of sugar. Too long (an hour or more) or too short, (5 m) boiling may result in the formation of sugar crystals.

Apple And Mint Jelly

Wash and cut into small pieces 4 lbs. of Greening apples, and put into a granite sauce pan. Wash and chop quite fine enough mint to fill one cup, and add to the apples. Add enough water to keep from burning, and cook until the apples are tender and fall to pieces. Then strain, pressing the bag to extract the juice. Use 3/4 c sugar to each c of juice. Cook until about ready to jelly, then add 4 t lemon juice, and enough color paste to make a delicate green, and pour into glasses.

Creme de Menthe cordial may be used if the fresh mint cannot be obtained, adding enough to give the desired flavor.

Combination For Jellies

For combinations of fruits that are ripe at different times, such as apple and raspberry, strawberry and apple, blackberry and quince, currants and peaches, extract the juice of the fruit that is ripe first, bring to the boil, put into sterilized jars or bottles and seal. Then when the other fruit is ripe make the jelly according to directions given above for jelly making.

Apple and quince in equal parts make an excellent jelly.

Rose Geranium Jelly

Make apple jelly, place a rose geranium leaf in the bottom of each glass, and pour on the hot jelly. The geranium leaf will rise to the top. If one desires a delicate flavor remove the leaf at once. A very strong flavor, too strong to be desirable, will result if the leaf is left in the glass.

Test For Jelly

The quick test, and one which proves to be very accurate after experience, is the sheeting (that is, dropping in a whole transparent sheet) from the spoon.

The cooling test should be used by the inexperienced person, or if there is any doubt. This consists in putting a spoonful of the jelly on a sauce dish, and cooling quickly on ice or otherwise to see if it jellies. In using the latter test, which necessarily takes a few minutes, the kettle of jelly should be set back so that the cooking is retarded, as those few minutes might carry it beyond the right point.

In using a thermometer the best temperature to stop the boiling ranges from 221° to 223° F. If the jelly does not set quickly, place it uncovered in the sun for a few hours.