A. Trial Jelly.
Place in saucepans one-half cup of crab apples and one-half cup of pears or peaches, cutting them into pieces. Just cover with water, later adding more if necessary. Cover and boil, until fruit is soft and will mash easily. Make a jelly bag out of double cheesecloth by folding and sewing it in the shape of a cornucopia; and, when the fruit is done, allow it to drip through the bag, at first without squeezing. Examine juice, then squeeze the remainder through and note the difference.
1. Place in glass cups one teaspoon of each juice obtained, and add an equal amount of alcohol. Let it stand five minutes. Observe the pectin, the substance which furnishes the thickening for jelly. Compare the amounts found.
2. Now try to make jelly out of the rest of the two extracts by adding to each an amount of sugar equal to three-fourths of the amount of the juice, and boiling until it is determined whether the mixture will "jell."
Tests for jellying:
Place a few drops of jelly on a cold plate and put in a cold place. When it is done the drops should harden over the surface and wrinkle when scraped with a knife or spoon. While making the test, remove the jelly from stove to prevent over-cooking.
Perhaps the best, because the quickest, test is to allow a little of the juice to drop from the spoon. When the mixture is done, these drops should jelly and break off.
Composition of Fruits and Fruit Products.
B. To Make Jelly.
Make grape jelly, using one cup of material. The grapes should be picked over and washed before being put into the saucepan. It is not necessary to add more water. After the sugar is added to the juice, remove any scum that forms. Sterilize the jelly glasses before filling. When the jelly has hardened, cover with melted paraffin.
Because fruit juices differ so much in their composition, it is impossible to give general directions sufficiently exact always to insure a perfect jelly. In fact, perfect jelly is rather seldom made. To be ideal it should not only be beautifully colored and transparent, but so tender that it cuts easily, and firm enough to keep its shape, but not so firm that it does not quiver.
In order to make jelly, fruit juices must contain two substances, acid and pectin, and these should be present in proper proportion. When fruit is cooked, pectin is formed by the action of water and heat on a substance called pectose which is present in the raw fruit. This pectose is closely related to cellulose1 and probably is closely associated with it in the cell walls of the fruit. It is absolutely unlike cellulose, however, in its property of being affected by boiling water. The pectin which is obtained from the pectose is the substance which gives texture to our jellies. It is possible to make jelly by great concentration without the addition of any sugar at all to the fruit juice, but the jelly that is formed is tough and gummy and not palatable, as well as being much less in amount than is produced ordinarily. The addition of sugar in the presence of the right amount of acid seems to precipitate the pectin and make the jelly set.
1Cellulose is the chief substance of which the cell-walls of plants are composed.
Not only does one fruit differ from another in the amount of these two substances which it contains, but different lots of the same kind of fruit may differ materially. As fruit ripens it contains less acid, and less pectin as well, and over-ripe fruit may fail to jelly at all. Fruit that is not fully ripe is much safer to use than that which is overripe. Some fruits contain too much acid, unless they are diluted with water, but it is quite possible to add so much water that there is neither enough pectin nor enough acid present. As a rule, very juicy fruits need have only sufficient water added to prevent burning. When they are soft enough to mash easily, the whole is transferred to a cheesecloth bag wrung out of hot water, and the juice is allowed to drip through. If the pulp is squeezed, the resulting juice is not so clear, but the flavor is not changed. Less juicy fruits must be covered with water while they are cooked. The alcohol test for pectin may be relied upon to tell whether the proper concentration is obtained.
The amount of sugar used, like the water, varies with the kind of fruit. It is better to err on the side of using too little, rather than too much. Jelly made from currants and grapes that are rather green may have as much as one part of sugar to one part of juice, but, in general, three-quarters of the amount of the juice is the right proportion of sugar. If at any time the alcohol test does not show plenty of pectin, lessen the amount of sugar. Too much sugar not only will give a jelly which is very sweet, but may give one that is syrupy. The amount of acidity can, perhaps, be as well judged by taste as in any other way. Before the sugar is added, the fruit juice should be distinctly tart.
Jelly can be made from fruits that are lacking in acid by the addition of some acid of vegetable origin, such as tartaric or citric. This does not always improve the flavor. The acid is commonly added by stewing with such fruits some other fruit which will supply the lacking acid.
Most housekeepers do not realize that if fruit is allowed to drip and is not squeezed through the jelly bag, the pulp may be returned to the kettle and boiled with more water, which gives additional extractions. The last should be concentrated until the alcohol test shows the right proportion of pectin. The first extract is usually made into jelly by itself, because it has the finest flavor, while the subsequent extractions are worked up together. Some-times even a fifth extraction, if it contains sufficient pectin to make it worth while, can be made.
The time necessary for making jelly differs with different fruits, with the amounts of pectin and acid present, and with the proportion of sugar used. The jelly, however, should be made as quickly as possible. If the fruit is allowed to simmer, too long heating of the pectin with the acid may entirely destroy this substance. For this reason the sugar is heated before it is added to the juice; if it cools off the mixture, the whole must be cooked a longer time.
There are three ways of making jelly. In one, the sugar is added at once to the fruit juice; in another, the fruit juice is boiled for sometime before the sugar is put in; while in the third, it is put in when the fruit juice has cooked about half the total time necessary for making the jelly. Probably the third of these methods is the best.
After the jelly has hardened, it may be covered in the old-fashioned way by cutting a piece of paper which will just fit into the top of the jelly glass, and dipping it into alcohol or brandy, placing this directly on the jelly, and then covering the top of the glass with another piece of paper large enough to tie or paste down. The alcohol is used to prevent the growth of molds, spores of which may have settled on the surface while the jelly was cooling and forming. The outer piece of paper is used to prevent the access of fresh spores and to lessen evaporation. A somewhat easier method is to pour a layer of melted paraffin over the top of the jelly. The paraffin should be hot, so as to kill any germs which may be present. If, in cooling, the paraffin shrinks from the side, leaving a crack between it and the glass, more paraffin should be poured in.
Jelly keeps best in a cool, dry place. Since the color of fruit sometimes fades, it is well to keep jellies and fruits where they are not exposed to too much light.
Cornell Reading Course for the Farm Home. Vol. 1, No. 15.
"Principles of Jelly-Making." U. S. Farmers' Bulletin No. 203. "Canned Fruits, Preserves, and Jellies." U. S. Farmers' Bulletin No. 388. "Jelly and Jelly Making."
1. Why should not saucepans or spoons made of aluminum, or tin, be used in cooking fruit?
2. Why should jelly bags be dipped into hot water before being used?
3. Why are jelly glasses put in hot water, or on a cloth wet in hot water before filling?
4. Why, in jelly-making, is fruit not quite ripe preferred to fruit over-ripe?
5. Why is jelly covered after making?
6. Where is it best to store jelly for keeping?
7. Make a list of fruits which are good for jelly-making and star those that are so juicy as to require no water added in the making.
8. Make a list of combinations of fruits that would make good jelly.
9. Compare the cost of the canned fruit and jelly made in the laboratory or at home with that of the commercial products.