This section is from the book "Elements Of The Theory And Practice Of Cookery", by Mary E. Williams. Also available from Amazon: Elements Of The Theory And Practice Of Cookery; A Textbook Of Domestic Science For Use In Schools.
Gelatin is used for making many sweet jellies and desserts, also such jellies as mint jelly and tomato jelly. One ounce of gelatin will stiffen from three and one-half to four cupfuls of water in ordinary weather. In hot weather or on a wet day more is required ; in cold weather, less. If fruit is to be moulded in the jelly, use one and one-half ounces of gelatin.
First soften the gelatin by soaking in cold water,1 then dissolve it in boiling water, but never boil it. If stirred much while hot the gelatin may become stringy and refuse to jelly; for this reason, do not stir to help sugar dissolve, but keep the gelatin mixture hot by setting the bowl over hot water. Strain it through cheese-cloth or muslin doubled into a mould, and set it away to cool, in summer on ice. It will jelly in from three to six hours. The larger the proportion of gelatin to the liquid, the sooner it sets, but too much makes the jelly taste of gelatin, and also makes it tough. Use a mould of earthen or enamelled ware wet with cold water just before it is filled. See that it stands level while the jelly is cooling.
1 Cooper's gelatin softens in ten minutes; Knox's requires at least fifteen; some kinds take longer. Follow the directions on box. Granulated gelatin is more easily measured than that in sheets or shredded. A two-ounce box of granulated gelatin holds five tablespoonfuls. Manufacturers often use the spelling gelatine,
Gelatin, 1 oz., or if granulated,
2 1/2 tb. Cold water, 1/2 c.
Boiling water, 2 1/2 c. Sugar, 1 c. Lemon juice, 1/2 c.
Soak the gelatin in the cold water, add the boiling water, then the sugar, and stir till the latter is dissolved. Add the lemon juice, and strain through a cloth wrung out of hot water and laid over a wire strainer into a mould wet with cold water.
To vary the flavor, boil in the water one inch of stick cinnamon, and the thinly shaved peel (yellow only) of one or two lemons.
Serve these jellies turned out in a glass dish, with cream, whipped or unwhipped; or make them a little less stiff, and serve lightly broken up, as "Sparkling Jelly."
Gelatin is made from bone and hide, chiefly from scraps left from making bone buttons and skins from calves' faces. The gelatin is extracted from these by cooking them with water below the boiling-point. The solution of gelatin is filtered, concentrated, and cooled in large blocks. The blocks are sliced, and the slices dried on wire racks, and either powdered or shredded.2
1 Made with two tablespoonfuls of coffee to one cupful of water.
2 Analysis shows that some gelatin, especially the cheaper kinds, such as many bakers, confectioners, and ice-cream makers use, is impure and unsafe to eat. The best American brands are among the best made.
Although gelatin may serve as fuel and, in conjunction with other proteins, help to build tissue, it is not an important food. It is used because it provides a convenient way of serving other foods. (P. 141.)