This section is from the book "Mrs. Allen's Cook Book", by Mrs. Ida C. Bailey Allen. See also: The Conscious Cook: Delicious Meatless Recipes That Will Change the Way You Eat.
Drying or evaporating may be accomplished entirely by artificial heat, or by a combination of sun and artificial heat. The former method is to be preferred as the weather is not always dependable. The reason that artificial heat is used in conjunction with the sunshine, is so that all insect eggs may be killed before the product is stored. The sun-dried products are darker in color, but have as good flavor.
The vegetables must be absolutely fresh, young and tender; they should be thoroughly washed and cleaned. Only well-scoured knives should be used in paring or cutting.
All vegetables should be blanched, as in canning by the new method, that is to say, they are prepared, placed in a wire basket, or cheesecloth bag, plunged into boiling water, for a given length of time, removed, drained and dried on towels, or by exposing them to the sun and air. This process insures a thorough cleaning, removes strong odors and flavors, softens and loosens the fiber and allows the moisture to evaporate more quickly and evenly. At the same time, the albuminous matter has been coagulated, thus hindering the escape of flavors.
The vegetable should then be spread in a thin layer on the trays. The temperature should be started at no° F. This can best be determined by an oven thermometer which can be secured at low cost. However, if one is not at hand, no° F. may be secured in most gas ovens by having the gas lighted for about two minutes. In most kerosene ovens, in about the same time, and in a coal oven by having a very low fire and the oven door a little more than half open.
The temperature should be gradually increased to 145o F. The length of time required for drying vegetables varies with the size and the amount of water they contain. Generally the process takes from two and a half to seven hours, most vegetables being completed in the shorter time. The products are dry when they are brittle.
The vegetables should be stirred, or turned, during the drying, trays should be moved from the lower part of the oven or dryer to the top to equalize the heat, and as the vegetables are dried two or more trays can often be combined, leaving space for a fresh lot, and making possible economy of both time and heat. If the oven is used, the door should be left slightly open.