Page:Foods and their adulteration; origin, manufacture, and composition of food products; description of common adulterations, food standards, and national food laws and regulations (IA foodstheiradulte02wile).pdf/435

 by treatment with steam. Details of this deodorizing process vary and are regarded as trade secrets. The oil so prepared is largely used in the preparation of substitutes for lard and similar cooking fats. Such oil is a great improvement over the ordinary summer yellow and bleached oils, but falls short of being an ideal oil.

Within the last few years a cottonseed oil has been put on the market in which the objections to the use of cottonseed oil as food have been as nearly overcome as the chemical nature of the oil will permit. The oil produced by this process is practically odorless and tasteless and can be used satisfactorily for all culinary purposes. Large quantities are used by the bakers in place of lard. (David Wesson.)

Further Details.—The cotton seed from various sources is put through a screen to take out the bolls and coarse material. The seed is then put through a gin to remove as far as possible any remaining lint, of which about 20 pounds per ton of seed are obtained. The clean seed is next sent to a huller composed of revolving cylinders covered with knives, which cut up both seed and hull. The chips are then conveyed to a screen placed on a vibrating frame, through which the kernels fall. The hulls are carried by an endless belt to the furnaces, where they are burned. The kernels of the seed are conveyed to crusher rolls, where they are ground to a fine meal. The meal is then sent to a heater, where it remains from twenty to forty minutes. These heaters have a temperature of 210 to 215 degrees F.

The hot meal is formed into cakes by machinery; these are wrapped in cloth and placed in the press. About sixteen pounds of meal are put in each cake. The cakes are placed in a hydraulic press, where a pressure of from 3,000 to 4,000 pounds per square inch is applied. The press is also kept warm. The expressed cakes contain only about 10 percent of oil. The cake is sold as cattle food or for fertilizing purposes. The crude oil as thus expressed contains about 1.5 percent of free acid, also a notable quantity of water and solid matters in suspension. The manufacture of cottonseed oil usually takes place in the winter months immediately after the ginning of the cotton is completed. The oil is likely to become rancid if kept unpurified until the hot months. The crude oil is collected in oil tanks at the press and shipped to the refining houses. In winter time when tanks are sent to the north where the temperature is very low the contents of the tank become solid unless protected from the action of the cold.

Refining Process.—The first step in the refining of a crude cottonseed oil is to have it stored in large and deep tanks where it remains at rest for a proper length of time. During this period of rest the heavy mechanical impurities and water settle to the bottom of the tank and are typically known as "foots." The oily portions of these fats are used in the manufacture of soap and for other technical purposes. The tanks may be connected with steam jackets in order to