Traditionally, peanuts were used as a source of oil and, even now, most of the world’s peanut production goes into cooking oils, margarines, and shortenings, as well as into the manufacture of soap and other industrial processes. Also called “arachis oil,” “nut oil,” or “groundnut oil,’ peanut oil is a colorless, brilliant oil, high in monounsaturates. Virgin oil is mechanically extracted (expeller pressed at low temperature [80-160° F]), and lightly filtered. This method provides the lowest yield but the highest-quality edible oil.
Refined oil is typically produced by solvent extraction. It is made from crushed and cooked peanut pulp, which is then chemically treated in order to deodorize, bleach, and neutralize the flavor of the oil. In the United States, only low-grade nuts are used for oil production. The fatty acid composition is quite variable for a number of reasons, such as genotype, geography, and seasonal weather (Holaday and Pearson 1974).When refined oil is stored at low temperature, a deposit is formed, and hence it cannot be used in salad oils and dressings.
Only peanuts that are free from visible mold and subject to less than 2 percent damage are used for edible purposes. In the United States and Western Europe, most peanuts to be eaten go into the “cleaned and shelled” trade and are consumed as roasted and/or salted nuts, as peanut butter, or as a component of confections.
Because of its high protein and low carbohydrate content, peanut butter was first developed in 1890 as a health food for people who were ill. It is a soft paste made from Virginia, Spanish, or other types of peanuts. The skin and germ are removed, and the kernels are dry roasted and ground. Salt, antioxidants, flavors, and sugars (dextrose or corn syrup) may be added after grinding. Hydrogenation and/or the addition of emulsifiers prevents separation. “Crunchy style” peanut butter has bits of roasted nuts mixed into it.
Peanut butter is approximately 27 percent protein, 49 percent fat, 17 percent carbohydrate, 2 percent fiber, and 4 percent ash. Its sodium content is approximately 500 mg per 100 g. Peanut butter has good stability even after two years of light-free storage at 80 degrees Fahrenheit (Willich, Morris, and Freeman 1954), and keeps longer if refrigerated. But sooner or later, it becomes stale and rancid.
Peanuts are frequently employed in the cuisines of China, Southeast Asia, and Africa. The residual high-protein cake from oil extraction is used as an ingredient in cooked foods and, in Chinese cooking, is also fermented by microbes.
In recent years, peanuts have been added to a variety of cereal - and legume-based foods to alleviate the problem of malnutrition. Moreover, peanuts in the form of flour, protein isolate, and meal in a mixed product have desirable sensory qualities (Singh and Singh 1991). Peanut flour is made by crushing the shelled, skinned nuts, extracting the oil, and grinding the crushed nuts. In India, the flour is used in supplementary foods, weaning foods, and protein-rich biscuits (Achaya 1980).
In addition, the peanut plant itself has a high nutritional value and can be used for livestock feed or plowed back into the soil to aid in fertilization of future crops (Cole and Dorner 1992). Nonedible nuts are processed into oil, with the cake used for animal feed. Peanut shells, which accumulate in abundance, can be used as fuel for boilers (Woodroof 1966).
World History
