Food applications, seed proteins

Solvents are also used in food processing. The largest uses are of aliphatic hydrocarbons, such as -hexane, which are important for oil seed extraction and purifying oils good solvency and ease of separation from the extracted oils (low boiling point) are key properties. Extraction is important in many other parts of the food industry to produce, for example, flavour extracts a variety of solvents from hydrocarbon to alcohols are used in such applications, but volumes are smaller. Isopropanol is used to extract fish protein from ground fish. Methylene chloride was used to extract caffeine from coffee, but has been largely superseded by liquid carbon dioxide. For all human food applications, food contact approval is vital if human consumption is involved. 

The extraction of s. seed goes through the normal procedure of so-called hard seed solvent extraction. The s. meal may undergo the normal procedures of feed production but may also be processed with special extraction methods for food applications, such as soymilk, soy protein concentrates and isolates, and several other soyfood products, or for cosmetic applications, such as protein hydrolysates (- hydrolyzed vegetable proteins). 

Composition and Uses. Soybeans are distinguished from other oil crops in that they only yield approximately 21% oil but 40-50% protein. Because of the high content in proteins soybeans historically have been a protein rather than an oil seed crop. The market for soybean products is largely driven by soy meal applications, more particularly by the food and the livestock feed industries (Figures 9.1.15 and 9.1.16). The majority of soy protein is a... 

The quality characteristics of the oil produced by the enzyme-assisted aqueous extraction process is comparable to that of conventional extraction procedures except in its phosphorus content (Table 12.5). The enzymatic process yields oil with less phosphorus which requires no or limited degumming. The crude oil from this process can be physically refined without further treatment (Laiho et al., 1991). Despite this improved quality of the crude oil which is an apparent cost saving in subsequent downstream processing, the enzymatic process has not been commercially exploited due to problems with yields. Considerable degree of emulsification occurs during the process. Approximately 18-25% of the available oil in the seed remains unrecovered in a standard operation. The discovery that the versatile protein, oleosin, binds approximately 20% of the oil in oil-bearing seeds (Tzen et al., 1990) has implicated this protein in the low yields associated with this process. Thus, the recoveries could be improved by the use of proteases. It has, however, been observed that successful application of proteases to improve oil recovery produces excessively bitter meals, repressing the potential utilization of the meal as feed or food. 

Grain seeds are rich sources of protein, almost always used for food, but potentially useful as chemical feedstocks for specialty applications. An exciting possibility just now coming to fruition in a practical sense is to transplant genes into plants so that they will make specialty proteins such as medicinal agents. 

For fiber production, h. is cut when the male plants are in full flower and shedding pollen. The subsequent retting and scutching processes are similar to those for - linseed and - flax. H. seed contains 32% oil, 25% protein and 20% starch. Seed of h. is also useful as food. The oil (rich in C18 2 and C18 3) was used for centuries as burning oil for lamps, and its leaves and flowers were used in pharmaceutical applications. After solvent extraction, the meal may be applied as animal feed. H. fibers are also being used for the manufacturing of paper and technical filters and for the pads of brakes and clutches as well as insulation, e.g., in house construction or in automobiles. 

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