| Wheat germ is rich in different nutrients. It includes proteins, unsaturated fatty acids, a variety of vitamins, minerals and trace elements. It can be extracted for deep processing in wheat-milling industry. Fresh wheat germ contains high biological activity of lipase and lipoxidase, with easily rancid. The fresh wheat germ can’t store for long time. So it needs to be stabilized. In this paper, the extraction process of wheat germ was studied systematically in the cleaning section and flour section of wheat. It can provide the theory basis for improving and optimizing the existing extraction technology. At the same time, different nutritional quality of wheat germ also were studied in-depth with different stabilizing treatments. The results of the study were as follow:1. The technology parameters of wheat germ extraction in wheat cleaning section were studied. Best conditions were obtained: tempering time 18 h, tempering water 17% and corn grits machine speed 1150 r/min in the single factor experiment. The optimum conditions were obtained in wheat cleaning section with corn grits machine: tempering moisture16.04%, corn grits machine speed 1050 r/min, tempering time 21h; and the extraction rate of wheat germ was 1.32% under the optimum conditions.2. The crude fat contents of material grinding system and flour system had consistent results in wheat flour section extraction technology of wheat germ. The trend of front system materials were posterior than behind system materials. Crude fat content of front break system and reduction system materials had less than behind system materials. The highest crude fat content is 2T material. Adding 2T for the extraction of wheat germ, 1T and 2T were used for extracting wheat germ in the new extraction technology of wheat germ. The extraction efficiency of wheat germ was improved greatly in the theory.3. The color of the wheat germ got darker and the fragrance was fairly strong after different stabilizing treatment. In the meantime, the ash content changed little and the crude fat content slightly decreased, thus there was no significant difference between each other.The water content of wheat germ after the processing such as thermal drying, microwave and extrusion decreased in different extent, so the crude protein content increased accordingly.The acid value of wheat germ oil after different stabilizing treatment was significantly lower than the acid value of living embryos, the peroxide value of wheat germ oil was significantly higher than that of raw wheat germ, while the peroxide value of wheat germ oil after processing like microwave, atmospheric steam and extrusion was significantly lower than that of raw wheat germ. The fatty acid composition of wheat germ oil after different stabilizing treatment had no obvious changes, and the content of unsaturated fatty acid had little difference with that of living embryos. The palmitic acid of wheat germ after processing of heat drying, microwave, atmospheric steam and extrusion was reduced by 2%, 0.18%, 0.2%and 2% respectively. However, the content of oleic acid, linoleic acid and linolenic acid increased in different extent, although there was no significant change. Different stabilizing treatment had a certain influence on the content of essential amino acids in wheat germ, the loss of wheat germ lysine under processing of heat drying, atmospheric steam, microwave,and extrusion was respectively 0.5%, 0.3%, 0.3%, 0.3%, and the threonine of wheat germ increased by 0.1% after the thermal drying process, while the threonine losses of wheat germ after microwave, atmospheric steam, and extrusion processing were 0.5%, 0.3% and 0.5%respectively; the content of other essential amino acids didn’t change significantly after different stabilizing treatment. |
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