Difference of Physicochemical Properties and Nutritional Quality between Raw and Extruded Foxtail Millet Flour

To investigate the effect of extrusion on the quality characteristics of foxtail millet flour,the differences of physicochemical properties and nutritional quality between raw and extruded foxtail millet flours were investigated systematically in the present study. The results showed that,the density of extruded flour(P<0.01)was extremly significantly lower than that of raw flour,while the particle size(P<0.01)and angle of repose(P<0.01)were extremly significantly higher than that of raw flour. The brightness(L^*)of extruded foxtail millet flour decreased,and the color(a^*)became darker and there was an obvious difference in color difference in color observed by the naked eye. Many low-threshold and high-contribution to flavor compounds,such as aldehydes,furans and pyrazines were produced during extrusion,which resulted in the flavor of extruded flour was better than that of raw flour. Aldehydes,especially hexanal(relative content was 34.58%)were the main flavor contributors of extruded foxtail millet flour. Compared with raw flour,the dry basis fat and amylose contents of extruded flour decreased by 28.92% and 28.21%,respectively. But the contents of polyunsaturated fatty acids increased by 21.08%,of which linoleic acid increased by 19.92% and linolenic acid increased by 63.40%. These results suggested that addation of extruded foxtail millet flour would enhance the flavor and taste,improve the texture and nutrition of foxtail millet-derived products.