Physicochemical Properties and Flavor Components of Four Foxtail Millet Bran Fractions

Millet bran with different degrees of milling was used as raw materials, the differences in nutritional composition, physicochemical properties, and volatile components of different foxtail millet bran fractions were explored by measuring nutritional composition, water distribution, hydration characteristics, chromaticity, gelatinization characteristics, and volatile components. The results showed there were significant differences in content of fat, protein, ash, starch, and water among the four types of foxtail millet bran (S1–S4). S3 millet bran contained 10.96% protein and 26.05% fat, with the highest nutritional value. Meanwhile, S3 millet bran had excellent characteristics such as strong fluidity, strong foaming ability (5.54%), and high stability (82.86%), but high content of water and oil were not conducive to the storage of S3 millet bran. Correlation analysis shows that starch and protein directly affected the processing properties of millet bran (hydration characteristics, foaming properties, etc.). In addition, 72, 47, 70, and 51 volatile substances were detected in the four types of millet bran (S1–S4), respectively. There were 10 different volatile substances in 4 types of millet bran. Six compounds including methyl hexanoate, hexanal, and methyl palmitic acid had the highest content in S1 millet bran, and the other 4 compounds including dodecane and n-hexanol had the highest content in S2 millet bran. The odor activity value (OAV) of nonanal in four types of millet bran was 702, 444, 110, and 51, respectively, which could be used to effectively distinguish these foxtail millet bran fractions. This study is conducive to the precision separation process and selective use, which can maximize the utilization of resources.