The influence of micronization on improving the phytoestrogenic effects of wheat bran was studied. Wheat bran samples were prepared by ball milling, and an animal experiment was carried out by feeding 8-month-old female rats wheat bran. The effect of wheat bran samples on serum estradiol (E2) and progesterone (P) levels of female 8-month-old rats was investigated. The wheat bran with a median diameter of 392.1 μm was micronized to 91.1 and 9.7 μm in median diameter by dry milling and wet milling for 5 hours, respectively. Microscopic observation and X-ray diffraction revealed more potential damage from wet milling than dry milling on the crystal structure of wheat bran granules. Almost all particles were dissolved and there was no obvious crystal peak in the 5-hour wet-milled wheat bran. The serum E2 and P levels of the 8-month-old rats fed wet-milled bran were increased significantly, 2.2 times higher than that of the same aged control group. The experimental results indicated that wet milling could destroy the crystal structure of wheat bran granules and improve the phytoestrogenic effects of wheat bran.
Keywords: dry milling; estradiol (E2); phytoestrogen; progesterone (P); wet milling; wheat bran.