Improving the functional and fermentation properties of black highland barley bran by airflow impact mill

Black highland barley bran (BHB) is rich in soluble dietary fiber. However, its physiological potential remains underutilized. Herein, an airflow impact mill (AFIM) was used to prepare BHB with varying particle sizes (37 μm–129μm), specifically achieving ultrafine grinding at the cellular scale. The effects of physical structural modification on the physicochemical properties, adsorption properties, and in vitro fermentation behavior of BHB were investigated. Results indicated that although hydration capacity of BHB decreased with increasing milling intensity, AFIM-induced ultrafine grinding ( D 50 =37 μm) significantly enhanced the cholesterol adsorption capacity of BHB in the intestinal milieu by 375% and achieved the maximum glucose diffusion retardation index of 32.52%. In vitro fermentation experiments revealed that microbial community structure was similar among BHB samples with different particle sizes, but ultrafine grinding significantly promoted metabolic activity, increasing acetic acid content by 48.54%. These findings suggest that AFIM-induced ultrafine grinding can significantly improve the functional properties of BHB through microstructural reconstruction, providing a scientific basis for the use of ultrafine BHB in functional foods. • Airflow impact mill (AFIM) achieved cellular-scale ultrafine grinding (<50 μm). • AFIM-induced ultrafine grinding redistributed pores in bran. • Ultrafine bran showed a 375% increase in cholesterol adsorption capacity. • Ultrafine bran showed increased acetic acid yield content (48.54%).