Effects of Superfine Grinding on the Physicochemical Properties and Antioxidant Activity of <i>Puerariae Lobatae</i>

ABSTRACT The effects of airflow pulverization on the physicochemical properties and antioxidant activity of superfine pueraria powders were studied in this experiment. The purpose is to produce powders with different particle sizes by changing the operating pressure and the number of grinding cycles, adding grinding aids, including liquid nitrogen (LN), β‐cyclodextrin (β‐CD), and glycyrrhizic acid (GA), thereby improving their bioavailability and applicability in functional foods. The roots were coarsely crushed and then processed by air flow mill. The particle size distribution and morphology were analyzed by laser diffraction and scanning electron microscopy (SEM), and the span and breaking rate (Φ) were investigated. The chemical structure was analyzed by Fourier transform infrared spectroscopy (FT‐IR). The bulk density, sliding angle (β), water holding capacity (WHC), water solubility (WSI), swelling capacity (SC), and antioxidant activity were evaluated. The results showed that airflow pulverization significantly reduced the particle size, improved the uniformity of particle size, and increased the cell wall rupture rate; the extraction rate of puerarin from ultrafine powder crushed for 10 cycles at 0.4 MPa was the highest. These morphological changes lead to the enhancement of powder fluidity and water solubility index. It is worth noting that the ultrafine grinding process significantly improved the antioxidant activity without changing the chemical structure, which is attributed to the increased release of active ingredients after cell wall rupture.