Effects of Microstructural Changes on the Phenolic Release Capacity, Volatile Profile and Color Property of Blueberry Pomace Powders at Multi-Grinding Scales

Blueberry pomace (BP) powders are rich in bioactive compounds and possesses a fruity aroma, making them promising food ingredients. Micronization can improve their microstructure, phenolic release, aroma, and color. This study applied coarse grinding and superfine grinding to produce BP powders with five distinct particle sizes at three scales: plant scale (>500 μm), tissue scale (100–500 μm) and cellular scale (10–100 μm). The results and a correlation analysis indicated that at an intermediate grinding between the tissue and cellular scale, the microstructural changes of the increasing particle porosity and decreasing particle size enhanced the phenolic release capacity. However, the phenolic contents in particles at the cellular scale decreased, attributable to thermal degradation from grinding. Furthermore, a total of 45 volatile organic compounds (VOCs) were identified. Notably, cellular grinding scale enriched both fruity and roasted aroma associated with the increasing pore volume (PV) and the specific surface area (SSA) and the decreasing particle size. In addition, grinding enhanced powder lightness and redness with the control. In conclusion, considering the microstructures, functional components, aroma and color, grinding at 20 min with the particle size mostly between 10 and 100 μm, with a small portion between 100 and 200 μm, is the preferred method for blueberry pomace.