Effects of roasting on storage degradability and processing suitability of brown rice powder
Miho Fukui, Md Zohurul Islam, Hsi‐Mei Lai, Yutaka Kitamura, Mito Kokawa
Abstract
To screen the best roasting condition for development of new roasted brown rice products, c.f., roasted brown rice slurry, the storage stability and processing suitability of roasted brown rice powder were studied. In this study, roasted brown rice (BR) powders were prepared with different roasting levels of raw, light roast, medium roast and dark roast. Analyses of roasted BR powder's color, degradability (moisture content, water activity, and acid value), antioxidant activity, processing properties (pasting properties and thermal properties) were carried out. Lower L* value and higher a* value was observed with higher roasting levels. Degradability significantly improved in roasted samples and dark roasted sample showed the lowest water content and acid value though water activity value was the most favorable in light roasted sample (0.2< aw <0.4). Furthermore, antioxidant activity became significantly higher in roasted samples and dark roast showed the highest activity even after 4 wk of storage (21.1–25.9%). In terms of processing suitability, the increased pasting temperature and decreased peak viscosity were observed upon roasting. Advantageously, dark roasted sample showed highest cooling and heating stability. Overall, dark roasted sample showed the best storage stability and functionality, thus, selected as an optimal roasting level.