The High-Efficiency of Flexible Brushing Endows the Shelf Life of Brown Rice under Various Storage Conditions

Extending the shelf life of brown rice (BR) remains a bottleneck issue in the rice processing industry. Flexible brushing is a gentle physical treatment that removes surface bran powder while preserving the bran‑layer structure, representing a promising technique to mitigate brown‑rice quality deterioration. In this study, untreated BR and samples subjected to one (BRO), three (BRT), and five (BRF) times were stored for 60 days at 4 °C and room temperature. We then evaluated comprehensive indices including appearance quality, fatty acid value (FAV), lipase activity, volatile flavor compounds, and lipid composition. The application of flexible brushing significantly enhanced the appearance and cleanliness of brown rice; however, excessive brushing (3-5 times) led to a slight increase in the rate of broken rice and diminished preservation efficacy. After 60 days of storage, the BRO group demonstrated the most effective preservation among all brushing-treated groups: it inhibited the increase in free FAV by 31.80% at room temperature and by 40.74% at 4°C, while lipase activity was reduced by 18.66% and 14.02% under the respective storage conditions, compared to untreated BR. Moreover, integrated lipidomics and flavoromics correlation analyses elucidated the mechanisms underlying flavor deterioration in brown rice. These analyses revealed that free fatty acids, derived from the hydrolysis of glycerolipids and glycerophospholipids followed by autoxidation, were identified as primary precursors of off-flavor compounds. Thus, flexible brushing combined with low-temperature storage has been demonstrated to effectively extend the shelf life of brown rice and mitigate quality deterioration.