Influence of commercial polishing method on the structural, crystalline, and functional characteristics of rice (Oryza sativa) during aging

Abstract

Rice polishing is a vital stage in its processing, while aging is a complex process that starts pre-harvest and continues until the rice is consumed. As rice ages, substantial changes take place in its properties. This study investigates the changes in structural, crystalline, and functional properties of selected rice varieties (BPT 5204, GGV 05 − 01 and GNV 10–89) to understand the impact of polishing during the ageing process. The outcomes of scanning electron microscopy (SEM) illustrated significant structural changes of polyhedral starch molecules, forming complex with cell wall, resulting in the disappearance of the particle shape and sharp edges. The crystalline properties of selected rice varieties analyzed with X-Ray diffractograms revealed that significant changes in crystal size, d-spacing and percent crystallinity. These were in the ranges of 164.89 to 231.48 A^º and 136.07 to 207.94 A^º for crystal size, 4.32 to 5.17 A^º and 4.16 to 4.75 A^º for d-spacing and 32.36 to 49.73% and 34.30 to 51.47% for percent crystallinity, for before and after polished rice samples, respectively. However, the FT-IR analysis depicted the effect of ageing as an increase in intensity for peaks corresponding to each functional group for one-year-old rice samples compared to fresh rice in all the varieties for both brown and polished rice samples. This research aligns with the UNs Sustainable Development Goals (SDGs), particularly Goal 2: Zero Hunger, by enhancing our understanding of rice quality and storage, along with Goal 12: Responsible Consumption and Production, by improving post-harvest processing techniques to maintain rice quality.