Effects of Storage Conditions on Nutraceutical Levels in Rough Rice1

During rough rice storage, changes occur in physicochemical and functional properties of the rice kernel, a process often referred to as aging. This study was conducted to determine how storing rough rice at different moisture contents (MCs) and temperatures over a range of storage durations can impact the nutraceutical content of the rice kernel. Rough rice (‘Cypress’, ‘Cocodrie’, ‘XL6’, ‘XP1003’, and ‘XP1005’) was dried to three MC levels: 10%, 12%, and 14%, and then stored at 21oC for six months. Within the 12% MC lots, XL6 and Cypress were stored at two additional temperature levels, 7oC and 38oC, for six months. Subsamples of rice were taken every four weeks and the rice milled for 30 s to collect bran for analysis of nutraceutical content. Nutraceutical content in bran increased within the first 2 to 3 months of storage and then decreased for the following 4 to 6 months of storage. Hybrid rice (XL6, XP1003, XP1015) generally contained lower levels of nutraceuticals compared to Cocodrie and Cypress. INTRODUCTION As rough rice is stored, changes occur in physicochemical and functional properties including water absorption, stickiness, and paste viscosity (Chrastil, 1990; Swamy et al., 1978); this process is known as aging of rice (Hamaker et al., 1993; Perdon et al., 1997). Most of the research regarding the aging process has focused on starch, protein, and lipids with few studies concentrating on the beneficial health components of