Textural, nutritional and aromatic characteristics of fragrant rice in relation to milling degrees

Abstract

Kam Sweet Rice (KSR) is a unique fragrant rice variety with excellent taste quality in Guizhou Province in China. However, overprocessing leads to the loss of flavor and nutrients. Herein, the effects of different degrees of milling (DOMs) (0%–15.0%) on the texture, nutritional quality, and aroma properties of KSR were investigated. As DOMs increased, the brightness (L∗) values of rice raised, while the red/green (a∗) and yellow/blue (b∗) values decreased. Twenty-one volatile compounds were identified in KSR using gas chromatography–mass spectrometry. The unique flavor compounds 2-acetyl-1-pyrroline, hexanal, nonanal, octanal and 2-pentylfuran were found in brown rice. With an increase in DOM, the types and contents of most fragrant volatiles decreased. Textural analysis showed that the hardness and chewiness of the cooked KSR decreased but cohesiveness and springiness increased with an increase in DOMs. The peak pasting viscosity increased by 20.76% when the DOM was changed from 0% to 15.0%. With the removal of protein, lipid, and dietary fiber, the in vitro digestibility increased by 9.98% after 180 min compared with brown rice. These findings could provide accurate estimation of DOMs and could promote moderate processing of fragrant rice.