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The study of the stability of anthocyanins in food colorant powder is important to predict the quality changes occurring as the food products are processed, to prevent and control the degradation of the anthocyanins. The objectives of this study were to identify anthocyanin components in natural food colorants obtained from black rice bran, and investigate their thermal stability at 60, 80, and 100°C, pH stability from 2.0 to 5.0 and also their correlation with visual color, L * , C * , and h°. Results showed that only six types of anthocyanins, cyanidin-3-O-glucoside, cyanidin-3-O-rutinoside, delphinidin, cyanidin, pelargonidin and malvidin were present in raw black rice bran (BRB) and black rice bran colorant powder (BCP). The thermal degradation of both the visual color and the anthocyanin content in the BCP followed a first-order kinetic reaction model. The temperature-dependent degradation was adequately fitted to the Arrhenius equation. In terms of the pH stability, increasing pH values resulted in lower activation energies (E a ) and higher half-life (t 1/2 ) values for both color parameters and individual anthocyanins when heating from 60 to 100°C. Moreover, the degradation rate constant (k) increased with increasing temperature and pH value. The degradation of cyanidin-3-O-glucoside and total anthocyanins showed a strong positive correlation with C * . The changes in visual color may be used as an on-line quality control indicator during thermal processing of food products containing rice bran colorants which have high anthocyanin content.

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In the production process of rice bran oil (RBO), the bran itself requires stabilization immediately after milling to protect against oil degradation from lipase. This study aimed to investigate the effects of stabilization and extraction methods on the chemical quality, bioactive content, and antioxidant activity of RBO. Steaming and ohmic heating (OHM) were used to stabilize rice bran before oil extraction using three extracting methods namely, immersion in n-hexane, Soxhlet, and an enzymatic method. The oil obtained from rice bran stabilized using OHM and extracted using the enzymes had the best chemical quality with the lowest values of FFA (1.51 ± 0.04%), highest level of γ-oryzanol (1190.1 ± 89.3 µg/g), and strongest total antioxidant activity (21.3 ± 0.32 mg AEE/g and 15.5 ± 0.24 mg BHAE/g). Results suggested that combination between OHM and enzymes is an effective process for the preparation of RBO and can be considered as an alternative extraction process.