BACKGROUND: Oil production from rice bran, an undervalued by-product of rice milling, produces defatted rice bran (DRB) as a waste material. Although it is considered a less valuable product, DRB still contains useful substances such as phenolic compounds with antioxidant, UV-B-protecting and anti-tumour activities. In this study the phenolic acids in DRB were extracted with subcritical water at temperatures of 125, 150, 175 and 200• C.
A facile solvent-free method to acetylate sago starch (Metroxylon sagu) is reported. Microwave (100 W) was used as the heating source and the heating time was varied from 2 to 10 min with the temperature of acetylation maintained at 1008C under continuous stirring. Using a 2 4 full factorial design of experiment, it was found that the degree of substitution (DS) of acetylated sago starch was strongly affected by the ratio of starch to acylating reagents, the ratio of acetic anhydride to acetic acid as the acylating reagents, the concentration of iodine as catalyst and reaction time. The physicochemical characteristics of the acetylated sago starch were assessed based on the FTIR spectra, the XRD spectra, the water absorption index (WAI), and the water solubility index (WSI). SEM was used to study the surface morphology of the acetylated sago starch at different DS.Abbreviations: DOE, design of experiment; DS, degree of substitution; WAI, water absorption index; WSI, water solubility index
Red Monascus rice (Ang-kak) is used as a traditional medicine and a natural colorant for food and beverages. Starch isolated from waste Ang-kak may compete economically with other common starch and give new value to this waste. Isolation by using alkaline method gave a product with a starch content of 81%. Impurities in the product are protein, fiber, ash, and secondary metabolites of the Monascus rice. Several physicochemical properties of the isolated starch were also investigated. It was found that 88.03% of the isolated starch is amylopectin. Thermogravitation study showed that the isolated starch degraded only slightly at temperature below 230°C and can be considered as a new source of starch for various applications.
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