Physicochemical and functional properties of Thai organic rice flour

Abstract

Rice flour can be applied into many kinds of foods, but it can have an effect on the final product quality . This study aimed to assess the properties of four different types of rice flours, namely Thai organic white (Phitsanulok; PRF), colored (Riceberry; RBF), brown Jasmine (BJF), and red Jasmine (RJF). The chemical composition (moisture, ash, crude fat, protein, fiber, and carbohydrate contents) of all samples were significantly different ( p < 0.05). PRF contained the highest amylose content (33.80%) ( p < 0.05). The highest peak (4067.33 cP) and breakdown viscosities (2077.33 cP) were observed in BJF ( p < 0.05) whereas the highest setback (1551.33 cP) was found in PRF ( p < 0.05). The onset, peak, and conclusion temperatures were significantly different ( p < 0.05) while gelatinization enthalpy were not significantly different ( p > 0.05). The highest water absorption (7.14 g/g) and water solubility indexes (7.05%) were found in colored rice flour ( p < 0.05) (RJF and BJF, respectively). Ultimately, higher amylose content resulted in lower gelatinization temperature and in percentage of crystallinity, but there was an increasing setback value for PRF. Meanwhile, low amylose content in colored rice flour promoted high values of gelatinization temperature, pasting (peak and breakdown viscosities), and functional properties (water solubility index). • Differences were observed in the physicochemical and functional properties of Thai organic rice flours. • The variations are a result of various factors such as the proximate composition, amylose content, etc. • Low amylose flours gave higher values of pasting properties. • The morphology of starch granule was not affected by their chemical compositions. • Higher crystallinity in pigmented rice flour was caused by higher numbers of amylopectin branches.