Physical and chemical properties of indigenous brown rice and brown rice flour in upper northeast

Abstract

The objective of this research was to study the physical, chemical, nutritional value, and antioxidant activities of native rice varieties that have been certified and are popularly grown in the northeast of Thailand. The rice varieties used in this study were Mali Dang Gomain (MG), Tabtim Chumphae (TCP), Maled Fai (MF), Rice Berry (RBR), Kam Feuang (KF), Niew Dam Hmong (M), and PSRR line. The quality study results on cooked brown rice showed that the hardness of seven varieties varied between 260.76 and 700.63 g, with Maled Fai having the highest hardness (700.63 g). The solubility of non-glutinous rice flours (Mali Dang Gomain, Tabtim Chumphae, Maled Fai, Rice Berry) was lower than that of glutinous rice flours (Kam Feuang, Niew Dam Hmong, PSRR). The swelling power of seven varieties varied between 2.54 and 4.96. Viscosity is an important physical quality when analyzing pasting characteristics. It was found that the pasting temperature was in the range of 59.70–68.70 cP, and the pasting temperature was related to the amount of amylose. Maled Fai flour had the highest amylose content of 22.24% and also had the highest pasting temperature (68.70^oC). Niew Dam Hmong had difficulty undergoing retrogradation readily due to the fact that brown rice flour had the lowest breakdown (30.26 cP) and the lowest setback from trough (8.78 cP), which meant brown rice flour had high stability that made it suitable for food processing, which required high stirring and heat. The analysis of nutritional value showed the Rice Berry had the highest protein and vitamin B1 content at 8.28% and 0.1998 mg/100g, respectively. Niew Dam Hmong contained the highest amounts of vitamin E and iron (Fe), 0.13 mg/100g and 18.82 mg/kg, respectively. Niew Dam Hmong also had antioxidant capacity, total phenolic compounds, and anthocyanin content of 1,311.51 mg ascorbic acid/100 ml,