Physicochemical properties of glutinous rice in the presence of alkali and borax

摘要

The influences of alkali, represented by sodium hydroxide (NaOH), and sodium tetraborate (borax) on the physicochemical properties of glutinous rice (RD6 cultivar) were investigated. The results showed that NaOH and borax treatment differently influenced the properties of glutinous rice. NaOH-treated flour (NTF) had the highest pH value, followed by borax-treated flour (BTF), and the control sample, respectively. NaOH caused a significant decrease in the protein content while borax had no effect. These results related to scanning electron micrographs of NTF which showed a smoother surface than that of the others. The BTF had the highest peak and final viscosity, possibly due to cross-linkages between borate ions and hydroxyl pairs on the polysaccharide chains. The results of pasting properties were in line with the hardness of the flour paste. Gelatinization temperature of both NTF and BTF was significantly higher than in the control, but enthalpy was not significantly different. This information provides a greater understanding of the behavior of NaOH and borax on glutinous rice and is useful for applications of NaOH and borax in food and non-food products. It is also important to understand borax's effect on starch and to find a suitable substitute.