Study on physicochemical properties and digestibility of glutinous rice and corn starch under enzymatic and anealing treatment

Abstract

Nowadays, the resistant starch plays an important role in preventing from the accumulation of fat, reducing diabetes, lowering the risk of heart disease, and giving positive effect on colonic health. This study was performed to investigate physicochemical properties of native and modified starches of glutinous rice (Oryza sativa L.) and corn (Zea mays L. var. ceratina) by using Pullulanase and annealing treatments. The native starch was isolated from glutinous rice and corn flour by using NaOH. As a result, all of native and treated products were determined A-type crystal and treated starches had higher swelling power and solubility than native ( At 90°C, swelling power of enzyme rice starch (5.16 g/g) and enzyme corn starch (8.35 g/g), and solubility by enzyme of rice and corn starch were similar (47%)). In addition, the resistant starch of both starches was increased after treated starches, and the treated of rice and corn starches had higher than native starches (treated rice starches (35.7%) and treated corn starches (38.47%)) Treated starches had smoother surface than native starch and rice starches (5μm to 10μm) had smaller size than corn starches (5μm to 20μm). Besides, both starches had maximum viscosity that were reduced in order of native > control > enzyme starches. Key words: Glutinous rice and corn, native starch, modified starch, isolated, annealing treatment, Pullulanase, solubility, swelling power, X-ray, SEM, Viscosity.