ผลของกระบวนการผลิตต่อคุณภาพของสตาร์ชข้าวเหนียว / สุพัตรา งามอุรุเลิศ = Effect of processing on the quality of glutinous rice starch / Supatra Ngamurulert
The effects of milling methods, type and concentration of protein extraction solutions on the quality of glutinous rice (RD6) starch were investigated. Three milling methods (dry, wet, and mix milling) and three protein extraction conditions (aqueous solutions of sodium hydroxide at 0.2-0.5%, sodium carbonate at 1-4%, and dodecylbenzene sulfonate (DoBS) at 0.9-1.5%) were used. The physicochemical properties and thermal properties of the flours and starches were analyzed. The results from the chemical analysis showed that the RD6 contained 89.70% carbohydrate, 89.40% total starch, 9.30% protein, 0.52% ash, 0.23% fat, 0.29% fiber, and 5.56% amylose content. The wet-milled flour had the lowest % protein, % yield, and % damaged starch, and had the highest % total starch (p [is less than or equal to] 0.05). From the rheological measurement using the Rapid Visco Analyser (RVA), it was found that the wet-milled flour had the highest peak viscosity and breakdown and had the lowest setback and pasting temperature. The results from the physicochemical measurement of starches showed that all wet-milled starches had the lowest % protein, % fat, % fiber, % ash, and % damaged starch while the dry-milled starches had the lowest % carbohydrate, % total starch, and % yield. Increasing the concentration of extract solution would decreased % yield, % protein, % fat, and % fiber in the starch, but increase % ash, % carbohydrate, % damaged starch, and % total starch. Starches obtained from all conditions had the similar amount of % amylose content (p>0.05). From the RVA, it was found that the wet-milled starches had the highest peak viscosity and breakdown and the lowest setback. The peak viscosity decreased as the concentration of the extract solution increased. Results from the thermal analysis using DSC showed that the wet-milled starches had the lowest peak temperature with the highest enthalpy of gelatinization and there was no significant difference on the onset temperature of each starch (p>0.05). Increasing concentration of extract solution would increase the peak temperature. Finally the wet-milled starches had the highest freeze-thaw stability.