酸解时间对大米淀粉结构性质的影响

以4种不同直链淀粉含量的大米淀粉(0%的优糯3号、10.90%的稻花灿、21.03%的聚两优、28.46%的华优香占)为原料,酸解处理不同时间,以酸解大米淀粉的酸解率、颗粒形貌、结晶性质、溶解度的变化为指标衡量不同酸解时间对大米淀粉结构及性质的影响。结果表明,不同直链淀粉含量的大米淀粉具有不同的耐酸性,酸解时间对不同直链淀粉含量大米淀粉的结构和性质有着不同的影响。大米淀粉酸解率与直链淀粉含量成反比,优糯3号为50%而华优香占仅为30%;所有淀粉颗粒在酸解后均产生一定程度的破碎,偏光十字变形直至消失,酸解相同时间,直链淀粉含量高的大米淀粉破碎率低;酸解未改变淀粉的晶型,仍为A晶型;随着酸解时间的延长相对结晶度增加;淀粉的溶解度随着酸解时间的增加而增大。

Effect of Acid Hydrolysis Time on the Structure and Properties of Rice Starches

In this study, four types of rice starch with different amylose contents ( Younuo 3: 0%; Daohuacan: 10.90%; Juliangyou: 21.03%; Huayouxiangzhan: 28.46%) were used to investigate the effect of acid hydrolysis time on the structure and properties of rice starches. After undergoing acid hydrolysis for different time, the changes in the hydrolysis ratio, particle morphology, crystallization properties, and solubility of hydrolyzed rice starches were measured and used as indicators to evaluate the effects of hydrolysis time. The results showed that rice starches with different amylose content shad different acid-resistant abilities, and thus hydrolysis time had different effects on the structure and properties of the rice starches with different amylose contents. The extent of acid hydrolysis in rice starch was negatively related to the amylose content, as evidenced by the fact that approximately 50% Younuo3 was hydrolyzed, whereas only 30% of Huayouxiangzhan was hydrolyzed. All starch granules showed a degree of breakage after acid hydrolysis, and the cross observed in starch under polarized light deformed before it completely disappeared. With the same acid hydrolysis time, the rice starches with higher amylose contents showed lower breakage rates. Acid hydrolysis did not affect the A-type crystal pattern of the starch in the studied samples; however, with increasing hydrolysis time the relative crystallinity and the solubility of the rice starches increased.