两种乙酰化马铃薯淀粉流变及凝胶特性的对比研究

Comparative study on rheological and gel properties of two kinds of acetylated potato starch

以马铃薯淀粉为原料,用两种乙酰化试剂(乙酸乙烯和乙酸酐)分别制备乙酰化淀粉,对比研究两种乙酰化马铃薯淀粉的流变和凝胶特性.结果表明:与原淀粉相比,乙酰化增强了马铃薯淀粉糊的热稳定性,增大了其触变性,其中乙酸酐乙酰化淀粉的热稳定性更好,触变性更强.在较低浓度(6%)时,乙酰基团对淀粉糊化和流变特性的影响比较高浓度(8%、10%)时更为明显.原淀粉凝胶的网络结构强度最大且最为均匀(113μm～198μm),乙酰化淀粉凝胶的网状结构强度较低,易被破坏,凝胶的网孔尺寸在较大的范围内变动(9μm～276μm).相比于原淀粉,乙酰化淀粉形成凝胶的能力较差,两种乙酰化淀粉之间差异不大.乙酸乙烯乙酰化淀粉凝胶的冻融稳定性最好,其次是原淀粉凝胶,而乙酸酐乙酰化淀粉凝胶最差.

With potato starch as raw material, the acetylated potato starch were respectively prepared by two acetylation reagents （vinyl acetate and acetic anhydride）. The rheological and gel properties of two kinds of acetylated potato starch were compared. Results showed that compared with the original starch,acetylation enhanced the thermal stability of potato starch paste and increased its thixotropy. The acetic anhydride acetylation starch had better thermal stability and stronger thixotropy. The effect of acetyl group on gelatinization and rheological properties of starch at low concentration （6%） was more obvious than that at high concentration （8% and 10%）. The network structure of the original starch gel was the strongest and the most uniform （113 μm^198μm）. The network structure of the acetylated starch gel was low in strength and easy to be destroyed. The pore size of the acetylated starch gel varies in a large range （9 μm^276 μm）. Compared with the original starch,acetylated starch had a poorer gel forming ability,and there was little difference between the two acety lated starches. The freeze thaw stability of vinyl acetylated starch gel was the best, followed by the original starch gel,and that of acetic anhydride acetylated starch gel was the worst.