柠檬酸甘薯淀粉酯制备工艺优化及性质研究

Preparation and Properties of Citric Acid-Modified Sweet Potato Starch

以甘薯淀粉为原料,优化制备高取代度柠檬酸淀粉酯的条件并对其性质进行研究。以柠檬酸淀粉酯取代度为指标,对影响取代度的因素进行研究,通过响应面优化制备工艺。得到最优工艺条件为pH1.5、反应温度148.21℃、反应时间6.45h、柠檬酸与淀粉干基质量比为0.59,在此条件下可制得取代度高达0.30的柠檬酸甘薯淀粉酯;柠檬酸甘薯淀粉酯具有很好的抗酶解性,抗性淀粉含量随取代度的增加而增加,当取代度达0.13时,抗性淀粉含量达92%;对比原淀粉,柠檬酸甘薯淀粉酯平均聚合度降低,白度先增高后降低。

In this study, sweet potato starch was reacted with citric acid to prepare modified starch with high degree of substitution （DS） by a dry heat method. Reaction conditions were optimized by response surface methodology to obtain maximum DS. The optimum reaction conditions were found to be reaction at 148.21 ℃ and pH 1.5 for 6.45 h with a citric acid-to-starch ratio of 0.59 （m/m）, resulting in a DH as high as 0.30. Citric acid-modified sweet potato starch exhibited high resistance to enzymatic hydrolysis. Resistance starch content increased with increasing DS, reaching 92% at a DS of 0.13. The average degree of polymerization decreased and the whiteness initially increased and then decreased compared with the native starch.