高支化修饰木薯淀粉及产物的理化性质研究

Study on Highly Branched Modification of Tapioca Starch and the Physicochemical Properties of Its Products

摘要:

木薯淀粉在食品工业中应用广泛，但通常需要经过改性才可用于食品中。相较于传统的改性手段，酶法改性因环保安全、副产物少、产物得率高等优点成为淀粉领域的研究热点。采用来源于极端嗜热菌Rhodothermus obamensis STB05（R. obamensis STB05）的淀粉分支酶（GBE）对木薯淀粉进行高支化修饰，并分析了高支化修饰对木薯淀粉分子结构、稳定性及体外消化性能等理化性质的影响。结果表明，在酶添加量为100 U/g、反应时间为12 h的条件下对木薯淀粉进行改性，所得产物中α-1，6糖苷键摩尔分数达到7.85%，比天然木薯淀粉增加152.41%；木薯淀粉分子中长链比例降低，短链比例上升，平均链长降低。木薯淀粉糊液的稳定性研究表明，经高支化修饰后，木薯淀粉糊的溶解度、凝沉性、透明度稳定性及冻融稳定性等性质均有不同程度的改善，且体外消化性能提高。该研究结果为木薯淀粉生物改性及其工业化应用提供了理论依据。

Abstract:

Tapioca starch is widely applied in the food industry. However, it usually requires modification before it can be used in food. Compared to traditional modification techniques, enzymatic modification has become a research hotspot in the field of starch due to its environmental friendliness, minimal by-product generation, and high yield. In this study, a starch branching enzyme(GBE) derived from the extreme thermophilic bacterium Rho-dothermus obamensis STB05 (Ro-GBE) was used for the purpose of catalyzing the highly branching modification of tapioca starch. The effects of this modification on the molecular structure, stability, and in vitro digestibility of cassava starch were systematically investigated. The results showed that after modification with an enzyme dosage of 100 U/g and a reaction time of 12 h, the resulting product exhibited an α-1,6 glycosidic bond ratio of 7.85%, which represents an increase of 152.41% over that of native tapioca starch. Additionally, the ratio of long-chain molecules in the modified starch decreased, while the short-chain proportion increased, and the average chain length was reduced. Furthermore, stability tests on tapioca starch paste indicated that the highly branched modification improved properties such as solubility, precipitation stability, transparency stability, and freeze-thaw stability. The results from the in vitro digestion experiments revealed a reduction in the digestibility of the modified starch. These findings provide a preliminary theoretical basis for biological modification of tapioca starch and its industrial application.