支链聚合度对菠萝蜜种子淀粉老化特性的影响

Effect of the Degree of Polymerization of Amylopectin on the Retrogradation Properties of Jackfruit Seed Starch

摘要:

本研究以菠萝蜜种子淀粉（jackfruit seed starch，JFSS）为原材料，将其分离成直链淀粉和支链淀粉。将直链淀粉与五种不同支链聚合度的支链淀粉以1:1质量比进行混合，并进行糊化/老化处理，制备具有不同支链聚合度的老化JFSS（retrograded JFSS，RJFSS：M1’、M5’、M6’、M11’和BD’）。M1的支链聚合度最低，BD的支链聚合度最高。5种RJFSS样品显示出从致密到松散结构的显著变化。高脱水收缩形成致密结构，低脱水收缩相反。支链聚合度增加，5种RJFSS样品的Avrami指数和转变温度升高，重结晶速率、老化焓、老化度、相对结晶度、吸光度比降低。热力学特性、结晶结构和短程分子有序度的结果证实了不同支链聚合度RJFSS的老化特性。结果表明，支链聚合度是影响淀粉在贮藏过程中老化特性的重要结构因素。

Abstract:

In this study, jackfruit seed starch (JFSS) was used as the raw material and subjected to separation into amylose and amylopectin. The obtained amylose was mixed, at a mass ratio of 1:1, with five types of amylopectin with different degrees of polymerization, and the resultant mixtures were subjected to gelatinization / retrogradation to prepare retrograded JFSS with different degrees of polymerization of amylopectin (RJFSS: M1’, M5’, M6’, M11’, and BD’). M1’ had the lowest degree of polymerization of amylopectin, while BD’ had the highest. The five RJFSS samples varied significantly: from a compact structure to a loose structure. High syneresis led to the formation of a compact structure, whilst low syneresis had the opposite effect. Increasing the degree of polymerization of amylopectin raised the Avrami exponent and transition temperature, while decreasing the recrystallization rate, retrogradation enthalpy, degree of retrogradation, relative crystallinity, absorbance ratio of the five RJFSS samples. The results of the thermodynamic properties, crystalline structure, and short-range molecular order confirmed the retrogradation behaviors of RJFSS with different degrees of polymerization of amylopectin. All the obtained results indicated that the degree of polymerization of amylopectin is an important structural factor affecting the retrogradation behaviors of starch during storage.