甘薯块根可溶性糖组分特征及其与食味的关联分析

【目的】可溶性糖含量是甘薯块根食用品质和加工性能的重要指标,研究可溶性糖组分特征及其与食用品质的关系,有助于了解块根可溶性糖组分在加工中的变化及其对食味的影响,为甘薯鲜食与加工的品种选择、专用品种选育和种质资源利用提供依据。【方法】采用高效液相色谱蒸发光散射检测器法（HPLC-ELSD）测定102份甘薯种质资源的生薯和蒸熟薯的可溶性糖组分含量,对不同干物率类型的块根可溶性糖组分特征进行分析,并用相关性和逐步线性回归分析可溶性糖组分与食味的关系及其对食味的贡献。【结果】甘薯的生薯和熟薯均含有果糖、葡萄糖、蔗糖、麦芽糖4种可溶性糖。在生薯中,蔗糖含量最高,平均含量为25.79 mg·(g·FW)^-1,占生薯可溶性糖的45.31%;果糖和葡萄糖含量相近,关系密切,果糖含量（y）和葡萄糖含量（x）的拟合方程为y=0.807x+1.275;麦芽糖含量最低,平均含量为6.79 mg·(g·FW)^-1,仅占生薯可溶性糖的11.92%。生薯可溶性糖含量高低主要由果糖和葡萄糖含量决定,通常情况下,低干物率品种具有更高的生薯可溶性糖和果糖含量,生化甜度更好。在蒸熟过程中块根中可溶性糖含量变化主要在于产生了大量麦芽糖,麦芽糖含量从生薯的0.96—24.67 mg·(g·FW)^-1提高至14.80—136.16 mg·(g·FW)^-1。熟薯可溶性糖含量高低是由麦芽糖含量决定的,中、高干物率类型具有更高的熟薯可溶性糖和麦芽糖含量。甘薯块根食味增量主要来源于蒸熟过程中产生的可溶性糖;麦芽糖、果糖、蔗糖是甘薯块根食味的重要影响因子;麦芽糖对食味增量的贡献率近50%,对香味和质地的作用尤为突出;果糖对黏度的贡献最大,而蔗糖对质地的贡献优于果糖。【结论】生薯可溶性糖和果糖含量是反映甘薯生薯甜度的重要指标,熟薯可溶性糖、麦芽糖含量是反映甘薯食味的重要指标。麦芽糖、果糖、蔗糖是影响甘薯块根食用品质及加工性能的重要可溶性糖组分。筛选出甘薯块根可溶性糖特异种质11份。

Analysis on the Characteristics of Soluble Sugar Components in Sweetpotato Storage Root and Its Relationship with Taste

【Objective】The soluble sugar content in sweetpotato storage root is an important indicator of edible quality and processing performance. The study on the characteristics of soluble sugar components and their relationship with edible quality can help to understand the changes of soluble sugar components and their influence on taste during processing, providing a basis for the selection of varieties for table use and processing, and breeding and utilization of germplasm resources for special use. 【Method】 The content of soluble sugar components in raw and steamed storage roots of 102 sweetpotato germplasm were determined by high performance liquid chromatography with evaporative light scattering detector (HPLC-ELSD). The characteristics were analyzed according to dry matter content types, and correlation and stepwise linear regression were used to analyze the relationship between soluble sugar components and taste and their contribution to edible quality. 【Result】 There were four soluble sugars of fructose, glucose, sucrose and maltose in both raw and steamed storage roots. In the raw storage root, the sucrose content was the highest, with an average content of 25.79 mg·(g·FW)^{- 1}, accounting for 45.31% of the soluble sugar. The fructose and glucose content were similar and closely related, and the fitting equation for fructose content (y) and glucose content (x) was y = 0.807x + 1.275. The maltose content was the lowest, with an average content of 6.79 mg·(g·FW)^-1, which only accounts for 11.92% of the soluble sugar. The content of soluble sugar in raw storage root mainly depended on the fructose and glucose content. Generally, the varieties with low dry matter content had higher content of soluble sugar and fructose in raw storage root, and the biochemical sweetness was better. During the process of steaming, the changes of soluble sugar content were mainly due to the production of a large number of maltose, which increased from 0.96-24.67 mg·(g·FW)^-1 of raw root to 14.80-136.16 mg·(g·FW)^-1. The content of soluble sugar in steamed storage root was determined by the maltose content, and the variety types with medium or high dry matter content had higher content of soluble sugar and maltose. The improvement of taste quality mainly attributed to the increasing soluble sugar content during the process of steaming. Maltose, fructose and sucrose were the important factors affecting the taste quality, and maltose contributed nearly 50% to the increase of taste quality, particularly to the flavor and texture. Fructose content contributed the most to the viscosity while sucrose contributed more to the texture than fructose. 【Conclusion】 The content of soluble sugar and fructose in raw storage root was an important indicator to evaluate the sweetness of raw sweetpotato. The content of soluble sugar and maltose in steamed storage root was an important indicator to evaluate the edible quality of sweetpotato. Maltose, fructose and sucrose were the important soluble sugar components that determined the edible quality and processing performance of sweetpotato. In this study, 11 sweetpotato germplasm with specific soluble sugar in storage root was selected.