罗汉果果肉中糖类物质组成与含量分析

罗汉果果实中富含糖分,糖类物质的组成及其含量对果实的内在品质有重要影响,然而多年来对其品质的研究多集中在罗汉果苷上,果实中可溶性糖种类与含量迄今尚未见有系统地报道。该研究以干燥的罗汉果果实为材料,采用PMP柱前衍生化一高效液相色谱紫外检测法、高效液相色谱示差折光检测法分别检测果肉中可溶性糖的种类与含量,并进行方法学考察。结果表明:PMP柱前衍生化一高效液相色谱紫外检测法只能检出罗汉果果实中存在的2种还原性醛糖——葡萄糖、甘露糖;而高效液相色谱示差折光检测法则可一次性检出葡萄糖、果糖、蔗糖、棉籽糖、多糖5种糖分。与柱前衍生化法相比,高效液相色谱示差折光检测法更适合用来全面分析罗汉果果实中糖分的种类和含量。不同罗汉果品种果实中糖的组分一致,但含量有显著差别。另外,样品的干燥方式会影响果实中的总糖及各组分的相对含量。冻干果肉中蔗糖和葡萄糖相对含量最高,烘干则导致蔗糖和葡萄糖下降,果糖与多糖相对含量增加。

Determination of sugar components and contents

Components and contents of carbohydrates have important effects on fruit internal quality. Fruit of Siraitia grosvenorii is rich in sugars. However, researches on fruit quality mainly focus on mogrosides over the years,no systematic study about S. grosvenorii fruit carbohydrates and their monomer sugar constituents has been reported so far. In this study, dry fruit was selected as experimental material. PMP-pre column derivatization HPLC-UV detector method and HPLC-refractive index detector method were employed to determine the carbohydrates components and their contents of monomer sugar constituents in dried fruit flesh, and the methodological study was carried out. The results indicated only two kinds of reducing aldoses-glucose and mannose could be detected by PMP-pre column derivatization HPLC-UV detector method, while five kinds of carbohydrate: glucose, fructose, sucrose, raffinose and polysaccharide could be detected simultaneously by HPLC-refractive index detector method. As compared with PMP-pre column derivatization HPLC-UV detector method, HPLC-refractive index detector method was much more suitable for the general analysis of components and contents of carbohydrate in fruits of S. grosvenorii. Sugar components were the same while concentrations of each monomer sugar constituents were significantly different between different S. grosvenorii varieties. On the other hand, drying methods had obvious effects on the total sugars content as well as the relative contents of 5 kinds of sugar components. The relative contents of sucrose and glucose in freeze dried fruit flesh were much higher than those other 3 kinds of sugars. However, high temperature drying treatment resulted in significant decrease in sucrose and glucose concentrations, the relative contents of fructose and polysaccharide became the most.