龙眼果肉干燥过程中多糖的理化特征与活性变化规律  

Changes of Polysaccharides in Longan Pulp during Drying:Physicochemical Properties and Biological Activities

作　　者：韩苗苗 姚娟 易阳 黄菲[2] 王丽梅 

机构地区：[1]武汉轻工大学食品科学与工程学院,湖北武汉430023 [2]广东省农业科学院蚕业与农产品加工研究所农业部功能食品重点实验室,广东广州510610 [3]武汉轻工大学生物与制药工程学院,湖北武汉430023

出　　处：《食品科学》2017年第21期67-73,共7页Food Science

基　　金：国家自然科学基金面上项目(31771979);国家自然科学基金青年科学基金项目(31301416);武汉轻工大学科研计划项目(2016J05)

摘　　要：探析龙眼果肉热风干燥过程中多糖的理化特性和生物活性变化规律。分离不同干燥阶段果肉中的多糖,通过对基本组成、傅里叶变换红外光谱图特征和相对分子质量分布的分析,比较其理化特征差异,结合体外抗氧化、抗肿瘤和免疫刺激效果评价比较其生物活性。随着干燥的进行,多糖中中性糖与蛋白质的质量分数比、葡萄糖和甘露糖物质的量比、游离氨基含量均呈逐渐降低的趋势,傅里叶变换红外光谱图的酰胺区特征吸收峰明显改变,高效分子排阻色谱的新高分子组分在干燥后期生成。而体外抗氧化活性评价发现,果肉干燥12~60 h,其多糖对1,1-二苯基-2-三硝基苯肼自由基清除能力、对羟自由基清除能力、总抗氧化能力得到明显增强(P<0.05);干燥12~24 h,对SGC7901和HepG2肿瘤细胞的生长抑制能力、刺激巨噬细胞一氧化氮和肿瘤坏死因子α生成的综合能力得到明显增强(P<0.05),但干燥60 h后有所减弱。不同干燥阶段多糖的生物活性差异可能与美拉德反应关联的多糖-蛋白质相互作用有关,结果可为龙眼干肉的高品质加工提供参考。This work aimed to investigate the changes of polysaccharides in terms of physicochemical properties and biological activities during the drying of longan pulp. Polysaccharides from longan pulp at different drying stages were isolated. The proximate composition, Fourier transform infrared spectroscopic characteristics and molecular weight distribution of polysaccharides were analyzed, and their antioxidant, antitumor and immunostimulatory activities were evaluated in vitro. With the increase of drying time, the physicochemical characteristics of longan pulp polysaccharides （LP） showed signifcant changes. The mass ratio of neutral sugar to protein, the molar ratio of glucose to mannose and free amino group content were decreased, the typical amide bands in the infrared spectrum were diverse, and new fractions with relative high molecule weight were formed at the advanced stage of drying process according to the high-performance size-exclusion chromatogram. The evaluation of in vitro biological activities indicated that various activities of LP such as 1,1-diphenyl-2-picrylhydrazyl radical scavenging, hydroxyl radical scavenging, ferric reducing antioxidant power increased after 12-60 h drying of longan pulp, inhibitory effects against tumor cells （HepG2 and SGC7901） and immunostimulating effects on nitric oxide production and tumor necrosis factor-alpha secretion in macrophages increased after 12–24 h drying of longan pulp. But the activities decreased after more than 60 h drying. These changes in activities might be related to the Maillard reaction between polysaccharides and proteins in longan pulp during drying. The results can be useful for the processing of dried longan pulp with high quality.

关 键 词：龙眼果肉 多糖 理化特性 生物活性 美拉德反应 

分 类 号：TS201.1[轻工技术与工程—食品科学]