油莎豆发芽前后营养成分及多糖生物活性的变化

为考察发芽对油莎豆营养成分及油莎豆多糖体外抗氧化、降糖活性的影响，采用近红外光谱分析仪、氨基酸分析仪分析了发芽前后油莎豆淀粉、脂肪、蛋白质、纤维、灰分、氨基酸的含量，蒽酮硫酸法分析多糖含量；利用DPPH·、ABTS+·及总抗氧化能力评价油莎豆多糖抗氧化活性；采用PNPG法，以阿卡波糖作对照，分析油莎豆多糖体外降糖活性。结果表明，发芽对油莎豆各营养成分影响有一定差异，发芽后油莎豆的脂肪提高了8.22%，淀粉、蛋白质、纤维、灰分含量分别降低了11.75%、11.09%、10.31%和7.69%，氨基酸总量增加了8%；发芽后油莎豆多糖的得率增加了9.23%，同时发芽提高了油莎豆多糖的抗氧化、降糖作用等生物活性。高效阴离子交换色谱（HPAEC-PAD）技术分析结果表明，发芽改变了油莎豆多糖的单糖组成比例，产生了更多的抗氧化活性较强的单糖（鼠李糖）。相关性分析表明，油莎豆发芽后强的抗氧化能力、降糖作用与高的多糖含量呈极显著相关性（P<0.01，r=0.985~0.997），研究为油莎豆的深加工和功能化产品的开发提供重要的科学参考。

Analysis of Nutrient Composition and Bioactivity of Cyperus esculentus (C. esculentus L.) before and after Germination

To reveal the effect of germination on nutrient composition of C. esculentus L. and the antioxidant and hypoglycemic activity in vitro of its polysaccharide, a near infrared spectrometer and an amino acid analyzer were applied to analyze the content of starch, fat, protein, fibre, ash and amino acid while anthrone sulfuric acid method was adopted to determine the content of polysaccharides. DPPH·, ABTS+· and total antioxidant capacity were used to evaluate the antioxidant activity of C. esculentus L. polysaccharide while PNPG method was employed to observe the hypoglycemic effect of C. esculentus L. polysaccharide with acarbose as control. The results showed that the effects of germination on the nutritional components of C. esculentus L. were different, the fat contents of C. esculentus L. increased by 8.22% while amylose, protein, fibre and ash contents respectively reduced by 11.75%, 11.09%, 10.31% and 7.69% after germination. Furthermore, the total contents of amino acid improved by 8% while the yield of polysaccharides from C. esculentus L. was significantly increased by 9.23%. On the other hand, in the bioactivity assay, the results showed that the antioxidant and hypoglycemic activities of polysaccharides from C. esculentus L. after germination were higher than that of ungerminated. The analysis results of high performance anion exchange chromatography with PAD detector (HPAEC-PAD) showed that germination changed the monosaccharide composition ratio of C. esculentus L. polysaccharide, which produced more monosaccharides (rhamnoose, Rham) with stronger antioxidant activity. Correlation analysis showed that the strong antioxidant activity and α-glucosidase inhibitory activity of germinated C. esculentus L. polysaccharide were significantly correlated with high polysaccharides content (P<0.01, r=0.985~0.997). Mentioned above, our study would provide important scientific reference for the further processing and the development of functional products of C. esculentus L.