2种形状桑芽绿茶中的1-脱氧野尻霉素浸出量及降血糖功效

1-Deoxynojirimycin Leaching and Hypoglycemic Effects of Two Forms of Green Tea Prepared with Mulberry Buds

将富含1-脱氧野尻霉素(1-deoxynojirimycin,DNJ)的桑树嫩芽加工成卷曲形和扁平形桑芽绿茶,检测2种形状桑芽绿茶在不同浸泡温度和浸泡时间下的DNJ浸出量,并通过动物试验评价2种茶汤的降血糖功效,探讨桑叶茶的加工形状和浸泡方法对其保健功效的影响。卷曲形与扁平形桑芽绿茶中的DNJ质量分数分别为0.113 2%和0.152 3%;浸泡温度对卷曲形桑芽绿茶中的DNJ浸出量没有显著影响,但扁平形桑芽绿茶以100℃水温浸泡时的DNJ浸出量最大;卷曲形桑芽绿茶的DNJ浸出量显著高于扁平形桑芽绿茶,浸泡9 min即可达到0.39 mg/g,且茶汤中的黄酮类、多酚类、游离氨基酸和可溶性糖等活性物质的浸出量也较高。2种形状桑芽绿茶的茶汤均能显著降低糖尿病模型小鼠的空腹血糖、餐后血糖和糖化血红蛋白浓度,且卷曲形桑芽绿茶的作用更为显著。试验结果表明,虽然卷曲形桑芽绿茶中的DNJ含量低于扁平形桑芽绿茶,但由于加工工艺的原因使茶叶中的DNJ浸出速率较快,DNJ等活性物质的浸出量也较高,能更有效地降低糖尿病模型小鼠的血糖指标,所以卷曲形桑芽绿茶更适宜作为降血糖保健食品。

In this study,mulberry buds rich in 1-deoxynojirimycin（ DNJ） were processed into curly-shaped and flat-shaped green teas. DNJ leaching amounts of these two forms of green tea at different soaking temperatures for different soaking time were determined,and the hypoglycemic effects of two tea infusions were evaluated through animal experiment to analyzethe effects of tea leaf shape and soaking method of mulberry leaf tea on healthcare function. The results indicated that the mass fraction of DNJ in curly-shaped tea and flat-shaped tea was 0. 113 2% and 0. 152 3%,respectively.The soaking temperature had no significant effect on DNJ leaching amount of curly-shaped tea,while the DNJ leaching amount of flat-shaped tea was the highest at 100 ℃. The leaching amount of DNJ in curlyshaped tea was significantly higher than that in flat-shapedtea,and reached a high level（ 0. 39 mg /g） at 9 min. In addition,the leaching amounts of flavonoid,polyphenol,free amino acid and soluble sugar in tea infusion of curly-shaped tea were high as well. These two forms of mulberry bud green tea could significantly reduce the concentrations of fasting and postprandial blood glucose and glycated hemoglobin in diabetic model mice,and the effect of curly-shaped tea was more obvious. The above results indicated that although DNJ content in curly-shaped mulberry bud green tea was lower than that in flat-shaped mulberry bud green tea,curly-shaped mulberry bud green tea had the higher DNJ leaching speed and leaching content of active substances including DNJ,and could effectively reduce the level of blood sugar in diabetic model mice. It was suggested that curly-shaped mulberry bud green tea is a better hypoglycemic healthcare food.