Abstract:

To investigate the changes of active components in Lycium chinense Miller leaf drink fermented by Aspergillus cristatum and its effect on antioxidant activity in vitro， L. chinense Miller leaves（GY） from three distinct production regions in Zhangzhou， Fujian （FZ）， Qingyuan， Guangdong （GQ）， and Nantong， Jiangsu （JN） were harvested. According to the black tea process，L. chinense Miller leaves were withered， rolled and naturally fermented to make L. chinense Miller leaf black tea（GC）. The black tea was fermented by A. cristatum for 2 days to obtain Fermented L. chinense Miller leaf black tea （GCF）. Compared with GY， GCF could improve the taste of L. chinense Miller leaves and remove the grassy flavor； the color of tea soup deepened from orange yellow to orange red； there was no significant change in the content of polyphenols and carotenoids. The content of flavonoids decreased significantly， and the content of flavonoids in JNGCF decreased by 43.44%. Compared with each group of GY， the contents of protein， total polysaccharides and total free amino acids in FZGCF， GQGCF and JNGCF were significantly increased. The protein increased by 50.70%， 49.07% and 55.34%， respectively； the total polysaccharide increased by 98.93%， 113.15% and 100.42%； the total free amino acids increased by 75.90%， 82.38% and 68.84%. In the in vitro antioxidant activity test， the DPPH free radical scavenging rate of FZGCF was significantly reduced， while there was no significant difference between GQGCF， JNGCF and their respective GY groups， and the reducing power of FZGCF， GQGCF and JNGCF was significantly reduced. The results showed that GCF groups could improve the taste， increase the redness of tea soup， preserve the original antioxidant active substances polyphenols and carotenoids to a large extent， and increase the nutritional substances protein， polysaccharides， and amino acids. The above results provide a theoretical basis for the development of functional products of L. chinense Miller leaf， filling the gap in L. chinense Miller leaf black tea products and reducing the resource waste rate of L. chinense Miller leaf.

Key words: Lycium chinense Miller leaves, black tea, antioxidant activity, active ingredient

摘要：

为了探究冠突曲霉菌（Aspergillus cristatum）发酵枸杞叶过程中，枸杞叶的活性成分变化及其对体外抗氧化活性的影响，采集福建漳州（FZ）、广东清远（GQ）、江苏南通（JN）3个产地的枸杞叶（GY），按照红茶工艺，经过萎凋、揉捻、自然发酵制成枸杞叶红茶（GC），接种冠突曲霉菌发酵2 d，获得冠突曲霉菌发酵的枸杞叶（GCF）。结果发现，与枸杞叶相比，冠突曲霉菌发酵枸杞叶红茶可以改善枸杞叶的口感，去除青草味；茶汤颜色加深，由橙黄色变为橙红色；多酚、类胡萝卜素含量无显著变化；黄酮含量显著降低，其中JNGCF黄酮含量降低幅度最小，下降了43.44%；与各组GY相比，FZGCF、GQGCF、JNGCF的蛋白质、总多糖和总游离氨基酸含量均显著升高。其中，蛋白质分别升高了50.70%、49.07%、55.34%；总多糖分别升高了98.93%、113.15%、100.42%；总游离氨基酸分别升高了75.90%、82.38%、68.84%。体外抗氧化活性实验中，FZGCF的DPPH自由基清除率显著降低，GQGCF、JNGCF与各自GY组无显著差异，且FZGCF、GQGCF、JNGCF的还原力均显著下降。结果表明，冠突曲霉菌发酵枸杞叶能改善口感，增加茶汤红度，能较大程度保留枸杞叶原有的抗氧化活性物质多酚和类胡萝卜素，并且增加营养物质如蛋白质、多糖和氨基酸的含量。以上结果为枸杞叶功能性产品开发提供了一定理论基础，填补了枸杞叶红茶产品的空白，降低了枸杞副产物枸杞叶的资源废弃率。

关键词: 枸杞叶, 红茶, 抗氧化, 活性成分