Mo Xiaoli, Chen Yingyu, Zeng Zhen, Xiao Sui, Huang Yahui
College of Horticulture, South China Agricultural University, Guangzhou 510642, China.
Tea Research Institute of Hunan Academy of Agricultural Sciences, Changsha 410125, China.
Foods. 2024 Sep 30;13(19):3126. doi: 10.3390/foods13193126.
The level of consumption of summer tea is a problem in the development of China's tea industry. Current strategies to enhance the quality of summer and autumn teas primarily target the cultivation environment, with less emphasis on processing improvements. This study aimed to optimize the fermentation parameters to impact the quality of summer and autumn teas. We screened four strains of lactic acid bacteria (LAB) suitable for tea fermentation and determined their optimal mix. This optimized blend was applied to ferment summer and autumn teas. Through single-factor experiments, we evaluated the impact of various processing parameters, including the fixation method, rolling degree, inoculation amount, glucose concentration, fermentation temperature, and fermentation duration, on LAB growth and tea quality. The optimal processing conditions were established as microwave fixation, heavy rolling, an inoculation rate of 1.8% LAB, glucose addition at 8.8%, and fermentation at 36.5 °C for five days. Analysis revealed that the fermentation process significantly reduced the levels of polyphenols and ester-type catechins, which are associated with astringency and bitterness while enhancing the content of gamma-aminobutyric acid (GABA). Specifically, after five days, polyphenol content decreased by 26.89%, and GABA levels increased from 0.051 mg/g to 0.126 mg/g. The predominant aroma compounds in the fermented tea were alcohols with floral and fruity scents, constituting 54.63% of the total aroma profile. This research presents a methodical approach to reduce the astringency and bitterness of summer and autumn teas while concurrently increasing GABA levels.
夏茶的消费水平是中国茶叶产业发展中的一个问题。当前提高夏秋茶品质的策略主要针对种植环境，而对加工改进的重视较少。本研究旨在优化发酵参数以影响夏秋茶的品质。我们筛选了四株适合茶叶发酵的乳酸菌，并确定了它们的最佳组合。将这种优化后的混合物应用于夏秋茶的发酵。通过单因素实验，我们评估了包括杀青方法、揉捻程度、接种量、葡萄糖浓度、发酵温度和发酵时间等各种加工参数对乳酸菌生长和茶叶品质的影响。确定的最佳加工条件为微波杀青、重揉捻、乳酸菌接种率1.8%、葡萄糖添加量8.8%，以及在36.5℃下发酵五天。分析表明，发酵过程显著降低了与涩味和苦味相关的多酚和酯型儿茶素的含量，同时提高了γ-氨基丁酸（GABA）的含量。具体而言，五天后，多酚含量下降了26.89%，GABA含量从0.051毫克/克增加到0.126毫克/克。发酵茶中的主要香气成分是具有花香和果香的醇类，占总香气成分的54.63%。本研究提出了一种系统的方法来降低夏秋茶的涩味和苦味，同时提高GABA含量。
