塔宾曲霉液态发酵葡萄皮渣复配普洱茶的工艺优化及成分变化

Liquid-state Fermentation of Pu-erh Tea Blended with Grape Pomace by Aspergillus tubingensis: Process Optimization and Compositional Changes

摘要:

为了探讨葡萄皮渣对塔宾曲霉液态发酵普洱茶风味特性的影响，该研究基于大叶晒青绿茶与葡萄皮渣速溶粉的复配体系，通过单因素试验和响应面法优化发酵工艺参数，并系统考察了发酵过程中pH值、色差、总糖、蛋白质、总多酚及茶褐素等关键理化指标的动态变化规律。该文确定最佳工艺为：速溶葡萄皮渣粉添加量0.03 g•g-1，料液比1:30 g•mL-1，发酵时间144 h，孢子接种量1×106 CFU/mL。在该优化条件下，经144 h发酵后，茶汤pH值由4.66升至5.73；茶褐素含量由1.89 g•L-1增至5.40 g•L-1，蛋白质含量由0.06 g•L-1增至0.10 g•L-1，均呈上升趋势；而总多酚含量由6.10 g•L-1降至2.76 g•L-1，总糖含量由1.78 g•L-1降至0.96 g•L-1，均呈下降趋势。茶汤L*值降低，a*值和b*值升高，颜色变深变红。该研究为塔宾曲霉液态发酵高效制备葡萄皮渣复配普洱茶提供理论基础。

Abstract:

To investigate the effects of grape pomace addition on the flavor-related composition of Pu-erh tea fermented by Aspergillus tubingensis under liquid-state fermentation, a blended system consisting of sun-dried green tea leaves and instant grape pomace powder was established. Fermentation parameters were optimized using single-factor experiments and response surface methodology. Under the optimal conditions, dynamic changes in key physicochemical indices, including pH, color parameters, total carbohydrates, proteins, total polyphenols, and theabrownins, were systematically examined during fermentation. The optimal fermentation conditions were determined as follows: instant grape pomace powder at 0.03 g•g-1, a solid-to-liquid ratio of 1 g:30 mL, a fermentation duration of 144 h, and an inoculum size of 1×106 CFU/mL. Under these conditions, the pH of the tea infusion increased from 4.66 to 5.73 after 144 h of fermentation. Theabrownin content increased from 1.89 g•L-1 to 5.40 g•L-1, and protein content increased from 0.06 g•L-1 to 0.10 g•L-1, both showing continuous upward trends. In contrast, total polyphenol content decreased from 6.10 g•L-1 to 2.76 g•L-1, and total carbohydrate content declined from 1.78 g•L-1 to 0.96 g•L-1. Color analysis revealed a decrease in the L* value and increases in the a* and b* values, indicating a darker and redder appearance of the tea infusion during fermentation. These findings demonstrate that grape pomace addition significantly influences the compositional evolution of Pu-erh tea during liquid-state fermentation and provides a scientific basis for the development of flavor-enhanced Pu-erh tea products through the valorization of grape pomace.