金萱红茶茶膏加工工艺优化及挥发性成分分析

Optimization of Processing Technology and Analysis of Volatile Components in Jinxuan Black Tea Cream

摘要:

【目的】优化金萱红茶茶膏制备工艺，提升茶多酚含量，并比较不同加工方式对茶膏挥发性成分的影响。【方法】以金萱红茶干茶作为原料，利用响应面试验考察茶水比、酶添加量、超声功率和超声时间对红茶茶膏茶多酚质量分数的影响；并采用顶空固相微萃取（headspace solid-phase microextraction，HS-SPME） 结合气相色谱-质谱联用（gas chromatography-mass spectrometry，GC-MS）技术对真空冷冻浓缩（NP）、酶+真空冷冻浓缩（WB）和旋转蒸发浓缩+真空冷冻浓缩（B）3种不同加工方式下红茶茶膏中的挥发性成分进行检测分析。【结果】红茶茶膏的最佳工艺条件为茶水比1 g∶20 mL、酶添加量30 mg/g、超声功率514 W、超声时间21 min，此时金萱红茶茶膏中茶多酚质量分数为269.34 mg/g。从NP、WB和B中分别鉴定出103、107、84种挥发性成分，并在NP、WB和B中均检测到芳樟醇、苯甲醇、3-甲基丁醛、苯甲醛、苯乙醛、月桂烯和吡咯等呈花香、果香的挥发性成分；酶解后，WB比NP挥发性成分质量分数增加4 014.39 μg/kg，在B中未检测到3，7-二甲基-1，5，7-辛三烯-3-醇、柠檬烯、吡嗪类等呈花香、果香挥发性成分。【结论】酶解结合真空冷冻干燥能够提高红茶茶膏的挥发性成分质量分数。

Abstract:

[Objective]This study is intended to optimize the preparation process of Jinxuan black tea cream, enhance the content of tea polyphenols, and compare the effects of different processing methods on the volatile components of the tea cream.[Method]With dried Jinxuan black tea as the raw material, response surface methodology was adopted to examine the impacts of tea-to-water ratio, enzyme dosage, ultrasonic power, and ultrasonic duration on the mass fraction of tea polyphenols in the black tea cream. Furthermore, headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) was employed to detect and analyze the volatile components in the black tea cream samples processed via three distinct methods: vacuum freeze concentration (NP), enzyme-assisted vacuum freeze concentration (WB), and rotary evaporation concentration combined with vacuum freeze concentration (B).[Result]The optimal process conditions for the black tea cream were determined as follows: a tea-to-water ratio of 1 g∶20 mL, an enzyme dosage of 30 mg/g, ultrasonic power of 514 W, and ultrasonic duration of 21 min. Under these optimal conditions, the mass fraction of tea polyphenols in the Jinxuan black tea cream attained 269.34 mg/g. A total of 103, 107, and 84 volatile components were identified from NP, WB, and B samples, respectively. Among them, volatile components with floral and fruity aromas, including linalool, benzyl alcohol, 3-methylbutanal, benzaldehyde, phenylacetaldehyde, myrcene, and pyrrole, were detected in all the three samples (NP, WB, and B). After enzymatic hydrolysis, the mass fraction of volatile components in the WB sample was 4 014.39 μg/kg higher than that in the NP sample. The volatile components with floral and fruity aromas, such as 3,7-dimethyl-1,5,7-octatriene-3-ol, limonene, and pyrazines, were not detected in sample B.[Conclusion]Enzymatic hydrolysis combined with vacuum freeze-drying can effectively increase the mass fraction of volatile components in black tea cream.