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.
