Application Research on Vacuum Pulsation-Ultrasonic Synergistic Extraction of Fu Tea

Abstract

This study was undertaken to develop an efficient industrial process for producing high-quality instant Fu tea powder using a novel vacuum pulsation-ultrasound assisted extraction (VP-UAE) method. The performance of VP-UAE was evaluated against four techniques—high-temperature extraction (HTE), low-temperature extraction (LTE), vacuum pulsation-assisted low-temperature extraction (VE), and ultrasound-assisted low-temperature extraction (UE)—using both unground and micro-ground Fu tea. Process parameters, including liquid-to-solid ratio, extraction time, and ultrasonic power, were optimized via single-factor experiments and Box–Behnken response surface methodology, with yield, tea polyphenol content, caffeine content, and sensory score as response variables. Compared to LTE, VP-UAE reduced the processing time by up to 60% and achieved superior overall product quality. The optimal extraction conditions were a liquid-to-solid ratio of 41:1 mL/g, an extraction time of 36 min, and an ultrasonic power of 165 W. Under these conditions, the yields of Fu tea powder, tea polyphenols, and caffeine reached 23.48%, 26.65%, and 31.25%, respectively, with a sensory score of 26.67. Notably, VP-UAE better preserved volatile aromatic compounds than traditional HTE. The synergistic effect of vacuum pulsation and ultrasonic cavitation facilitates efficient disruption of cellular structures, enhancing mass transfer at low temperatures. This work presents a novel, efficient, and high-quality technical approach for the industrial production of instant Fu tea powder.