Semi-continuous pressurized hot water extraction of black tea. (June 2018)

• Record Type: Journal Article
• Authors: He, Chunlan; Du, Hongfei; Tan, Chunbin; Chen, Zhong; Chen, Zeliang; Yin, Fengjun; Xu, Yuanjian; Liu, Xiaoling
• Is Part Of: Journal of food engineering. Volume 227(2018)
• Page Start: 30
• Page End: 41
• Publication Date: 2018-06
• Subjects: Extraction conditions -- Subcritical water -- Flavanols -- Caffeine -- Theophylline; Food industry and trade -- Periodicals; Food -- Analysis -- Periodicals; Aliments -- Industrie et commerce -- Périodiques; Aliments -- Analyse -- Périodiques; Aliments -- Recherche -- Périodiques; 664.005
• DOI: 10.1016/j.jfoodeng.2018.02.001
• Languages: English
• ISSNs: 0260-8774

Abstract

Abstract: The pressurized hot water extraction (PHWE) of six representative compounds from black tea brick was investigated in a semi-continuous extractor under the conditions of various temperatures (120–180 °C) and water flow rates (6–18mLmin -1 ). The extracted solutions were dark brown liquid suspensions, and a significant proportion of the six compounds (70.7–92.0%) was found in the supernatant phase after centrifugation. Theophylline is the most stable compound with respect to increasing temperature and extraction time. Epicatechin gallate (ECG) and epigallocatechin gallate (EGCG) were sensitive to temperature, while the other compounds (caffeine, catechin, and gallocatechin gallate (GCG)) were affected by both temperature and water flow rate. The optimum conditions were found to be 160 °C and 12 mL min −1 . Compared to the traditional tea brewing (TTB) method, PHWE can achieve significantly higher extraction yields of theophylline, caffeine, catechin, and GCG. Highlights: Theophylline is the most stable extracted compound at a high temperature and long extraction time. Temperature is the prime parameter for ECG and EGCG extraction and the 120 °C is preferable. Both the temperature and water flow rate significantly affect the extraction of caffeine, catechin, and GCG. In general, the optimum conditions are 160 °C and 12 mL min −1 .