Preprint Article Version 1 This version is not peer-reviewed

Effect of Ultrasonic-assisted and Microwave-assisted Technology on Bioactive Compounds and Aroma Quality of Instant Green Tea

Version 1 : Received: 2 March 2020 / Approved: 3 March 2020 / Online: 3 March 2020 (11:38:20 CET)

How to cite: Zhou, X.; Fu, X.; Fu, Z.; Ye, X. Effect of Ultrasonic-assisted and Microwave-assisted Technology on Bioactive Compounds and Aroma Quality of Instant Green Tea. Preprints 2020, 2020030041 (doi: 10.20944/preprints202003.0041.v1). Zhou, X.; Fu, X.; Fu, Z.; Ye, X. Effect of Ultrasonic-assisted and Microwave-assisted Technology on Bioactive Compounds and Aroma Quality of Instant Green Tea. Preprints 2020, 2020030041 (doi: 10.20944/preprints202003.0041.v1).

Abstract

The production of instant green tea requires hot-water extraction, which is time consuming and contributes to losses in aromatic compounds. In this study, an ultrasonic-assisted technology was used to improve the extraction efficiency of green tea, thereby shortening extraction time from 45 to 15 min. In pure water, the dissolution of caffeine and theanine did not change significantly, but total catechin dissolution increased by 0.23 mg/mL and total tea polyphenol dissolution decreased by 3.2 mg/mL. In 76.2% ethanol, the dissolution of caffeine and theanine did not change significantly, but total catechin dissolution increased by 1.57mg/mL and total tea polyphenol dissolution decreased by 1.5 mg/mL. Additionally, we used microwave-assisted technology to further improve the extraction efficiency of green tea, which shortened the extraction time to 2 min. However, the extraction rate remained unchanged. In pure water, the dissolution of caffeine and theanine did not change significantly, but the dissolution of total catechins increased by 0.41 mg/mL and the dissolution of tea polyphenols decreased by 2.9 mg/mL. Ultrasonic treatment increased the proportion of 3-hydroxybutan-2-one, (5S)-5-(hydroxymethyl)oxolan-2-one and 2-phenylethanol, which were the main aroma compounds in tea. Microwave treatment changed the aroma compounds in tea, causing losses in aroma compounds with low boiling point and maintaining (5S)-5-(hydroxymethyl)oxolan-2-one. The taste and aroma of instant green tea improved based on sensory evaluation results.

Subject Areas

ultrasonic wave; microwave; instant green tea; extraction rate; active components; aroma

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