African Journal of
Food Science

  • Abbreviation: Afr. J. Food Sci.
  • Language: English
  • ISSN: 1996-0794
  • DOI: 10.5897/AJFS
  • Start Year: 2007
  • Published Articles: 904

Full Length Research Paper

Increasing gallic acid contents in green tea extracts using acid hydrolysis

Hae-Soo Kim
  • Hae-Soo Kim
  • Department of Food Science and Technology, Chonnam National University, Gwangju 61186, Republic of Korea.
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Do Yeon Jeon
  • Do Yeon Jeon
  • Department of Food Science and Technology, Chonnam National University, Gwangju 61186, Republic of Korea.
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Ha-Nul Lee
  • Ha-Nul Lee
  • Department of Food Science and Technology, Chonnam National University, Gwangju 61186, Republic of Korea.
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Seong-Jin Hong
  • Seong-Jin Hong
  • Department of Food Science and Technology, Chonnam National University, Gwangju 61186, Republic of Korea.
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Seung-Hee Nam
  • Seung-Hee Nam
  • Institute of Agricultural Science and Technology, Chonnam National University, Gwangju 61186, Republic of Korea.
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Jeong Choi
  • Jeong Choi
  • Jeonnam Agricultural Research and Extension Services, Naju-si 58213, Republic of Korea.
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Yong-Hee Kwon
  • Yong-Hee Kwon
  • Research Institute of Climate Change and Agriculture, Rural Development Administration, Jeju 690150, Republic of Korea.
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Doo-Gyung Moon
  • Doo-Gyung Moon
  • Research Institute of Climate Change and Agriculture, Rural Development Administration, Jeju 690150, Republic of Korea.
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Young-Min Kim
  • Young-Min Kim
  • Department of Food Science and Technology, Chonnam National University, Gwangju 61186, Republic of Korea.
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  •  Received: 17 September 2020
  •  Accepted: 04 January 2021
  •  Published: 31 March 2021

Abstract

Gallic acid (GA) is a functional ingredient abundant in Chinese pu-erh tea. The aim of this study was to increase the GA content in green tea extracts using acid hydrolysis. (-)-Epigallocatechin gallate treated with 1 M hydrochloric acid at 110°C for 1 h resulted in a GA yield of 45.6%. However, under these conditions, (-)-epigallocatechin was easily oxidized and rendered undetectable. On applying the same treatment to green tea extracts of Korea-cultivated Chamnok, a native species, and Yabukita, the GA contents increased from 0.17 to 4.87, 0.28 to 5.33 and 0.17 to 4.44 mM, respectively. In Chamnok extracts prepared following harvesting at three different time points, the GA contents increased from 0.17 to 4.48, 0.12 to 5.16 and 0.06 to 5.71 mM. Therefore, it is possible to produce green tea extracts with high GA concentrations using simple acid hydrolysis. This will greatly benefit the production of functional ingredients and will be useful in the beverage industry.

 

Key words: Domestic cultivar, EGCG, EGC, tannase.

Abbreviation

EC, (-)-epicatechin; ECG, (-)-epicatechin gallate; EGC, (-) -epigallocatechin; EGCG, (-)-epigallocatechin gallate; GA, gallic acid.