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Pressurized liquid extraction of caffeine and catechins from green tea leaves using ethyl lactate, water and ethyl lactate + water mixtures

Paper ID Volume ID Publish Year Pages File Format Full-Text
18826 43035 2015 7 PDF Available
Title
Pressurized liquid extraction of caffeine and catechins from green tea leaves using ethyl lactate, water and ethyl lactate + water mixtures
Abstract

•Ethyl lactate, water and their mixtures were studied for decaffeinating green tea.•Solubility of caffeine in pure and mixed solvents was studied at 298 K.•Pressurized liquid extraction was accomplished comparing the different solvents.•The solubility in the mixed solvents was considerably higher than in pure solvents.•Extracts with higher caffeine/catechins selectivity were obtained with ethyl lactate.

Ethyl-lactate (ethyl 2-hydroxy-propanoate) is a bio-renewable agrochemical solvent, very suitable and environmental benign for food applications, permitted by the U.S. Food and Drug Administration as pharmaceutical and food additive. In previous work, the authors demonstrated that pressurized liquid extraction (PLE) using ethyl lactate is a suitable alternative to remove caffeine from vegetal materials, e.g. green coffee beans and green tea leaves. The solubility of caffeine in ethyl lactate + water mixtures, at ambient temperature and pressure, exhibits a substantial increase for 60:40% ethyl lactate + water mixtures (data reported in this work). This result motivated the analysis of the effect of the ethyl lactate + water mixtures for the decaffeination target.Furthermore, in the case of green tea, the removal of caffeine reducing the extraction of catechins is desirable due to the adverse effects of caffeine on health, while catechins are high valued functional food ingredients. Thus, the use of ethyl lactate, water and ethyl lactate + water mixtures to attain this objective, i.e. the removal of caffeine form green tea leaves minimizing the extraction of catechins, was studied in this work.PLE was carried out in the temperature range 373–473 K and using different ethyl lactate + water mixtures. Extraction yield and recovery of key bioactive compounds (caffeine and monomeric catechins) were determined and compared, and the caffeine/catechins selectivity of the different solvents employed was estimated.High extraction yields were obtained with a mixture containing 25:75% of ethyl lactate + water, with values around 1.5 and 3.5 times higher than, respectively, the yields obtained with water and ethyl lactate. Yet, pure ethyl lactate proved to be the most selective solvent to extract caffeine from green tea leaves, minimizing the co-extraction of catechins, with a caffeine/catechins selectivity of 2.8 to 5.5 in the range 373–423 K. At these temperatures, with short extraction times (20 min) the recovery of caffeine is in the range 53–76% but only 26–36% of catechins present in the tea leaves were removed.

Keywords
Green tea; Caffeine; Catechins; Ethyl lactate; Pressurized liquid extraction; Solubility
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Pressurized liquid extraction of caffeine and catechins from green tea leaves using ethyl lactate, water and ethyl lactate + water mixtures
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Publisher
Database: Elsevier - ScienceDirect
Journal: Food and Bioproducts Processing - Volume 96, October 2015, Pages 106–112
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us