Fermentation and complex enzyme hydrolysis for improving the total soluble phenolic contents, flavonoid aglycones contents and bio-activities of guava leaves tea

[Display omitted] •Fermentation and enzymes hydrolysis (FE) increased total phenolic content of GLT.•Soluble and insoluble-bound forms of phenolics were analyzed by HPLC.•FE processing gave the greatest yields of quercetin and kaempferol from GLT.•FE processing upgraded the antioxidant and α-glucosi...

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Published in:Food chemistry Vol. 264; pp. 189 - 198
Main Authors: Wang, Lu, Luo, You, Wu, Yanan, Liu, Yan, Wu, Zhenqiang
Format: Journal Article
Language:English
Published: England Elsevier Ltd 30.10.2018
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ISSN:0308-8146, 1873-7072, 1873-7072
Online Access:Get full text
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Summary:[Display omitted] •Fermentation and enzymes hydrolysis (FE) increased total phenolic content of GLT.•Soluble and insoluble-bound forms of phenolics were analyzed by HPLC.•FE processing gave the greatest yields of quercetin and kaempferol from GLT.•FE processing upgraded the antioxidant and α-glucosidase inhibition activity of GLT. There are both soluble and insoluble-bound forms of phenolics in tea-leaf products. In order to increase total soluble phenolics contents, guava leaves tea (GLT) was first fermented with Monascus anka and Saccharomyces cerevisiae, and then hydrolyzed with complex enzymes. The changes in phenolics profiles, antioxidant activities and inhibitory effect on α-glucosidase in processed GLT were investigated. Compared with the un-fermented GLT, fermentation and complex enzymatic processing (FE) significantly increased the total phenolics, total flavonoids, quercetin and kaempferol contents by 2.1, 2.0, 13.0 and 6.8 times, respectively. After the FE, a major proportion of phenolics existed in the soluble form. Quercetin was released in the highest amount among different phenolics. In addition, soluble phenolic extracts from GLT following FE exhibited a highest antioxidant activity and inhibitory effect on α-glucosidase. The paper suggested an improved method for processing GLT into high-value products rich in phenolics and flavonoids aglycones with enhanced health benefits.
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ISSN:0308-8146
1873-7072
1873-7072
DOI:10.1016/j.foodchem.2018.05.035