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|標題:||Effect of fermentation or its tannase by Aspergillus oryzae NCH 42 on functional properties of Galla rhois|
五倍子經Aspergillus oryzae NCH 42 發酵或其單寧酶處理對其機能性之影響
|摘要:||Galla chinensis (GAC) is a traditional Chinese herb distributed widely in southern China. It is used for the treatment of inflammation, dysentery, toxicosis, sore and so on. GAC is the gall produced by some parasitic aphids (family Pemphigidae) on the Rhus leaves of the family Anacardiaceae ﹝mainly Rhus chinensis Mill, Rhus potaninii Maxim, and Rhus punjabensis var. sinica (Diels) Rehd. et Wils﹞. Tannins (commonly referred to as tannic acid, TA) are water-soluble polyphenols that are present in many plant foods. GAC contains a large amount of gallotannin, a typical kind of hydrolysable tannin, even exceeding 70% of its weight. TA is considered to be a generally regarded as safe (GRAS) food additive, which may be present from 10 to 400 ppm. Tannase (E.C.188.8.131.52) can catalyze the hydrolysis of ester and depside bonds in hydrolysable tannins such as gallotannin, and releases gallic acid and glucose. Gallic acid (GA, 3,4,5-trihydroxybenzoic acid) is a naturally occurring antioxidant and antibacterial agent. Compared with gallotannin, gallic acid has lower cell toxicity and has more applications in agriculture and industry. In this study, an extracellularly tannase-producing fungus strain, Aspergillus oryzae NCH 42, was used.Changes in functional property of GAC after the enzymatic hydrolysis and fermentation by Asp. oryzae NCH 42 were studied. Results showed that, optimal condition for enzymatic hydrolysis of GAC water extract performed at 35 ℃, pH 5.5, shaking rate at 50 rpm and the tannase activity at 400U gave the best result for release of gallic acid and residual tannc acid content. On the other hand, optimal conditions for fermentation of GAC by A. oryzae NCH 42 were as follows: solid to water ratio at 1:30, temperature at 35 ℃, shaking rate at 120 rpm, initial pH at 5.0 and spore concentration of inoculum was 107 spores/ml. The results of antioxidant properties showed that enzymatic hydrolysates prepared by reacting GAC with tannase for 20 minutes (EH-20) had highest antioxidant activities during enzymatic hydrolysis, while antioxidant properfies of fermentation products after the fermentation for 3 days (F-3) were the highest. The F-3 shows better scavenging activity and reducing power than EH-20 did. The EH-0 and F-0 have highest antibacterial properties. All samples showed stronger antimicrobial activity against gram positive bacterial strains. Antibacterial properties of GAC decreased during enzymatic hydrolysis or fermentation. The tyrosinase inhibitory activity of GAC after enzymatic hydrolysis or fermentation decreased ;however, enzymatic hydrolysates had higher inhibitory activity. The GAC after enzymatic hydrolysis or fermentation increased the cell viability of RAW 264.7 cell and Clone 9 cell, but decreased the cell viability of HepG2 cell. The GAC after fermentation or tannase treatment had effects on decresing the generation of NO by RAW 264.7 cells, and lowering the amount of NO produced in the presence of LPS. This indicated that the GAC after enzymatic hydrolysis or fermentation had increased anti-inflammatory activity. In conclusion, cytotoxicity of the GAC extract decreased after fermentation or tannase treatment, and the functionality increased.|
|Appears in Collections:||食品暨應用生物科技學系|
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