| Summary: | 碩士 === 朝陽科技大學 === 應用化學系碩士班 === 97 === Polygonum cuspidatum Sied. et Zucc. is a good source of resveratrol in the common traditional Chinese medicine. Resveratrol is also the major component of antioxidation ability in red wine. In this study, the effects of P. cuspidatum in re-fermentation of grape were investigated. The present study was designed to explore the antioxidant potential (by DPPH and reducing power assays), alcohol content, bioactive constituents, antibacterial activity, tyrosinase inhibition activity as well as sensory evaluation after P. cuspidatum was added into the grape re-fermentation process. Among the samples, P. cuspidatum addition group exhibited high inhibition of 77.04 ± 1.02% in DPPH, and 0.12 ± 0.01 mg/mL Vit-C equivalent in reducing power assay under experimental conditions. In contrast, the scavenging activity of control group (without adding P. cuspidatum) had only about 32.86 ± 0.61% in DPPH assay. The total phenolic content did not change significantly during the course of studied, yet the P. cuspidatum groups were still higher than the control group. Furthermore, the alcohol content of both P. cuspidatum and control groups were about 5 to 5.4% after 21 days fermentation. Accordingly, the highest resveratrol levels were 37.44 ± 1.45 and 34.16 ± 1.70 mg/L, determined from CE analysis, for P. cuspidatum and control group respectively, after 21 days of fermentation and diminished afterward. The P. cuspidatum group also exhibited a significantly antibacterial activity against E. coli, S. choleraesuis, and B. subtilis. The tyrosinase inhibition activity, on the other hand, for P. cuspidatum group was 64.34 ± 4.40%, compared to the control group of 55.12 ± 4.29%. This preliminary study indicates the addition of P. cuspidatum in grape re-fermentation could actually improved the overall performance on the anti-oxidation ability, antibacterial activity, and the tyrosinase inhibition activity. In sensory evaluation, addition of P. cuspidatum had the better color and odor response, but more acidic aftertaste, and inadequate sweet taste. In summary, the better overall preference was found in the sample without P. cuspidatum. It seemed that this was affected by the samples with P. cuspidatum has noticeable perception of odor problems and needs to be overcome.
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