发酵葡萄酒之特性探讨

发酵葡萄酒之特性探讨 發酵葡萄酒之特性探討 Study on Characteristics of Grape Wine 研究生: 蔡承芸 指導教授:謝寶全 [摘要] 本研究利用土壤中篩選出的麴菌產生之單寧酶來降低葡萄酒中的澀味,再由發酵率較佳之 Saccharomyces sp.來釀製葡萄酒,並且探討菌種產生單寧酶之最適培養條件及最適活性。在發酵期 間測定可溶性固形物、還原糖、總糖、酒精度、總酸、pH值、總色素、抗氧化力及單寧酸含量之 變化。由結果中顯示,Saccharomyces sp. Y12在含有蔗糖20%,酵母抽出物 0.6%,氯化銨0.6%, 磷酸二氫鉀0.2%,硫酸鎂0.1%,pH 5.5之最適培養基中,於30?,培養4天後,其發酵率可達 51.8%左右。從土壤中分離篩選出有效之單寧酸分解菌株,經鑑定為Aspergillus niger,此菌株在含 有單寧酸4%,蔗糖2%,酵母抽出物0.2%和氯化銨0.2%,硫酸鎂0.1%,pH 5.0之最適培養基中, 於30?,振盪(120rpm)培養4天後,其單寧酶之活性可達55 U/100mL左右,菌體乾重為0.77g/mL。 而其對單寧酸濃度之耐性可達20%,對偏亞硫酸鉀(K2S2O5)濃度之耐性可達200ppm,但是隨著酒 精濃度的增加會抑制麴菌的生長,且當培養基中沒食子酸濃度為2%時,其對單寧酶的抑制率可達 到100%。接種Aspergillus niger之葡萄酒其單寧酸含量較不接種之葡萄酒低,但其抗氧化能力反而 提高。而無論接種麴菌與否,自製葡萄酒之單寧酸含量均較市售之葡萄酒為低,且其抗氧化能力亦 不及市售之葡萄酒。在毒性試驗方面,無論是Aspergillus niger之培養液或是經Aspergillus niger 發酵之葡萄汁,在0.1~0.5mg/plate的添加濃度範圍內,均不具有毒性及致突變性,且培養液及葡 萄汁分別可抑制82.3%和55.6% B[a]P所引起之致突變性,而且可抑制44.6%和29.6% NQNO引起 之致突變性。 關鍵字: 葡萄酒、澀味、單寧、單寧酶 【Abstract】 The purposes of present study were to brew wine by screening Saccharomyces sp. and isolating Aspergillus sp. to reduce the astringency taste in wine. Then, investigate parametric optimization of extracellular tannase from Aspergillus sp. Parameters observation during fermentation were the change of oBrix value, residual sugar, total sugar, pH value, alcohol content, total acid, total pigment, antioxidant activity and tannic acid. Results showed that Saccharomyces sp. Y12 cultivated in optimum medium containing sucrose 20%, yeast extract 0.6%, NH4Cl 0.6%, KH2PO4 0.2%, MgSO4 7H2O 0.1%, pH5.5, the fermentation yield were 51.8% at 30? for 4 days. The strain No. 3 having the ability to hydrolysis tannins isolated from the soil.It was identified as Aspergillus niger. The strain cultivated in optimum medium containing tannic acid 4%, sucrose 2%, yeast extract 0.2%, NH4Cl 0.2%, MgSO4 7H2O 0.1%, pH5, the tannase activity and dry mycelium weight were 55 U/100mL, and 0.77g/mL under the cultivation conditions(30?,120rpm) for 4 days. The gallotannin tolerance limits for Aspergillus niger was 20%. The potassium metabisulfite (K2S2O5) tolerance limits for Aspergillus niger was 200ppm. However, mold growth was inhibited by increasing concentrations of alcohol. Gallic acid inhibition indicates end-product repression of the enzyme for 100% inhibition when gallic acid concentration was 2%. The wine that inoculated Aspergillus niger had lower tannic acid content than blank non-inoculation Aspergillus niger, but antioxidant activity was increased for the former. However, inoculated Aspergillus niger or not that has less tannic acid content and antioxidant activity than commercial product. In Ames test, no toxicity and mutagenicity were found in culture medium or grape juice by Aspergillus niger at the dosage of 0.1~0.5mg/plate. The inhibitory effect of culture medium and grape juice by Aspergillus niger to indirect mutagens of brnzo[a]pyrene (B[a]P) were 82.3% and 55.6%, respectively; whereas the inhibitory effect of culture medium and grape juice by Aspergillus niger to mutagenicity of 4-nitroquinoline-N-oxide(NQNO) were 44. 6% and 29.6%, respectively. Keywords: Grape wine Astringency Tannin Tann