本研究利用能產生香氣的Galactomyces geotrichum改善諾麗果汁的風味，並嘗試修飾培養基成份以提高發酵苯乙醇(2-phenylethanol, 2-PE)香氣之產量。依據對諾麗果汁耐性強度以及苯乙醇產量篩選適用菌株，結果獲得Gal. geotrichum w-5。此菌株經馴化後可生長於32.5%小諾麗果汁及40%大諾麗果汁中，並能降解約30%丁酸以及95%以上二甲基丁酸含量，顯著的減少了諾麗果汁的不良氣味，而在發酵後的果汁中均可測得2-PE之香氣成分。在修飾培養基部分，利用Plackett-Burman試驗設計探討苯甲酸、蔗糖、白菜汁、NaCl、Peptone、Tryptone及Tyrosin等七個因子，對2-PE生產之影響。結果得知關鍵因子有Tryptone及NaCl。接著以此二因子進行全因子試驗設計探討各因子主效應，結果NaCl對2-PE生產效果不顯著，因此後續僅探討Tryptone及NaCl之單因子最佳濃度。結果顯示於PDB中添加2.25% Tryptone及1.0% NaCl之修飾培養基經由此菌培養後2-PE含量為33.23 ± 0.14 μg/mL相較於傳統PDB培養基增加21.26倍。綜合上述Gal. geotrichum w-5可有效改善諾麗果汁風味且經由修飾PDB可增加2-PE產量，未來或可添加適當的氮源以提高發酵諾麗果汁的香氣。 The objective of this research is to improve the odor of noni juice by Galactomyces geotrichum fermentation, and to increase the 2-phenylethanol (2-PE) production by modifying fermentation media. A Gal. geotrichum w-5 strain was selected according to noni juice tolerance and 2-PE productivity. This strain can tolerate 32.5% small noni fruit juice and 40% large noni fruit juice, and was able to degrade 30% butyric acid and 95% 2-methylbutyric acid. The unpleasant scent of fermented noni juice was significantly reduced and the 2-PE was detected in fermented noni juice. Improvement of 2-PE fermentation, a Plackett-Burman experimental design of seven factors was used to decide the main ingredients for 2-PE production. The result revealed tryptone and NaCl was significant effective ingredients. Then, a 22 full factorial experimental design for assessment of ingredients effects, the data showed that NaCl was not a significant ingredient for 2-PE production. Furthermore, optimal concentrations of tryptone and NaCl were determined as 2.25% tryptone and 1.0% NaCl, respectively. The production of 2-PE was 33.23 ± 0.14 μg/mL, approximately 21.26 folds higher than that in conventional Potato Dextrose Broth. The medium study has showed that to augment the aroma of fermented noni juice by adding more nitrogenous source is feasible.
