加熱溫度及酵母菌生物轉換對苦瓜皂苷之影響

Abstract

苦瓜中的苦瓜皂苷為一群具有生理功能性與苦味的三萜類糖苷分子。先期試驗以山苦瓜粉為原料取代啤酒花進行啤酒釀造，發現發酵後山苦瓜啤酒的苦味消失。本研究假設熱加工與酵母菌轉換是影響苦瓜皂苷之可能因子。為了瞭解酒類加工過程中此類糖苷分子的轉換，本文使用花蓮3號山苦瓜進行苦瓜皂苷萃取，以液相層析串連電灑式質譜UPLC-ESI-MS/MS分析苦瓜皂苷，建立7 種苦瓜皂苷(Momordicoside L、3,7,25-trihydroxycucurbita- 5,23(E)-dien-19-al、Momordicoside K、Momordicine I、Momordicoside I、Momordicoside F2、Momordicoside F1)的定性/定量分析平台，後續再分別探討不同加熱溫度以及酵母菌對苦瓜皂苷的影響。熱穩定性實驗結果顯示：以121 ℃高溫高壓處理後，苦瓜皂苷元3,7,25-trihydroxycucurbita- 5,23(E)-dien-19-al和苦味皂苷momordicoside L顯著受到破壞。在100 ℃, 10 min的加熱條件下，功效成分3,7,25-trihydroxycucurbita- 5,23(E)-dien-19-al和苦味皂苷元momordicine I即有明顯的熱降解。除了上述2種苦瓜皂苷元，其餘5種苦瓜皂苷含量在100 ℃, 20 min的加熱條件下並無變化。以酵母菌轉換結果發現：野生型酵母菌可以降低苦味皂苷momordicine I以及momordicoside K的含量，但momordicoside L卻不被酵母菌轉換。綜合結果顯示特定的苦瓜皂苷同時受到熱與酵母菌的影響。

Saponins from Momordica charantia L. are a class of triterpenoid glucoside molecules which attribute to the bitter flavour and possess the pharmacological properties. In an initial trial, we replaced the hops with wild bitter gourd for beer brewing, and found that the bitter taste disappeared after the yeast fermentation. This study assumes that thermal processing and yeast bioconversion are important factors affecting bitter gourd saponins' structural variety, especially for saccharide chains. To find out the conversion of glycoside molecules during alcohol processing, we establish a qualitative and quantitative LC-MS/MS platform by used Hualien No.3 wild bitter gourd. A total of seven saponins containing Momordicoside L, 3,7,25-trihydroxycucurbita- 5,23(E)-dien-19-al, Momordicoside K, Momordicine I, Momordicoside I, Momordicoside F2 and Momordicoside F1 were monitored for evaluating the effects of heating temperature and yeast on saponin structure.The results showed that: 3,7,25-trihydroxycucurbita-5, 23 (E) -dien-19-al and momordicoside L were significantly damaged at 121 ℃. 3,7,25-trihydroxycucurbita-5, 23 (E) -dien-19-al and momordicine I have significant decreased when treated with 100 ℃ for 10 min, while the other saponins did not changed. Momordicine I and momordicoside K were converted by saccharomyces cerevisiae, but momordicoside L did not change. To sum up, specific bitter gourd saponins are affected by heat and yeast.