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  • 學位論文

抗壞血酸與兒茶素在酒精飲料中褐變之研究

Browning of Alcoholic Beverages Containing Ascorbic Acid and Catechin

指導教授 : 吳瑞碧

摘要


非酵素性褐變經常發生於酒品儲藏期間並使其品質降低。因此許多製酒業者經常使用抗壞血酸在水果釀造酒中作為抗氧化劑,以維持顏色穩定。然而,卻有學者指出於酒類中添加抗壞血酸可能有促進褐變的現象。本研究即以還原市售白葡萄酒作為真實系統代表,探討抗壞血酸在市售水果釀造酒中對褐變的影響,此外也改變儲藏條件以釐清環境因子對於抗壞血酸影響褐變的情形。 結果顯示,當市售水果釀造酒中兒茶素含量低時,添加抗壞血酸不會產生促進褐變的現象。避光缺氧儲藏環境中,抗壞血酸在酒精溶液中主要降解途徑為有氧降解。終產物包括 2-furoic acid (2-FA) 及 3-hydroxy-2-pyrone (3OH2P),其總量隨著酒精濃度增加而增加,但酒精溶液之褐變情形卻隨酒精濃度提升而降低。根據結果推測,上述抗壞血酸降解終產物在酒精溶液中應該不是造成褐變的主因,可能是抗壞血酸降解途徑的中間產物 L-xylosone 與兒茶素作用並產生褐變之物質所導致。缺氧儲藏期間,抗壞血酸與兒茶素降解及褐變程度皆顯著地大幅降低,且儲藏期間皆未測得抗壞血酸降解產物 2-FA 及 3OH2P,其原因推測為抗壞血酸與兒茶素降解後仍停留在降解途徑過程中的中間產物,並未形成最後造成褐變的物質,因而降低褐變現象。照光儲藏條件下,抗壞血酸、兒茶素與抗壞血酸降解產物皆快速產生降解。為此推測,在光線的作用下會促進抗壞血酸與兒茶素降解,同時加速二者作用形成分子量更大的產物,進而使酒精性飲料褐變顯著提升。 綜合以上結果,建議添加抗壞血酸到酒品中做為抗氧化劑前應先了解酒品中兒茶素的含量,並考慮是否有其添加的必要性。選擇具有遮光效果的容器,避免與光線接觸,同時也應與氧氣隔絕,如此即可避免於儲藏過程中發生褐變之現象。

並列摘要


Non-enzymatic browning commonly occurs during wine storage and downgrade the quality. In order to improve color quality of fruit fermented liquor, ascorbic acid is usually used as an antioxidant in wine industry. On the contrary, some researchers reported that the addition of ascorbic acid may increase browning in wine. In the present study, we used reconstituted white wine as real alcoholic beverages to evaluate the effect of ascorbic acid induce on browning in fruit fermented liquors. Furthermore, the storage test in various conditions was conducted for understanding the effect of ascorbic acid on wine browning. The results shown that the addition of ascorbic acid does not increase browning in wines contain low catechin content. The ascorbic acid was found to undergo aerobic degradation in alcoholic solution during dark storage. The final aerobic degradation products of ascorbic acid include 2-furoic acid (2-FA) and 3-hydroxy-2-pyrone (3OH2P). The production of 2-FA and 3OH2P increase with the increase of alcoholic concentration, whereas, the browning of alcoholic solution decrease with the increase in alcoholic concentration. According to the above result, we postulate that ascorbic acid degradation end products shouldn’t be the major factor to cause browning in alcoholic beverages. L-xylosone, the medial product of ascorbic acid degradation, was considered to interact with catechin and form browning pigments. The degradation of ascorbic acid and catechin, and browning index were significantly decreased in alcoholic solutions during anaerobic storage. However, none ascorbic acid degradation products were detected including 2-FA and 3OH2P during anaerobic storage. We postulate that after ascorbic acid and catechin degraded, they still stay in the medial of pathway, cause the final browning pigment substance wasn’t formed and decreases the browning index. The amounts of ascorbic acid, catechin and ascorbic acid degradation products drop rapidly in alcoholic solution during storage under light exposed. We postulate that light promotes the degradation of ascorbic acid and catechin, accelerates the interaction between those products to form high molecular weight aggregates, and significantly accelerate the browning in alcoholic beverages. The above-mentioned results suggest that the content of catechin should be considered before added ascorbic acid into wine for its preventive/ antioxidant advantages. After bottling, the wine/ liquor products should choose the dark containers to keep away from exposure to light and oxygen, thus prevent the browning during storage.

參考文獻


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