小麥草汁添加對利用醋酸菌及酵母混合菌種發酵紅茶湯之影響

小麥草為禾本科小麥之初生莖葉，含豐富的營養成分及良好的抗氧化活性，而添加有蔗糖之紅茶湯液經接種由酵母菌及醋酸菌所組成之菌酛後所得之發酵液亦被證實具有提高動物體內抗氧化力的功效。本研究以混合有小麥草汁之含糖紅茶湯液為發酵基質，接種主由酵母菌（Dekkera bruxellensis）和醋酸菌（Gluconacetobacter rhaeticus及Gluconobacter roseus）所組成之菌酛，接種量為20% (v/v)，次於29 ± 1℃下靜置培養12天。探討小麥草汁添加比例對發酵液中酵母菌及醋酸菌菌數、pH、醣類、有機酸及水溶性維生素含量之影響。結果顯示，隨著發酵時間增加，pH由起始4.0逐漸下降至約2.9。各組酵母菌及醋酸菌分別於發酵至第六天及第三天達最大菌量，分別為7.2 log (cfu/mL) 及5.1 log (cfu/mL)。以混合菌酛發酵後之含小麥草紅茶其有機酸（醋酸、葡萄糖酸及酒石酸）及水溶性維生素（B1、B2及泛酸）含量皆較未發酵前提升，維生素B1、B2及泛酸於發酵至第12天其含量分別約為31.15~76.45 mg/100mL、44.71~76.10 mg/100mL及5.97~15.88 mg/100mL。以培養基質比例為小麥草汁：紅茶 = 1：1 (v/v) 之混合比例（初始蔗糖含量約4%, w/v），經發酵六天所得之小麥草汁紅茶較未發酵前不僅顯著提升代謝產物如有機酸及水溶性維生素等含量。整體而言，小麥草汁強化的紅茶經發酵後可獲得較多的營養成分。

關鍵字

小麥草；紅茶；有機酸；水溶性維生素；醋酸菌；酵母菌

並列摘要

Wheatgrass, the mature sprout of wheat seeds, is rich in nutrient components and antioxidant activity. Meanwhile, fermentation of the sugared black tea decoction with a symbiotic culture of yeast and acetic acid bacteria has also been proved to improve its nutrition and the in vivo antioxidant activity. In this study, a sugared black tea decoction supplemented with wheatgrass juice was used as a fermentation substrate. A starter comprising of yeast (Dekkera bruxellensis) and acetic acid bacteria (Gluconacetobacter rhaeticus and Gluconobacter roseus) was inoculated at 20% (v/v), and fermented statically at 29 ± 1oC for 12 days. Effects of ratios of wheatgrass juice to black tea on viable cell counts, pH, contents of organic acids, and water soluble vitamins during fermentation were investigated. The results showed that the pH values decreased gradually from 4.0 to 2.9 with time. Viable counts of yeast and acetic acid bacteria reached their maximum values 7.2 log cfu/mL at Day 6, and 5.1 log cfu/mL at Day 3, respectively. All fermented products were characterized as having increased amounts of organic acids (acetic acid, gluconic acid, and tartaric acid) and water-soluble vitamins (B1, B2, and pantothenic acid), but decrease in sugar contents after 12 days of fermentation. Contents of vitamins B1, B2, and pantothenic acid are 31.15-76.45 mg/100mL, 44.71-76.10 mg/100mL, and 5.97-15.88 mg/100mL, respectively. Consequently, fermentation of a wheatgrass juice supplemented black tea at ratio of 1 : 1 (v/v) (contains ca. 4% sucrose, w/v) for 6 days not only resulted in significant increase of organic acids and water soluble vitamins, but also had mild taste and better palatability. Our results suggest that intake of fermented black tea enhanced with wheatgrass juice is advantageous over unfermented one in terms of its nutritive values.

並列關鍵字

Wheatgrass juice ； Black tea ； Organic acids ； Water-soluble vitamins ； Gluconacetobacter rhaeticus ； Gluconobacter roseus ； Dekkera bruxellensis

國際替代計量

小麥草汁添加對利用醋酸菌及酵母混合菌種發酵紅茶湯之影響

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