以紅豆開發富含γ-胺基丁酸機能性發酵乳之研究

Development of gamma-aminobutyric acid-enriched functional fermented milk from adzuki beans

宋鴻宜(Hung-Yi Song)

指導教授 ： 游若篍

國立臺灣大學/生物資源暨農學院/食品科技研究所/博士(2017年)

https://doi.org/10.6342/NTU201700611

摘要

γ-胺基丁酸(GABA)是一種廣泛分佈於自然界的非蛋白質胺基酸，為中樞神經系統最主要的神經傳導抑制劑，並具有多種生理功能。天然食物中γ-胺基丁酸含量很低，利用微生物開發富含GABA之機能性食品具消費市場潛力。本研究以產自屏東縣萬丹鄉之高雄8號國產紅豆(Vigna angularis)為原料，評估不同前處理條件對提高紅豆中γ-胺基丁酸含量之影響，進一步以不同益生菌接種於紅豆乳中，篩選最適生產GABA之益生菌株，並調整培養基最適化條件，以開發兼具益生菌及GABA雙重功效之機能性紅豆發酵乳。研究結果顯示，生鮮紅豆中的GABA含量為6.81 mg/100g DW，經37℃下浸泡8小時後，GABA含量增加至90.21 mg/100g DW，比未經處理的紅豆提高13倍，總酚含量由14.85 mg GAE/g DW增加至18.04 mg GAE/g DW，惟浸泡處理不利於花青素穩定作用致花青素含量降低；將紅豆於37℃浸泡8小時後，再經-20℃低溫冷凍48小時再於室溫解凍24小時，GABA含量較浸泡處理後高出70％，花青素含量及總酚含量卻減少47％及51％，顯示浸泡後再經冷凍、解凍提高GABA含量效果有限。將紅豆添加5倍水於37℃浸泡8小時後磨漿，添加5％脫脂奶粉製成紅豆乳，接種Lactobacillus rhamnosus GG發酵36小時，GABA含量從0.05 mg/mL增加到0.44 mg/mL，達到最高值，花青素含量比未發酵前增加2.88倍，總酚含量提高約40％；運用反應曲面法分析接種Lb. rhamnosus GG之紅豆乳最適培養條件，結果顯示紅豆乳基質中添加半乳糖、麩胺酸鈉和吡哆醇均會提高GABA產量，其分別可使GABA產量增加23~38％、24~68％及8~36％。紅豆乳接種Lb. rhamnosus GG生產GABA之最適培養條件為添加半乳糖1.44％，麩胺酸鈉2.27％和吡哆醇0.20％，在最佳培養條件下，發酵紅豆乳中GABA的生成量為1.12 mg/ml，比未發酵前增加了22.4倍，經感官品評試驗，調整發酵紅豆乳糖酸比為16，在甜度、酸度及整體接受度上均具較高的品評分數，製成之紅豆發酵乳於4℃儲存15天GABA含量可維持1.26 mg/mL，乳酸菌數為log 9.42 cfu/ml，產品除可以富含γ-胺基丁酸為訴求外，並兼具菌生菌功效，可作為消費者每日補充GABA的食物來源。

關鍵字

γ-胺基丁酸 ； Lactobacillus rhamnosus GG ； 紅豆 ； 反應曲面法

並列摘要

Gamma-aminobutyric acid (GABA) is a non-protein amino acid widely distributed in nature, and is a major inhibitory neurotransmitter in the central nervous which provides several physiological functions. Development of functional foods rich in GABA through microbial fermentation has a potential in the consumer market. This study was used the domestic adzuki beans(Vigna angularis) variety Kaohsiung No.8 that produced from Wandan Township as the material to evaluate the effect of different pretreatment conditions on the GABA accumulation, and further inoculate different probiotics in the adzuki bean milk to select the suitable probiotic strain for GABA production. This study also adjusts the optimum conditions for the culture media and develops functional fermented adzuki bean milk that carries both the GABA and probiotics. The GABA content in raw adzuki beans was 6.81 mg/100g DW. After soaking at 37℃ for 8 hours, the GABA content in the adzuki beans increased to 90.21 mg/100g DW, which was 13-fold higher than non-treated adzuki beans. The total phenolic acid content was increased from 14.85mg GAE/g DW to 18.04mg GAE/g DW, the soaking treatment was not favorable to stabilization of the anthocyanins that the content of anthocyanins was decreased. The GABA content of adzuki bean freezing at -20℃ for 48 hours and thawing at room temperature for 48 hours after soaking at 37℃ for 8 hours was increased 70% higher than that of un-freezing beans. The anthocyanin and total phenolic content of adzuki beans after freezing and thawing treatment was decreased 47% and 51% respectively, which indicated that the effect of freezing and unfreezing treatment after soaking treatment on raising the content of GABA was limited. The adzuki beans was added 5 folds water and soaked at 37℃ for 8 hours, homogenized into thick liquid and added 5％ skimmed milk powder to make adzuki bean milk. Adzuki bean milk inoculated with Lactobacillus rhamnosus GG increased GABA content from 0.05 mg/mL to 0.44 mg/mL after 36 hours of fermentation, which showed the greatest elevation in this study. The anthocyanin content was increased 2.88-fold and the total phenolic content was increased 40％ than un-fermented adzuki bean milk. Further, the optimal cultural condition to adzuki bean milk inoculated with Lb. rhamnosus GG to improve the GABA content by response surface methodology (RSM). The results showed that GABA content was dependent on the addition of galactose, monosodium glutamate and pyridoxine with which the increasing ratios of GABA was 23~38％, 24~68％, and 8~36%, respectively. The optimal culture condition for GABA production of adzuki bean milk was addition of galactose 1.44%, monosodium glutamate 2.27%, and pyridoxine 0.20%. Under the optimal cultural condition, the GABA content of fermented adzuki bean milk was 1.12 mg/ml, increased 22.4 folds higher than that of the unfermented adzuki bean milk. The acid-sugar ratio of fermented adzuki bean milk was adjusted to 16 by sensory evaluation had higher score on sweetness, acidity and overall acceptance of the fermented adzuki bean milk. After 15 days of storage at 4℃, the GABA content of fermented adzuki bean milk was remained 1.26 mg/ml and the lactic acid bacteria number was maintained at log 9.42 cfu/ml. The fermented adzuki bean milk was contained both in GABA and probiotic that suitble for consumers as a daily supplement as suggested.

並列關鍵字

Gamma-aminobutyric acid (GABA) ； Lactobacillus rhamnosus GG ； adzuki beans ； response surface methodology(RSM)

參考文獻

許雅鈞，2004。雙叉桿菌胞內物對活性氧之抗致突變性與抗氧化性。臺灣大學食品科技研究所碩士學位論文，臺北市。

陳慶源、黃崇真、邱雪惠、廖啟成，2007。乳酸菌之保健功效與產品開發。農業生技產業季刊11，60-68。

陳正敏、李穎宏，2006。紅豆納豆產品加工。高雄區農情月刊105，4-6。

傅以中，2005。從蔬果種子發芽過程中量產高γ-胺基丁酸(GABA)加工新產品的開發及其相關製備技術。行政院農業委員會農糧署94年度科技計畫研究報告。

鄒梅君、梁志弘、何志剛、江文德，2012。紅豆與大豆發芽過程中形成γ-胺基丁酸之研究。臺灣農業化學與食品科學 50(4)，217-226。