植物乳桿菌發酵蕎麥萃取水之生物活性探討

Bioactivities of buckwheat water-extract fermented by Lactobacillus plantarum BCRC 10069

陳氏碧(TRAN THI BICH)

指導教授 ： 張耀南

國立虎尾科技大學/文理學院/生物科技系碩士班/碩士(2016年)

摘要

本研究將市售帶殼蕎麥種子以50倍超純水進行萃取，並將此水萃取物做為植物乳桿菌(Lactobacillus plantarum BCRC10069)的基本培養基質。首先探討發酵時間、蕎麥殼含量(無殼、1:30 和1:15之殼/水比例)及起始接菌量(1%、5% v/v)與蔗糖添加濃度(0, 5, 10, 20 g/L)對植物乳桿菌的生菌數(viable cell counts; VCCs)與培養基pH值變化的影響。在蕎麥殼含量方面，植物乳桿菌生菌數隨著發酵時間增加而增加，當發酵時間在第12小時增加到將近最高定值， 對5%v/v起始接菌量及10 g/L蔗糖添加之無殼及1:30 和 1:15 (w/w)殼/水比例而言，其植物乳桿菌生菌數分別相對為7.80、8.08 與 8.13 log10 CFU/mL。對1%與5%起始接菌量而言，在不同蔗糖濃度添加下，發酵至第6小時其生菌數分別相對為7.47~7.56 log10 CFU/mL與7.99~8.01 log10 CFU/mL。從此可知，5%起始接菌量較1%起始接菌量有利於植物乳桿菌的生長及生長速率，在5%接菌量與0, 5, 10, 20 g/L不同蔗糖添加濃度探討下，發酵至12小時的植物乳桿菌生菌數分別相對為8.09, 8.08, 8.08, 8.07 log10 CFU/mL，而且培養基 pH大約由起始6.10下降至5.00，不同蔗糖添加濃度似乎對植物乳桿菌的生長菌數及培養基pH的影響無顯著性。因此，本研究將以1:30 殼/水比例、2% 蕎麥粉、5%起始接菌量及無蔗糖添加條件下，進行植物乳桿菌發酵蕎麥水萃取物之上清液之抗氧化活性(DPPH清除率(%)、總酚含量(defined as gallic acid equivalent; GAE)與還原力(defined as vitamin C equivalent, Vit.CE))探討。發酵蕎麥水萃取物上清液的DPPH清除效果隨著發酵時間而略微增加(從起始75.80%增加至80.45%)，然而總酚含量與還原能力則隨著發酵時間而下降(其分別相對由起始0.0974 mg GAE/mL下降至0.0722 mg GAE/mL與由起始0.152 mg Vit.CE/mL下降至0.098 mg Vit.CE/mL)。然而，發酵過BW水萃取物較未發酵BW者具有高抗氧化活性，因此，發酵過BW水萃取物具有促進LAB生長和抗氧化能力可作為益生菌飲料來幫助改善消費者的健康和營養。

關鍵字

植物乳桿菌 ； 蕎麥水萃取物 ； 發酵時間 ； 生菌數 ； 抗氧化活性

並列摘要

In this study, the water-extract from 2% (w/v) flour of common BW (Fagopyrum esculentum Moench) (BW) was used to be the culture medium for the growth of Lactobacillus plantarum BCRC 10069 and the antioxidant ability of fermented extract was investigated. Firstly, the effects of fermentation time, BW hull content, starter concentration (1%, 5% (v/v)) and sucrose addition (0, 5, 10, 20 g/L) on the cell viability of L. plantarum, and the pH of the extract medium were investigated. For BW hull content (without hull, 1:30 and 1:15 in w/w of hull/water), the cell viabilty (defined as viable cell counts; VCCs) of L. plantarum increased up to certain values with increasing the first 12-hour (h) fermentation time. The VCCs for without hull, 1:30 and 1:15 (w/w) hull contents with 5% starter and 10 g sucrose/L at the 12th hr fermentation were 7.80, 8.08 and 8.13 log10 CFU/mL, respectively. For 1% and 5% starters with 0, 5, 10, 20 g/L sucrose additions, the VCCs obtained at the 6th h fermentation were around 7.47~7.56 log10 CFU/mL and 7.99~8.01 log10 CFU/mL, respectively. It was found that the growth rate of L. plantarum for 5% starter was higher than that for 1% one. The VCCs obtained at the 12th h fermentation for 0, 5, 10, 20g/L sucrose additions with 5% starter were 8.09, 8.08, 8.08, 8.07 log10 CFU/mL respectively, with pH values ranging around from 6.10 to 5.00. There was no significant effect of sucrose addition concentration on VCCs of L. plantarum and mediun pH of BW water-extract for each starter concentration. This study demonstrated the fermented BW water-extract deriving from hull/water at ratio 1:30 (w/w), flour/water 2% w/w, inoculum 5% and no sugar is a prospect media for the growth of L. plantarum BCRC 10069 and its antioxidant capacity (DPPH scavenging activity (defined as %), total phenolic contents (TPC defined as gallic acid equivalent; GAE) and reducing power (RP defined as vitamin C equivalent, Vit.CE) were determined. The DPPH scavenging activity of fermented BW water-extract was from 75.80% at the 0th h to 80.45% at the 12th h and was slightly increased with fermtation time, while TPC from 0.0974 mg GAE/mL at the 0th h to 0.0722 mg GAE/mL at the 12th h and RP from 0.152 mg Vit.C/mL at the 0th h to 0.098 mg Vit.C/mL at the 12th h decreased with fermentation time. However, the antioxidant activities of the fermented BW water-extracts in this work were higher than those of the unfermented BW ones. These results suggested that the fermented BW water-extract improved the growth of LAB with antioxidant capacity could provide a probiotic beverage to contribute to the health and nutritional improvement of consumers.

並列關鍵字

Lactobacillus plantarum ； BW water-extract ； Fermentation time ； viable cell counts ； antioxidant activity

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