探討大麥芽對乳酸菌發酵黑豆奶抗氧化能力之影響

Abstract

本研究利用Streptococcus thermophilus BCRC 13869與Lactobacillus acidophilus BCRC 10695發酵黑豆奶並添加不同比例 [0.5%及1.0% (w/v)] 之大麥芽，探討乳酸菌在黑豆大麥芽發酵液中之生長情形，並進行黑豆大麥芽發酵液酚類化合物 (總酚、總類黃酮、花青素) 含量變化及抗氧化能力 (DPPH自由基清除能力、亞鐵離子螯合能力、還原力及總抗氧化能力) 之測定。結果顯示添加大麥芽之實驗組與未添加大麥芽之控制組相比，添加 [0.5%及1.0% (w/v)] 大麥芽之實驗組其乳酸菌數經48小時發酵顯著地增加 (p<0.05)，發酵48小時後菌數可達8.41 Log CFU/mL；可滴定酸度顯著地上升 (p<0.05)，顯示添加大麥芽有助於乳酸菌生長。所有組別之總酚、總類黃酮於發酵初期均顯著地增加 (p<0.05)，之後隨著發酵時間增加而遞減，但是添加大麥芽之實驗組比起未添加大麥芽之控制組於發酵終點，仍有較高的總酚、總類黃酮含量。而DPPH自由基清除能力、亞鐵離子螯合能力、還原力及總抗氧化能力之結果顯示，添加大麥芽之組別其抗氧化能力均有顯著地提高 (p<0.05)，其中S. thermophilus BCRC 13869添加1.0% (w/v) 大麥芽發酵黑豆奶可獲得較高的抗氧化能力，顯示大麥芽有助於提升發酵黑豆奶之抗氧化能力。

In this study, black soymilk contained barley malt fermented with Streptococcus thermophilus BCRC 13869 and Lactobacillus acidophilus BCRC 10695 were investigated for the behaviors of starter organisms and the functional components including total phenolic content, total flavonoid content and anthocyanins content during fermentation. The antioxidative activities (DPPH radical-scavenging ability, Fe2+ - chelating ability, reducing power and Trolox equivalent antioxidant capacity) of fermented black soymilk were also examined. The results showed that fermented black soymilk with barley malt significant increased (p<0.05) compared with fermented black soymilk without barley malt on viable count and titratable acidity. Final viable count of fermented black soymilk with barley malt was 8.41 Log CFU/mL after 48 h fermentation. Furthermore, it was found that the content of total phenolic, total flavonoid increased at the initial period of fermentation, then decreased during further fermentation, but fermented black soymilk with barley malt still had higher amounts of phenolic compounds than fermented black soymilk without barley malt after 48 h fermentation. In addition, the antioxidative activities [DPPH radical-scavenging ability, Fe2+ - chelating ability, reducing power and Trolox equivalent antioxidant capacity (TEAC)] of fermented black soymilk with barley malt increased significantly (p<0.05). Black soymilk with barley malt fermented with S. thermophilus BCRC 13869 showed the highest antioxidative activities among other fermented black soymilk. These results revealed that barley malt could enhance the antioxidative activities of fermented black soymilk.