台灣黏質發酵乳之機能性研究

Abstract

台灣黏質發酵乳 (Taiwanese ropy fermented milk, TRFM) 由本研究室保存，含有可分泌胞外多醣體 (exopolysaccharide, EPS) 之乳酸菌，其質地黏稠類似芬蘭傳統發酵乳viili，因此TRFM又稱作Taiwanese viili。本研究室過去以聚合酶連鎖反應－變性梯度膠體電泳 (polymerase chain reaction-denaturing gradient gel electrophoresis, PCR-DGGE) 配合16s rDNA定序方法鑑定TRFM中四株乳酸菌 (Lactococcus lactis subsp. cremoris TL1, TL3, TL4 and Leuconostoc mesenteroides TL2) 及三株酵母菌 (Kluyveromyces marxianus TY1, Pichia fermentans TY2 and Saccharomyces unisporus TY3)。本研究之目的為進一步評估TRFM及其分離菌株之機能性，包括抗氧化、美容功能、抑制血管緊縮素轉化酶 (angiotensin-converting enzyme, ACE) 及免疫調節機能評估。 為了解TRFM之抗氧化能力，試驗中檢測亞鐵離子、銅離子的螯合能力及DPPH自由基的清除力。TRFM上清液之DPPH清除力隨著發酵時間增加，但其亞鐵離子和銅離子的螯合力與對照組沒有顯著差異。在美容功能部分，TRFM上清液對於黑色素催化酵素酪胺酸酶的抑制力低於50%，且與兩種痤瘡病原菌共培養均沒有抑菌效果。ACE為人體調控血壓之重要酵素，在臨床治療上，抑制ACE的活性可治療高血壓。本試驗檢測TRFM上清液對ACE的抑制效果，發現隨著發酵時間增長，其ACE抑制力越高。 至於免疫調節的部分，胞外試驗的結果顯示TRFM及其分離菌株可刺激小鼠巨噬細胞株RAW 264.7和小鼠脾臟細胞分泌促發炎反應細胞激素、TH1細胞激素和多效性細胞激素IL-10，表示TRFM具有免疫調控之潛力。將TRFM及菌株餵予致敏小鼠，可抑制總IgE及過敏原特異IgE在血清中的濃度，且不同菌株改善過敏的途徑不同；餵予致結腸炎小鼠，則可改善糞便出血評分，結腸長度顯著增加。 由以上結果可得知TRFM及分離菌株具有不同面向之機能性。除了在過敏及結腸炎的動物模式中有顯著的改善效果，其抗氧化和ACE的抑制能力仍未經動物試驗證實，且其有效成分及作用機制仍待進一步研究。

Taiwanese ropy fermented milk (TRFM) is a milk product with a ropy and sticky consistency, caused by slime-forming lactic acid bacteria (LAB) in the starter cultures producing exopolysacchrides (EPS). Since the texture and flavor of TRFM are similar to that of traditional Finnish fermented milk viili, we also call it “Taiwanese viili”. Four LAB strains (Lactococcus lactis subsp. cremoris TL1, TL3, TL4 and Leuconostoc mesenteroides TL2) and three yeast strains (Kluyveromyces marxianus TY1, Pichia fermentans TY2 and Saccharomyces unisporus TY3) have been isolated and identified previously in our lab by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). The purpose of this study was to further investigate the functional properties of TRFM and the microorganisms, including antioxidation, angiotensin converting enzyme (ACE) inhibition, in vitro immunoregulation, anti-allergic and anti-colitis effects in murine model. For antioxidative activities of TRFM, three methods including ferrous ion chelating, cupric ion chelating, and DPPH free radical scavenging were conducted. Results indicated that TRFM supernatant showed significant activities of scavenging DPPH free radical with a fermentation time manner but showed no any chelating ion ability. ACE is known to associate with hypertension and congestive heart failure. The TRFM samples demonstrated a significantly higher inhibition in ACE. For the immunoregulatory effects, TRFM samples and the microorganisms were co-cultured with murine macrophage cell line RAW 264.7 and murine splenocyte in vitro. TRFM samples and the LAB strains induced the production of TH1 cytokine TNF-alpha