大豆與味噌中生物活性指標化合物之化學分析

Abstract

大豆含有許多具生理活性之植化素，其中以大豆異黃酮與大豆皂素為主，亦含有植物固醇與生育醇等脂溶性化合物，同時為良好的蛋白質、脂質等營養素來源。為瞭解台灣產大豆原料與其製成的發酵產品中質化素之含量，本研究欲利用高效液相層析串聯質譜儀搭配光學檢測器，分別建立兩個分析平台進行大豆異黃酮與大豆皂素、植物固醇與生育醇之測定，分析台灣產原料、實驗室製作味噌與市售味噌中植化素含量。在大豆異黃酮與大豆皂素之分析平台能夠測定到16種大豆異黃酮與19種大豆皂素，在大豆原料中異黃酮主要為丙二醯態，經由製成味噌則被微生物代謝為配醣體之形式，同時也產生3’-hydroxygenistein等代謝產物；大豆皂素主要以帶有DDMP (2,3-dihydro-2,5-dihydroxy-6-methyl-4H-pyran-4-one) 基團存在於大豆原料中，DDMP基團會因熱加工而使其掉落形成B group的大豆皂素，然而因其醣基種類複雜，味噌中微生物未能使其醣基結構上有明顯之變化。植物固醇與生育醇之同步分析平台中，能夠偵測到糖苷態、自由態與酯化糖苷態固醇，以及8種生育醇。在大豆原料中植物固醇以自由態為主，而製成味噌微生物中酵素作用後，則以糖苷態固醇為主。大豆經由微生物作用製成味噌後，植化素會產生不同的結構變化，藉由本研究之分析平台能夠作為分析植化素在發酵過程中結構變化之工具。

In addition to proteins and lipids, soybean is a good source of bioactive phytochemicals, i.e. isoflavones, soyasaponins, phytosterols and tocopherols. To effectively evaluate the contents of phytochemicals in Taiwanese soybean cultivars and its fermented product, miso, this research established two simultaneously analytical platforms, one for isoflavones and soysaponins and another for phyosterols and tocopherols using high-performance liquid-chromatography coupled with photodiode array detection (PDA) and tandem mass spectrometry (LC-MS/MS). There were 16 isoflavones and 19 soyasaponins simultaneously analyzed on the first platform. The malonylglucosides were the major isoflavone type of soybean raw material, nevertheless, they were converted into aglycones and metabolites such as 3’-hydroxygenistein by processing and microorganism in miso making. Soyasaponins with DDMP group is the major saponin type in soybean, after heat processing, soyasaponins with DDMP group would be degraded into B group soyasaponins. The second analytical platform simultaneously determined steryl glucosides, free sterols, acylated steryl glucosides and eight tocopherols. Free sterols were the major forms of phytosterols of soybean. The acylated steryl glycosides phytosterols were converted into steryl glycosides instead the free form of phytosterols in miso. The two analytical platforms developed in this study demonstrate to be effective tools to study the biotransformation in fermentation processing.