麦麸发酵前后不同存在形态酚类物质中酚酸含量的变化及其抗氧化活性分析

以小麦麦麸为培养基,采用三株泡盛曲霉进行固态发酵,分别提取并采用高效液相色谱法测定麦麸发酵前后不同存在形态(游离型、酯苷结合型、糖苷结合型、碱解束缚型和酸解束缚型)的酚类物质中酚酸的含量,并通过DPPH自由基清除试验、还原力试验以及抗脂质过氧化试验,研究这些酚类物质的抗氧化活性。结果表明:未经过发酵的麦麸,束缚型酚酸在总酚酸含量中约占总量的80%,其酚酸类成分主要包括对香豆酸、阿魏酸、丁香酸、对羟基苯甲酸、咖啡酸、绿原酸、没食子酸、香草酸和肉桂酸等。发酵后的麦麸,游离型酚类物质的含量显著提高。抗氧化试验的结果显示,麦麸中碱解束缚型的酚类物质和发酵后麦麸的游离型酚类物质的抗氧化性较强。试验结果说明泡盛曲霉能促使被束缚的阿魏酸游离出来,使游离型酚类物质的含量及抗氧化性显著提高;而且抗氧化活性与酚酸的种类及含量有关,咖啡酸、丁香酸和阿魏酸含量高的酚类物质,其抗氧化性也较强。

Analysis of Phenolic Compounds Contents and Antioxidant Activities in Unfermented and Fermented Wheat Bran

In this study, solid state fermentation of wheat bran was performed by three Aspergillus awamori strains (GIM3.266, GIM3.4, GIM3.5, respectively). Different forms of phenolic components in wheat bran were extracted and analyzed using HPLC method. Furthermore, DPPH radical scavenging assay, reducing power assay and anti-lipid per oxidation assay were conducted to analyze the antioxidant activities of phenolic components. It was showed that 80% of the phenolic components existed in a insoluble-bound form in wheat bran and it mainly included p-coumaric acid, ferulic acid, syringic acid, p-hydroxybenzoic acid, caffeic acid, chlorogenic acid, gallic acid, vanillic acid and cinnamic acid, et al. The content of free phenolic components increased sharply after fermentation. It was indicated that alkaline-hydrolysable phenolic components of wheat bran and free phenolic components of fermented wheat bran exhibited higher antioxidant activities in this study. Conclusion: Aspergillus awamori could release the bound form of ferulic acid from wheat bran after fermentation which resulted in a sharp increase of the content of free phenolic components and its antioxidant activities. Moreover, correlations were found between the composition of phenolic components and its antioxidant activities. Therefore, phenolic components with high concentrations of caffeic acid, syringic acid and ferulic acid exhibited higher antioxidant activities in this study.