大曲氨基酸是大曲色泽形成的原因之一,同时能为微生物生长代谢提供氮源及为大曲香气合成提供前体物质.以酱香型白酒高温拆仓大曲(白曲、黄曲和黑曲)为研究对象,采用茚三酮衍生法研究了其游离氨基酸组成和差异.结果表明,黑曲中总游离氨基酸含量最高(12.52 mg/g),黄曲次之(10.57 mg/g),白曲最低(9.65 mg/g).从酱香型大曲中可检测出天冬氨酸、苏氨酸、丝氨酸、天冬酰胺、谷氨酸、甘氨酸、丙氨酸、缬氨酸、蛋氨酸、异亮氨酸、亮氨酸、酪氨酸、苯丙氨酸、鸟氨酸、赖氨酸、组氨酸、精氨酸和脯氨酸共18种氨基酸以及γ-氨基丁酸.白曲、黄曲、黑曲的不同游离氨基酸含量存在显著性差异(P<0.05),基于该18种游离氨基酸建立判别模型,可实现对酱香型白酒大曲类别的有效判别.通过对大曲游离氨基酸的分析,为进一步揭示不同类别大曲功能奠定理论基础.%Amino acid is one of the reasons for the color formation of Daqu, and can also provide nitrogen source for the growth and metabolism of microorganisms and precursors for the aroma synthesis of Daqu. In this study, the composition and difference of free amino acids in high temperature warehouse Daqu (Baiqu, Huangqu and Heiqu) from Moutai-flavor Baijiu were studied by using the method of ninhydrin derivatization. The results showed that the total free amino acids content in Heiqu were the highest (12.52 mg/g), followed by Huangqu (10.57 mg/g) and Baiqu (9.65 mg/g). 18 amino acids, including aspartic acid, threonine, serine, asparagine, glutamic acid, glycine, alanine, valine, methionine, isoleucine, leucine, tyrosine,phenylalanine, ornithine, lysine, histidine, arginine and proline, and gamma-aminobutyric acid, were detected in Moutai-flavor Daqu. There were significant differences in the content of different free amino acids among Baiqu, Huangqu and Heiqu (P<0.05). Based on these 18 kinds of free amino acids, a discriminant model was established to effectively discriminate the types of Daqu from Moutai-flavor Baijiu. Through the analysis of free amino acids in Daqu, this study laid a theoretical foundation for further revealing the functions of different types of Daqu.
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