啤酒酿造中二甲基硫、甲基蛋氨酸、二甲基亚砜含量的变化与控制

为控制啤酒风味物质二甲基硫（dimethyl sulfide，DMS）的含量，实验运用气相色谱-氢火焰离子化检测器测定了15 种国内市售啤酒样品DMS的含量，并研究了啤酒酿造中DMS、甲基蛋氨酸（S-methylmethionine，SMM）、二甲基亚砜（dimethyl sulfoxide，DMSO）的含量变化。结果表明，抽取的国内市售啤酒样品中有47%的样品DMS含量超出60 μg/kg，特别是爱尔啤酒（Ale）中71%的样品DMS含量超出60 μg/kg，最高值达到105 μg/kg；实验抽检10 种国内市售麦芽DMS、SMM、DMSO含量，不同麦芽间DMS与二甲基硫前驱体（dimethyl sulfide precursor，DMSP）差异较大，差异最高达160%，且多数小麦芽的DMS与DMSP含量低于澳麦芽。实验研究了麦汁煮沸、发酵过程中的DMS及DMSP含量的变化，在100 ℃、pH 5.6时，麦汁煮沸40 min后DMS含量比初始含量降低92%，SMM的半衰期为31 min。发酵过程中DMS含量在发酵旺盛期时有明显的下降，最高下降41%。

Changes and Control of Dimethyl Sulfide,S-Methylmethionine and Dimethyl Sulfoxide Contents during Beer Making

In order to control the content of dimethyl sulfide (DMS), a substantial contributor to the aroma and flavor of many commercial beers, 15 beer samples marketed in China were analyzed by gas chromatography with hydrogen flame ionization detection. Variations in the contents of DMS, S-methylmethionine (SMM), and dimethyl sulfoxide (DMSO) were traced during beer fermentation. The results showed that the content of DMS in 47% of the beers exceeded 60 μg/kg. Notably, 71% of the Ale-branded beer samples were found to contain DMS contents higher than 60 μg/kg (with the highest value of 105 μg/kg). Significant variation (up to 160%) was found among 10 commercial malts in the country in the contents of DMS and dimethyl sulfide precursor (DMSP). The contents of DMS and DMSP in most wheat malts were lower than those in Australian malts. After being boiled for 40 min at pH 5.6, the content of DMS in worts decreased by 92%, and the half-life of SMM was 31 min. Additionally, the content of DMS significantly decreased by up to 41% during the vigorous fermentation stage.