酿造过程中添加单宁对啤酒风味稳定性改进的评价

Evaluation of the addition of gallotannins to the brewing liquor for the improvement of the flavor stability of beer

烷醇-烯醛作为自氧化和脂肪降解的最后产物,其转化的增加量与strecker降解中醛类含量的增加都和啤酒风味变坏的程度相符。异α-酸的氧化反应,尤其是不太稳定的反式异构体会导致低俗、粗糙的苦味。几乎和脂肪酸氧化酶的含量一样,麦芽的抗氧化力和糖化条件也都是非常重要的参数,它们足可以影响麦芽及其它原料对氧化等不利影响的抗力。本项工作是研究用没食子单宁(以下简称单宁)来加强糖化过程中抗氧化能力的方法。单宁的作用很多,可以作为金属螯合剂,减少某些自由基。它们对乙醛的绑定和硫醇蛋白的凝结/絮凝也很有效。有关的分析数据,如氨基酸的strecker降解、脂类和异α-酸氧化及感官评价表明,单宁的添加有助于增加最终啤酒的风味稳定性。

Flavor deterioration coincides with an increase in a nd a release of alkanals-alkenals as final products of auto-oxidation and enzyma tic degradation of lipids and with a rise in Strecker aldehydes. Oxidative react ions on iso-a harsher bitterness. Next to the Lipoxygenase (LOX) content, the a ntioxidant power of the malt and the mashing-in conditions are important paramet ers prevent these adverse effects. This work deals with the use of gallotannins to increase the antioxidant powers during the mashing process. Gallotannins can act as metal-chelating, radical-scavenging, and reducing agents. They are also v ery effective in binding aldehydes and in the coagulation/fiocculation of thiol- containing proteins. The analytical data with regard to Strecker degrada tion of amino acids, oxidation of lipids and iso-a-acids, and sensory evaluation demonstrate that Gallotannin addition seems promising to increase