Department of Food Science, Food Microbiology, University of Copenhagen, Frederiksberg, Denmark.
Lett Appl Microbiol. 2012 Mar;54(3):225-32. doi: 10.1111/j.1472-765X.2011.03195.x. Epub 2012 Jan 13.
In this study, we investigated the relationship between the ability of lager brewing yeast strains to tolerate oxidative stress and their ability to produce oxidative stable model beer.
Screening of 21 lager brewing yeast strains against diamide and paraquat showed that the oxidative stress resistance was strain dependent. Fermentation of model wort in European Brewing Convention tubes using three yeast strains with varying oxidative stress resistances resulted in three model beers with different rates of radical formation as measured by electron spin resonance in forced ageing experiments. Interestingly, the strain with the lowest oxidative stress resistance and lowest secretion of thioredoxin, as measured by Western blotting, resulted in the highest uptake of iron, as measured by inductively coupled plasma-mass spectrometry, and the slowest formation of radicals in the model beers.
A more oxidative stable beer is not obtained by a more-oxidative-stress-tolerant lager brewing yeast strain, exhibiting a higher secretion of thioredoxin, but rather by a less-oxidative-stress-tolerant strain, exhibiting a higher iron uptake.
To obtain lager beers with enhanced oxidative stability, yeast strains should be screened for their low oxidative stress tolerance and/or high ability to take up iron rather than for their high oxidative stress tolerance and/or high ability to secrete thioredoxin.
在这项研究中，我们调查了拉格啤酒酵母菌株耐受氧化应激的能力与其生产氧化稳定型模拟啤酒的能力之间的关系。
用二脒基和百草枯对 21 株拉格啤酒酵母菌株进行筛选，结果表明氧化应激抗性取决于菌株。使用三种氧化应激抗性不同的酵母菌株在欧洲酿造会议管中发酵模拟麦汁，通过强制老化实验中的电子自旋共振测量，得到了三种自由基形成速率不同的模拟啤酒。有趣的是，氧化应激抗性最低、硫氧还蛋白分泌最低（通过 Western blot 测定）的菌株在模拟啤酒中表现出最高的铁摄取率和最慢的自由基形成速度。
更耐氧化应激的拉格啤酒酵母菌株，表现出更高的硫氧还蛋白分泌，并不会产生更氧化稳定的啤酒，而是更不耐氧化应激的菌株，表现出更高的铁摄取率。
为了获得具有增强氧化稳定性的拉格啤酒，应该筛选酵母菌株，使其具有低氧化应激耐受性和/或高铁摄取能力，而不是高氧化应激耐受性和/或高硫氧还蛋白分泌能力。
