Abstract Respiratory deficient cells or “petites” are the most common type of mutation found in brewing yeast. High levels of petites are known to contribute to unwanted flavors in beer along with yeast flocculation problems during fermentation. However, a minimal amount is known regarding the impact of petites when present at naturally occurring frequencies. Accordingly, this study investigated if petites, which are present at low frequencies, affect beer flavor and fermentation profiles. Laboratory [20 mL] fermentations were undertaken with yeast that contained a range of petite populations 3.7, 5.1, 8.7, and 10.8%. During fermentation, the yeast in suspension, wort density, and alcohol were monitored. At the end of the fermentation, the beer was analyzed for volatile flavor compounds. Correlations between petite levels and levels of vicinal diketones, acetate esters, and medium chain fatty acid (MCFA) ethyl esters existed. Higher alcohol levels were unchanged (propan-1-ol, 3-methyl butanol, 2-methyl butanol, and isobutanol) with increasing levels of petite concentrations. Similarly, the yeast in suspension behavior and the change in wort density attenuation between the control and petite enriched fermentations were not significantly different (P > 0.05). This study suggests that low concentrations of petites in the pitched yeast would not be detectable in the final product characteristics.

中文翻译：

---

人工诱导呼吸缺陷酵母对啤酒风味和发酵的影响

摘要 呼吸缺陷细胞或“小细胞”是酿造酵母中最常见的突变类型。众所周知，高含量的小颗粒会导致啤酒中出现不需要的风味以及发酵过程中的酵母絮凝问题。然而，当以自然发生的频率出现时，关于娇小的影响的最小数量是已知的。因此，本研究调查了出现频率较低的小啤酒是否会影响啤酒风味和发酵特性。实验室 [20 毫升] 发酵是用酵母进行的，酵母含有一系列 3.7、5.1、8.7 和 10.8% 的小种群。在发酵过程中，监测悬浮酵母、麦芽汁密度和酒精度。在发酵结束时，分析啤酒的挥发性风味化合物。小分子水平与邻位二酮、醋酸酯和中链脂肪酸 (MCFA) 乙酯水平之间存在相关性。随着小浓度水平的增加，较高的酒精水平没有变化（丙-1-醇、3-甲基丁醇、2-甲基丁醇和异丁醇）。类似地，酵母悬浮行为和对照发酵和小型富集发酵之间麦汁密度衰减的变化没有显着差异（P > 0.05）。该研究表明，在最终产品特性中无法检测到投过酵母中的低浓度小分子。类似地，酵母悬浮行为和对照发酵和小型富集发酵之间麦汁密度衰减的变化没有显着差异（P > 0.05）。该研究表明，在最终产品特性中无法检测到投过酵母中的低浓度小分子。类似地，酵母悬浮行为和对照发酵和小型富集发酵之间麦汁密度衰减的变化没有显着差异（P > 0.05）。该研究表明，在最终产品特性中无法检测到投过酵母中的低浓度小分子。