Yeast inoculation from the tops of tanks is common in white wine fermentations. Our objective was to examine whether inhomogeneities occur in tanks following yeast addition from the top with and without brief stirring after inoculation. We investigated whether inhomogeneities affect fermentation kinetics and formation of acetaldehyde, acetic acid, and pyruvate in Riesling juices with low turbidity. Samples and temperatures were taken at multiple tank heights in pilot-scale (105 L) and industrial-scale (2500 and 7000 L) tanks to investigate the distributions of temperature, yeast, and fermentation products in tanks of different volumes and height-to-diameter ratios. When the tank was not stirred following inoculation, cell counts were higher in the upper tank section for multiple days. Fermentation started earlier at the top of the tank than at lower levels, as indicated by specific gravity measurements. The top and bottom of the tanks differed by up to 8.6°C and 0.040 in specific gravity. The inhomogeneities lasted four days in the 7000 L tanks. These results suggest slow yeast sedimentation and poor mixing in the downward direction during the early fermentation phase. During vigorous fermentation, all parameters were homogenously distributed. Brief stirring after yeast inoculation provided uniform conditions during the early fermentation phase, except for temperature differences due to natural stratification. Stirring also shortened the fermentation duration. The final pyruvate concentration was significantly lower when the yeast was stirred in, presumably due to better nutrient availability throughout the tank, reducing sulfur dioxide demand. No differences were observed in acetaldehyde and acetic acid concentrations. When yeast is not stirred in following inoculation, tank sampling valves and temperature sensors do not reflect the entire tank during the early fermentation phase, which will negatively affect process control.

中文翻译：

---

白葡萄酒发酵中酵母细胞、温度和发酵副产物的分布

从罐顶接种酵母在白葡萄酒发酵中很常见。我们的目的是检查在接种后从顶部加入酵母后，在有和没有短暂搅拌的情况下，罐中是否出现不均匀性。我们研究了不均匀性是否会影响发酵动力学以及低浊度雷司令果汁中乙醛、乙酸和丙酮酸的形成。在中试规模 (105 L) 和工业规模 (2500 和 7000 L) 罐的多个罐高度处采集样品和温度，以研究不同容积和高度的罐中温度、酵母和发酵产物的分布。直径比。当接种后不搅拌罐时，罐上部的细胞数连续多天较高。比重测量表明，发酵在罐顶部比在较低水平面更早开始。罐的顶部和底部的差异高达 8.6°C，比重相差 0.040。在 7000 升罐中，不均匀性持续了四天。这些结果表明在早期发酵阶段酵母沉降缓慢且向下方向混合不良。在剧烈发酵期间，所有参数均匀分布。酵母接种后的短暂搅拌在早期发酵阶段提供了均匀的条件，除了由于自然分层导致的温度差异。搅拌也缩短了发酵时间。当酵母被搅拌时，最终的丙酮酸浓度显着降低，大概是因为整个罐子里的营养物质更好，减少二氧化硫需求。在乙醛和乙酸浓度方面没有观察到差异。当酵母在接种后没有搅拌时，在发酵初期，罐体取样阀和温度传感器不会反映整个罐体，这将对过程控制产生负面影响。