The purpose of this diploma thesis was to study the influence of various factors affecting the fermentation process and the quality of beer. We were changing the original extract, the type and quantity of yeasts at inoculation, and the temperature under which fermentation took place. The experiment was carried out in three parallels, one of them was analysed after a few days and the other two were analysed in the end. The determination of the influence of different factors on fermentation kinetics was monitored gravimetrically by multiple intermediate weigh-ins. We found out that the kinetics was affected by all parameters, with the influence of temperature being the most obvious. The amount of apparent extract was measured directly in the beer, meanwhile the real extract was determined with a refractometer after distillation in the distillation residue. By distilling the samples we also obtained a distillate in which the alcohol content was determined. Based on these analyses, we found out that the amount of residual sugars and alcohol level in beer are most affected by the temperature in combination with the yeast strain used. To determine the value of FAN and bitterness in beer, we used reference methods. These showed less influence of the applied factors, of which the use of different yeasts stood out the most. The experiment demonstrated that the change of critical factors in the process of beer production can significantly affect the final product.
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