Influence of Beer Characteristics on Yeast Refermentation Performance during Bottle Conditioning of Belgian Beers

Abstract

Although bottle conditioning of beer seems a rather simple process, problems often arise in industrial practice. Lack of process control can result in variable batch-to-batch quality, while constant product quality should be maintained anytime. In the present study, the refermentability of several Belgian beers was investigated to reveal important beer-related compounds influencing overall yeast fermentation performance during bottle conditioning. Bottled beer was inoculated with freshly propagated yeast and fermentable extract. Growth and refermentation performance of a less ethanol-tolerant yeast strain was more affected by high initial beer alcohol levels compared with a more ethanol tolerant strain. Yeast growth seemed no prerequisite for the completion of the refermentation process but could be beneficial, especially when using a less ethanol-tolerant yeast strain. A decrease of yeast activity during bottle conditioning resulted in delayed or stuck refermentations as well as an altered beer flavor profile with off-flavors like acetaldehyde. Initial beer alcohol content greatly determined yeast refermentation performance, though other beer characteristics or process related compounds should be considered, as well as a synergistic effect of various adverse factors. When bottle conditioning was successfully completed, a CO2 saturated beer with slightly increased alcohol content and enhanced fruity flavor was achieved.