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O-7. The different outcomes of bottle conditioning—How to choose the right yeast and parameters for the job

Presenter: Sylvie Van Zandycke, Lallemand Brewing, Milwaukee, WI. Coauthor(s): Tobias Fischborn, Lallemand R&D, Montreal, QC, Canada.

A reliable and consistent bottle conditioning process is a prerequisite to ensure beer quality and brand recognition. Brewers have different expectations from their bottle conditioning process, and understanding how to achieve the desired results starts with choosing the right yeast for the job. In many cases, it has been demonstrated that cropped yeast; which has been reused many times is of variable quality and does not perform as well as fresh yeast. Dry yeast offers a convenient alternative; fresh and consistent every time, it also has the advantages of long-term and easy storage. More importantly, it alleviates the lengthy process of cell counting, as the number of viable cells per gram (typically 5×109 to 1×1010) is often specified by the supplier. Bottle conditioning provides many benefits, including flavor enhancement and long-term shelf-life and is increasingly being used by craft brewers from all over the world. Reaching 100% carbonation with yeast alone is routinely performed in some breweries, while some others would rather partially carbonate and add less yeast. The outcome of the bottle conditioning process depends on several parameters such as the strain of yeast, the pitching rate, the type of beer to be refermented, the temperature, and also the priming sugar utilized to feed the yeast. More importantly, the combination of yeast and priming sugar is a determinant factor in a successful conditioning process. Indeed, not all yeast strains are able to utilize the full spectrum of sugars efficiently; this will in turn influence the organoleptic profile of the beer and refermentation performance. These parameters will be discussed based on an extensive study of low and high gravity Weiss beers refermented with different yeast strains in dry form. Tasting and analytical results will be provided, and recommendations for a successful bottle conditioning will be announced.

Sylvie Van Zandycke studied biochemical engineering and fermentation at the Institute Meurice (Brussels, Belgium); she completed her degree in September 1996. She then obtained her Ph.D. degree on Saccharomyces cerevisiae in July 2000 at Oxford Brookes University. From March 2000, Sylvie was employed as project manager for the brewing consultancy firm SMART Brewing Services. In 2004 she left the United Kingdom for Canada and accepted a post at Lallemand Inc. as project manager for their Genetic Identification Laboratory. She was involved with both yeast and bacteria QC and R&D, and her main focus in research was developing new methods for microorganism identification and characterization, as well as detection of contaminants in alcohol production processes. Since February 2007, Sylvie has occupied the position of brewing fermentation manager and, more recently, technical sales manager for Lallemand Brewing to service and support the brewing industry worldwide with dry yeast and nutrition products.