Petr Kosin (1), Adam Broz (1), Jan Savel (1); (1) Budejovicky Budvar, N.C., Ceske Budejovice, Czech Republic


Stability, considered as the time from filling to the breakdown of quality, is easily defined from a microbiological or colloidal point of view—either to the completion of lag-phase growth of contaminating microorganisms, or respectively to exceeding haze over 2 EBC units. Although several methods have been described for sensorial stability evaluation, the generally accepted border between sufficient and insufficient sensorial freshness has not been set. Some producers use a prediction from the antioxidant capacity or various kinds of forcing tests; less spread is an analysis of the content of aged beer components. The drawback of prediction from antioxidant capacity is insufficient differentiation of real antioxidants (compounds of which oxidation does not change beer perceived quality, like SO2) from other oxidizable components of beer (compounds of which oxidation change beer perceived quality, like polyphenols, bitter acids, sugar reductones or amino acids). A more straightforward attitude is sensorial testing, which is usually performed as vertical (one batch through time) or horizontal (more batches of a given age) study. The drawback of vertical study is that results are valid only for a limited amount of batches; the drawback of horizontal study is lack of information about the course of aging. Our newly proposed method is a combination of vertical and horizontal study. For the purpose of this study 200 batches of the same beer brand were sensorially tested through aging. The results were statically processed to show how big variation is among batches and how fast pale lager is aging under defined conditions. Optimal processing of the data and expression of the results seems to be striped bar charts for multiple age of beer. Sensorial testing and proper statistical data processing is the only method for determination and monitoring of real sensorial stability.

  Petr Kosin received engineering (M.S. degree equivalent, 2006) and doctoral (Ph.D., 2012) degrees in brewing and malting at the Institute of Chemical Technology Prague, Faculty of Food and Biochemical Technology, Department of Fermentation Chemistry and Bioengineering, Prague, Czech Republic. He worked on both of his theses, “Application of Modern Methods for Yeast Activity Control in Brewery” and “Consumer Perception of Beer Qualitative Characteristics,” at Budweiser Budvar, N.C. in Ceske Budejovice. He has been working in research and development at Budweiser Budvar, N.C. since his graduation. He has been a member of the EBC Brewing Science Group since 2011.