The evaluation of production yeast strains from the collection of the RIBM for HGB technology
2011
Kubizniakova, P.,Vyzkumny Ustav Pivovarsky a Sladarsky, Prague (Czech Republic)
The collection of brewery yeasts of the RIBM contains more than 130 different production strains but only few strains are frequently used. A better evaluation of their biochemical and technological properties can contribute to the expansion of the choice of suitable strains. One recently studied property is the suitability to produce strains for fermenting hopped worts used in HGB technology. Not every production brewery yeast strain can be used for fermentation of hopped worts used in HGB technology because high gravity worts are not ideal environments for the growth of brewery yeasts. The high osmotic pressure, the viscosity, the rising ethanol concentration during fermentation and CO2 are limiting factors for the use of a particular strain. The current approaches for evaluating production strains are very expensive and time consuming. Therefore, a simple method enabling a fast and cheap evaluation of the yeast's ability to grow in higher density worts and their tolerance to ethanol content under laboratory conditions was proposed. The growth was followed by the cultivation in worts with concentrations of 16 and 20 % w/w extract and with the addition of ethanol with total concentrations of 0, 5, 7 and 9 % v/v. The proposed method allows working with large sets of strains and makes it possible to select strains potentially suitable for HGB technology. A good tolerance to higher osmotic pressure and to higher ethanol concentration was found in 14 strains. These strains have the ability to ferment worts with very high initial extract concentrations.
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