The selection of a dried yeast strain for use in the apparent attenuation limit malt analysis (AAL) procedure

Abstract

This investigation identifies that Mauribrew Lager 497 strain of dried yeast can be used as a standard strain for the determination of malt apparent attenuation limit (AAL). It provides fermentability results for malt quality evaluation laboratories that are comparable to fresh brewery yeast. It was found that the optimal pitching rate in Congress wort (EBC Analytica, 1998, method 4.5.1), was 1 g per 200 mL, pitched at 25 C and fermented for 24 h at 20°C with agitation to complete attenuation. Preliminary trials also indicated that the Mauribrew Lager 497 dry yeast may be useful to brewers for determining the wort batch attenuation characteristics by the limit gravity test. In this case a pitching temperature of 35°C was found to be optimal with all other conditions as above. For the purpose of malt quality evaluation and brewery quality control the advantages of using a standard dry yeast strain include ease and convenience of use, consistency of quality, and uniformity between laboratories when they are located in separate geographic regions. © 2005 The Institute of Brewing & Distilling.