The homogeneity of commercial malts in relation to processing conditions.
Freeman, P.L. and Rehmanji, M.
Malts showing very similar results from conventional analyses can exhibit unpredictable differences in brewhouse performance. Various supplementary tests have been devised in an attempt to improve the predictability of malt brewing properties, but few of these have won general acceptance. In the investigations described, samples of Harrington barley, processed in a commercial maltings using two differet steeping plans with three and two immersions (each followed by an air rest) respectively, were taken at intervals during germination, kilned and analysed by the standard methods of the American Society of Brewing Chemists as well as being subjected to tests of friability and homogeneity, methylene blue endosperm staining and a thick mash filtration test. The ASBC analyses, friability and thick mash filterability were similar in both cases, but whereas triple immersion steeping led to an earlier onset of embryo growth and of the beginning of modification, double immersion steeping produced a more homogeneously modified finished malt, an earlier onset of the decrease in wort viscosity and more rapid development of a good methylene blue staining pattern. It was also found that highly friable malts sometimes suffer from excessive protein modification. However, the combined results of friability and homogeneity tests do provide a good indication of possible differences in brewhouse performance between malts showing similar results from standard analyses. In this case, different malting methods have been shown to produce different patterns of modification with significant effects on brewing properties.
Keywords : analysis friability homogeneity malt malting modification quality steeping