The influence of malt quality on malt brewing and barley quality on barley brewing with Ondea Pro, compared by small-scale analysis
Evans, E and Redd, K and Harasmow, SE and Elvig, N and Metz, N and Koutoulis, A, The influence of malt quality on malt brewing and barley quality on barley brewing with Ondea Pro, compared by small-scale analysis, Journal of the American Society of Brewing Chemists, 72, (3) pp. 192-207. ISSN 0361-0470 (2014) [Refereed Article]
Brewing high quality beer efficiently requires good quality malt for conventional malt brewing or good quality barley for barley brewing with the Ondea Pro enzyme system. The potential brewing performance of both malt and barley were compared by using two similar small-scale mashing protocols, both variations on the EBC-Congress mashing protocol, which produced wort of a similar gravity and fermentability. This was achieved by mashing 93 different malt samples with the "Final 65°C" protocol and 137 different barley samples with the barley brewing protocol. The two different mash grist sources provided an opportunity to compare and contrast these two alternative brewing systems. Overall, barley brewing with Ondea Pro produces slightly lower levels of extract, while fermentability levels were somewhat lower than malt mashed with the Final 65°C protocol but comparable with the fermentability previously observed for malt mashed with the EBC-Congress protocol. For barley brewing, high levels of fermentability, comparable with the level achieved with malt (Congress protocol), result from the selection of the appropriate quality barley for brewing. Typically, barley from malting or food grade varieties that contain the highly thermostable Sd2H β-amylase type produced the highest levels of extract and fermentability. In addition, barley brewing assessment of samples from two subsequent growing seasons produced higher extracts that were equivalent to that achieved with malt, indicating a potential seasonal impact. The worts produced by both brewing systems were of similar pH and contained similar levels of Bradford protein. The barley brewed wort did have substantially higher levels of wort lipid (measured as total fatty acids) and lower levels of FAN, although previous investigations and our results suggest that this does not adversely impact yeast fermentation performance. With respect to wort filtering and lautering efficiency, barley brewed mashes/worts were substantially superior due to reduced wort viscosity and lower β-glucan content. This was despite the higher levels of wort lipid, presumably fatty acids, observed in barley brewed wort. With both malt and barley brewing, wort lipid levels were positively correlated with wort haze but were negatively correlated with lautering and wort filtration efficiency. These observations suggest that variation in the level of lipase activity in malt could potentially impact wort filtration and lautering efficiency. Malt and barley characteristics that potentially predict extract, fermentability, FAN, wort filterability, and lautering efficiency were assessed by step-wise multi-linear regression analysis and discussed. Overall, barley brewing was shown to be reproducible, efficient, and generally comparable to conventional malt brewing. The contrast between these two brewing strategies potentially identifies barley and malt quality parameters worthy of further study to improve brewing efficiency, and product quality, from both production systems.