Environmental Effects on the Biochemical Phases of Malt Kilning. W. J. W. Lloyd, Pauls Malt Ltd., Key Street, Ipswich, United Kingdom. J. Am. Soc. Brew. Chem. 46:0008, 1988.

Malt quality is influenced by kiln environments during the three overlapping biochemical phases of malt kilning: germinative, enzymic, and chemical. These environments are affected by temperature and pressure sequences of the drying air and the bed depth. Analytical studies were made of malts taken from different locations in unturned commercial kilns and from pilot kilns of similar bed depth to assess the effects of humidity and temperature. Recommended procedures were used for malt analysis, and also some specialized methods, including 70° C mash viscosity, friability, and dimethyl sulfide (DMS) precursor determinations. Within-kiln differences showed that at the top of the kiln, where humidity levels were high for longer times, residual malt endo-β-glucanase levels were less despite lower mean temperatures than those at the kiln bottom. β-Glucan substrate degradation during kilning was higher in malt at the top kiln levels. Protein hydrolysis and the degree of friability were also enhanced in top-level malts; in contrast to endo-β-glucanase, residual α-amylase was higher. Pilot kilning investigations showed that changes in DMS precursors in malt were related to kiln environment. S-Methyl methionine present in malt loaded on to the kiln was partly degraded to free DMS, and a portion of this converted to dimethyl sulfoxide.

Keywords: Malt analysis, Kilning conditions, Enzymes, Friabilimeter, Nitrosamine, Dimethyl sulfide