Standard analysis of malt flour can mask the heterogeneity of hydrolytic enzyme
activity. Kernel heterogeneity can lead to brewhouse problems and a product
with unpredictable nitrogen and fermentable sugar content. The variability
between individual grains of important malting characteristics was measured in
malt samples produced under aerobic and anaerobic conditions.
Various parameters (including germinative energy, germinative capacity,
moisture content, β-glucanase activity, friability and homogeneity) were
measured to ensure that the 5 d aerobic Optic malt, produced in Heriot-Watt
university micromaltings, was viable and of commercial quality.
The 5 d aerobic malt kernels produced at Simpsons Maltings in Berwick-Upon-
Tweed were heavier than the micromalt. Commercially produced malt kernels
had higher levels of fermentable sugars and soluble nitrogen than the micromalt
despite lower α-amylase, β-amylase and ‘total’ limit dextrinase activity.
Differences between the 5 d aerobic micromalt and the 5 d aerobic
commercially produced malt are indicative of why micromalting cannot always
be used as a model system for what is happening industrially and must be
modelled on commercial practice.
Subjecting 5 d aerobic micromalt to 24 h anaerobic incubation resulted in
increased levels of fermentable sugars per l wort. 24 h anoxia also resulted in
increased α-amylase and limit dextrinase activities. There are potential
industrial applications for this anaerobic wort.
Limit dextrinase inhibitor protein present in crude extract prepared from mature
barley, eluted from a gel filtration column at a higher molecular weight than
expected. The limit dextrinase inhibitor protein either aggregates or binds to
other proteins in a high molecular weight complex.International Centre for Brewing and Distilling (ICBD)Lindisfarne Trus
