Malt Modification - A Century Of Evolving Views

Abstract

This lecture is the 22nd to commemorate Horace Taberrer Brown, a truly remarkable polymath who made important contributions to brewing practice and science and to 'pure' science. The ideas that Brown and his collaborators developed in the 1890s regarding the origins of the enzymes which catalyse the modification of the endosperm of germinating barley and how modification progresses through the grain are summarized, then the stages by which our understanding has been enhanced are noted. The discovery of gibberellins, their use in malting, the role they play in germinating grain, and how this knowledge has suggested ways to make malts with reduced malting losses are outlined. The discrepant reported patterns of modification and true 'average' patterns are described. It is pointed out that abrasion does not work by inducing two-way modification, as originally proposed. This successful process probably depends on improved access of oxygen to the living grain tissues. Microbes on the grain compete with the embryo and aleurone layer for oxygen, to the detriment of germination and modification. Commercially acceptable ways in which the activities of microbes might be reduced (and malting enhanced) are discussed, including the use of plug-rinses at the end of steeps to reduce the microbial population and the quantity of the microbial nutrients which support growth and respiration and are dissolved in the water around the grains. A newly-proposed method for the bulk-selection of malting quality lines from mixed populations of barley is mentioned. Finally, the dangers to the malting and brewing industries in the U.K. of the continuing reduction in scientific research is indicated.

The effects of GA and ABA treatments on metabolite profile of germinating barley

“…Obviously it may be attributed to enhanced protease activity by GA, as it was reported by some researchers (Briggs, 2002;Enari & Sopanon, 1986). The released amino acids could provide the sufficient substrates for biosynthesis of proteins and enzymes, being necessary for seed germination.…”

“…The released amino acids could provide the sufficient substrates for biosynthesis of proteins and enzymes, being necessary for seed germination. GA also promotes cell wall modification and degradation (Briggs, 2002;Enari & Sopanon, 1986), as reflected by increased β-glucanase activity ( Fig. 1), a key enzyme involved in cell wall degradation (Forrest & Wainwright, 1977).…”

A theoretical framework for β-glucan degradation during barley malting

“…Progressive extension of cell wall modification is a characteristic feature of the in vivo degradation of the barley endosperm (Brown and Morris 1890;Briggs 2002), and is linked to peculiar conditions for b-glucan breakdown. In fact, Gianinetti et al (2007) experimentally demonstrated that, during malting, b-glucan degradation follows pseudo-first-order kinetics.…”

The Horace Brown Medal Lecture: Forty Years of Brewing Research

“…His contributions were remarkable and his focus was to solve practical brewing problems by employing and developing fundamental scientific principles. A number of previous recipients of the Horace Brown Medal have reviewed Brown's achievements in detail 14,73,105 . However, a brief summary here of Brown's research is appropriate.…”