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The Cleaning Effect on Brewing Barley Using Vibrations during Wet Steeping
C. Mller, T. Kunz, F.-J. Methner

Nowadays, industrial malting plant process batches of up to 300 tons whereas achieving a homogenous malt quality within one batch is a major goal. Consequently, cytolytically badly modified or even ungerminated kernels may lead to lautering and filtration problems e.g. due to high remaining unhydrolysed β-glucan fractions. Hence, the homogeneity and cytolysis of a malt batch should be improved. In this study, a cement vibrator was used to treat barley with vibrations during wet steeping at a frequency of 180200 Hz in order to obtain the influence of sonic waves on the final malt quality. The input of sonic waves during steeping resulted in a faster water uptake and a considerably improved cleaning effect on barley. Higher steeping degrees and remarkably reduced microbial contaminations in turn led to faster and more homogenous germination by means of higher germination energies and malt homogeneities in comparison to a reference malt which was processed without sonic waves treatment. Furthermore, an improved lautering performance of the produced malts as evaluated by an in-house laboratory lautering test, was improved when treating with vibrations during wet steeping. Additionally, the cleaning effect of the vibrations resulted in remarkably lower iron content of the malts yielding an improved oxidative flavour stability of worts produced thereof as determined by electron spin resonance spectroscopy. Outcomes of these trials benefit the malting industry in terms of improving the malt homogeneity and quality.

Descriptors: sonic waves, vibrations, water uptake, microbiology, germination energy, homogeneity

BrewingScience Monatsschrift fr Brauwissenschaft, 68 (January/February 2015), pp. 29-37