57. Influence of the grist fractions on the final beer quality

Martin Zarnkow (1), Stefan Biberger (1), Andreas Frank (2), Fritz Jacob (1), Lei Zhang (1); (1) Research Institute Weihenstephan for Brewing and Food Quality, Technische Universität München-Weihen, Freising, Germany; (2) Bühler AG, Uzwil, Switzerland

Technical Session 16: Barley & Malt II
Tuesday, August 16  •  2:00–3:15 p.m.
Plaza Building, Concourse Level, Governor’s Square 14

Barley and all other brewing cereals are a natural product. Their attributes with respect to brewing performance and final beer quality are strongly influenced by climate, growing region, growing year, varieties, agronomical techniques, and so on. But, the art of brewing is to produce reproducible products. We have to react to these changes. The idea of the study was to crush the malt and fractionate over sieving devices and analyze the fractions based on the relevant malt attributes. With that knowledge, there are now two possibilities. One is to define the optimal malt and mix the fractions. The other is to perform optimal brewing conditions based on the attributes of each fraction and to create different new beers or mix the final products to the desired one. We used eight different sieve qualities and analyzed nine different fractions (whole malt, husk, >1.6 mm, >1.0 mm, >0.63 mm, >0.34 mm, >0.18 mm, >0.125 mm and <0.125 mm). A broad range of attributes has been analyzed: extract, water content, iodine value, attenuation limit, color, Kolbach index, soluble nitrogen, free amino acids, viscosity, diastatic power, alpha-amylase, beta-glucan, TBI, DMS-P, ferulic and cumaric acids, total polyphenols, tannins, pH value, gelatinization temperature, Ca, Mg, K, Na, Fe, Zn, Mn, Cu, Al, smell and taste. In some cases the differences in the fraction attribute have been according to the literature. Some of them not. The reason are found in the different questions they asked. One is what is the maximum potential of one attribute in one fraction? The other is what could be solubilized with a normal mashing system? As one example that is very important for the fermentation process: the zinc content. We found in the fraction <0.125 mm the highest content using a Congress mash. But, the husk had the highest content after acid hydrolysis. To find the right ratio between the fractions the optimal malt quality was defined. When the husk fraction was reduced up to 50% it showed really good results concerning overall beer quality. Using the different fractions and adjusting the brewing technique to the attributes is a very important future aspect.

Martin Zarnkow apprenticed as a brewer and maltster from 1989-1991 at a small brewery in Frankonia. Martin completed a Diplom-Ingenieur (FH) graduate degree with an option in brewing technology in 1996 at the TU München Weihenstephan. Martin worked as a brewmaster for one year in a medium-sized brewery in Germany. Since 1997 he has been at TU München. Martin is the head of research and development at the Research Institute Weihenstephan for Brewing and Food Quality. In 2010 he finished his external Ph.D. research at the University College of Cork, Ireland, on the subject “Proso Millet (Panicum miliaceum L.) a Sustainable Raw Material for the Malting and Brewing Process.”