Determination of Cytolytic Malt Modification – Part I: Influence of Variety Characteristics

Abstract

The malt criteria of viscosity and β-glucan are used as an integral part of routine laboratory control measures to classify the cytolytic malt modification level and to ensure good processability. To optimize separation processes in general, the main focus of barley breeding has been on intensifying the cytolytic modification level and reducing the β-glucan concentration. However, not all new malting barley varieties show good processability despite a low β-glucan content, since the effect of hemicellulose constituents such as arabinoxylan and their enzymatic hydrolysis are largely disregarded. For this reason, the aim of the present work was to investigate the individual cytolytic composition of different malting barley (malt) varieties and to point out differences in cytolytic malt parameters depending on their genetically determined modification level. Appropriate analytical possibilities for arabinoxylan determination and suitable extraction methods for cytolytic evaluation have been further shortcomings in breeding quality control. In addition, the most important cytolytic degrading enzymes have been characterized in this paper. Part one of this two-part study demonstrated that cytolytically highly modified varieties have a lower β-glucan but in consequence a higher arabinoxylan content. With regard to the activity of enzymes, the results suggested small differences in β-glucanase, but not in arabinofuranosidase and xylanase. Finally, a principal component analysis showed that most of the cytolytically highly modified barley varieties (52%) were affected by arabinoxylan. The first part of the paper confirms that while breeding progress has reduced β-glucan, arabinoxylan has become the more dominant impact factor on processability.