Development of DEX-HOP multi-attribute decision model for preliminary hop hybrids assessment

Hops (Humulus lupulus L.) essentially contribute to the quality of the taste of beer and its flavor. Experimental hop breeding data from the Slovenian Institute of Hop Research and Brewing were used to create a model of an expert system based on the multi-attribute decision modeling methodology DEX. The DEX-HOP 1.0 model assessed and ranked individual hop hybrids' and hop varieties' breeding potential to be assessed and ranked. The model has 18 attributes, hierarchically grouped within four main attributes: Biology, Chemistry, Morphology and Brewing value. Furthermore, utility functions in the model were defined by sets of elementary decision rules throughout the entire hierarchy for all aggregated attributes. The central part of the model contains 144 decision rules, which were specified according to the model users' previous breeding experiences. Four Slovenian hop hybrids, A1/54, A2/104, A3/112 and A4/122, and a reference hop variety Hallertauer Magnum with the target characteristics of plant resistance and brewing value were used for the model assessment. Based on the breeding experiences and model results, overall and individual attributes' assessments were carried out. A3/112 and A4/122 reached the overall level of the reference variety and were thus assessed as appropriate for further breeding. In contrast, the attributes of A1/54 and A2/104 did not meet expectations in relation to the reference variety. Decisions based on the DEX-HOP 1.0 model assessment offered an additional tool for experts' final decisions in selecting appropriate materials for further breeding or the commercial use of hop plants. Test results validate the application of the model for further research. (C) 2010 Elsevier B.V. All rights reserved.