MALT PROCESSING STABILITY OF BARLEY CULTIVARS — A STATISTICAL ANALYSIS

This paper presents a simple statistical analysis of malting process stability of barley cultivars grown for three years in the Mississippi Valley Six-rowed Uniform Barley Nursery and in the Western United States Two-rowed Uniform Barley Nursery. The effects of variety, location, and year on barley and malt quality were investigated. First, the Duncan Multiple Range Test was used to determine whether there were any varietal, location and year differences in barley and malt properties. The effects of variety, location, and year on various characteristics were further studied by comparing differences between extremes for the two-rowed and six-rowed barleys. Second, correlations between various properties were determined by calculating simple correlation coefficients. Barley nitrogen is the single most important parameter which affects extensively the processing characteristics of barley in malting and brewing, so the partial correlation coefficients, independent of total barley nitrogen, also were calculated. Third, the effects of variety, location, year, variety × location, variety × year, and location × year, were tested with variety × location × year as the estimate of error for each of the barley and malting properties. The stability model was designed to evaluate stability of all barley and malt properties. Based on the principle of regression analysis, the stability was measured by regression coefficient and the varietal mean of each barley and malting property. Stability (over years and locations) for kernel weight was significantly higher in the new than in the old cultivars. Improvements in stabilities of total extract and fine-coarse grind extract were greater and more consistent for the six-rowed than for the two-rowed barley malts. This reflects, presumably, the generally more satisfactory total extract and fine-coarse grind extract in the two-rowed barley malts than in the six-rowed barley malts.