RELATIONSHIPS BETWEEN MILLING ENERGY AND HOT WATER EXTRACT VALUES OF MALTS FROM SOME MODERN BARLEYS AND THEIR PARENTAL CULTIVARS

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Abstract
Determinations of hot water extract values of malts of some modern barleys and their parental cultivars correlated well (r = −0.71) with milling energy estimates made on ungerminated grain. This confirms previous findings that these grain attributes are negatively correlated over different sites and growing seasons. Three types of barley endosperm can be distinguished on the basis of milling energy determinations. Most barley cultivars that are difficult to malt or are classified as feed barleys have high milling energy values (ranging from 370 to > 400 mg trace weight). This includes a number of currently recommended cultivars with Hordeum laevitigum in their pedigree. A second endosperm type has significantly lower milling energy values than the feed barley group (ranging from 330 to 355 mg, trace weight); barleys in this category also produce malts with high hot water extract values, e.g. Wing, Proctor and Berac. All of these barleys have one of the sister lines, Kenia—Opal—Maja in their ancestry. The third endosperm type with a loosely-structured ‘mealy’ endosperm has very low milling energy values (280 to 315 mg, trace weight) and includes the cultivars Ark Royal, Triumph and Keg, which give very high hot water extracts from their malts. All of the barleys in this group have the European malting barley Kneifel (also with a very low milling energy) in their pedigree. The results strongly indicate that hot water extract values of malts of current European cultivars are mainly due to the milling energy attribute of the endosperm, or are closely linked to it. This endosperm attribute has been selected through pedigree crossing or in barley collections, from just a few older malting quality cultivars. Evidence that this attribute is not linked to Hordein protein patterns controlled by the hor 1 and hor 2 loci on chromosome 5, is also presented.