Yujuan Wang (1); (1) North Dakota State University, Fargo, ND, U.S.A.
Malt and Grains
While rye has been used by the baking and distilling industries for centuries, its use in brewing has traditionally been limited. However, rye has recently become more popular as its addition can contribute spicy or pumpernickel characteristics to beer flavor. The malting of rye and use of rye malts presents several challenges to maltsters and brewers. These include the lack of a hull, dense packing in steep, extreme shrinkage in the kiln and a high content of water-soluble arabinoxylans. There is empirical evidence that rye genotypes differ in malting and brewing performance and flavor, but there is little published information on the malting of rye or the malt quality attributes of rye genotypes. The main objective of the current work was to evaluate laboratory micromalting conditions that could be used in quality screening. Key objectives were achieving high extract, with minimal malt loss and lower wort viscosity/arabinoxylan content. The experiment was conducted using a factorial design with rye sample (n = 2), kernel size fraction (n = 2:5/64 in. and ≥ 6/64 in.), steep-out moisture (n = 3:40, 45, and 48%) and germination time as variables (n = 4: 3, 4, 5, and 6 days). Malts were mashed according to the Congress method, but worts were centrifuged prior to filtration. Wort arabinoxylan and phenolic acid content were determined in addition to standard malt quality parameters. Data were analyzed using analysis of variance. Sample was found to impact all parameters, with the exception of FAN and arabinoxylan. Steep-out moisture did not influence extract or arabinoxylan level, but increasing moisture was found to increase malt loss and decrease viscosity. Germination time increased extract values only up to 4 days, but longer times contributed to lower viscosity and greater malt loss. Significant interactions between some parameters confounded the interpretation of data, but in general, high extract and lower viscosity were achieved by malting for at least 4 days at high moisture. Several commercial maltsters, however, have indicated that the handling of germinating rye at high moisture levels is problematic. As such we recommend 6 days of germination at 45% moisture for future evaluation of rye cultivars.
Yujuan Wang is an graduate student in cereal science from North Dakota State University (Fargo, ND). Currently, she is performing research in the area of malting and brewing technology. In 2015, Yujuan was awarded the Rahr Malting Scholarship from the Plant Sciences Department. That same year, she received a Statistic Certificate in applied statistics, and she will receive a Graduate Certificate in food protection in 2016.