The effect of steeping regime on barley malt quality and its impacts on breeding program selection

Authors: TURNER, HANNAH - Montana State University; ELMORE, LIZ - Montana State University; Walling, Jason; LACHOWIEC, JENNIFER - Montana State University; MANGEL, DYLAN - Montana State University; FISCHER, ANDREAS - Montana State University; SHERMAN, JAMIE - Montana State University

Submitted to: Journal of the American Society of Brewing Chemists
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/6/2019
Publication Date: 7/30/2019
Citation: Turner, H.M., Elmore, L., Walling, J.G., Lachowiec, J., Mangel, D., Fischer, A., Sherman, J. 2019. The effect of steeping regime on barley malt quality and its impacts on breeding program selection. Journal of American Society of Brewing Chemists. https://doi.org/10.1080/03610470.2019.1629794.
DOI: https://doi.org/10.1080/03610470.2019.1629794

Interpretive Summary: The process of malting barley involves 3 distinct, but highly regulated steps: 1) Steeping of the grains, 2) Germination of the Grains and Kiln Drying of the grains. In a research setting the resulting malts go through a litany of test to determine quality. Therefore, it is of great importance to determine the variability in these processes when compared from lab to lab. Through a cross-comparison study, we determined that observed differences between malt quality analysis produced by USDA-ARS and MSU labs were primarily due to the steep regime. To isolate the primary difference, we compared the malt quality of seven lines steeped by three different regimes. Different traits responded differently depending on the regime. This is of importance to breeders, since the selection of the best performing line will depend on the steep regime employed. This study encourages future research to determine the genetic control of response to malt regime.

Technical Abstract: When making malt, the endosperm is hydrated during steeping to make stored starch available for extraction. Differences in steep regime impact malt quality. Here we report that differences in malt quality analysis between the USDA-ARS and MSU malt quality laboratories are primarily due to differences in steep regime. Evidence suggests that differences in steep regime in this study were primarily due to length of water immersion versus air rests, rather than other differences (e.g. temperature of steep, sorting of seed, or length of germination). The difference in steep regime caused a difference in the level of endosperm modification. To confirm this finding, we tested three different steep regimes on seven different lines and found that the impact on quality varied depending on the trait and in some cases on the genotype. We found that steep regime affected both moisture uptake and quality of hydration. Finally, we discuss the implications of these findings on malt quality analysis and breeding for malt quality.