P-8
Relationships between common malt modification measurements.
RICHARD D. HORSLEY (1), Mary J. Wentz (1), and Paul B. Schwarz (2), (1) Dept. of
Plant Sciences, North Dakota State Univ.; (2) Dept. of Cereal and Food Sciences,
North Dakota State Univ.
Malting barley must be modified from a hard barley kernel to a friable malt kernel in a rapid uniform manner during the malting process. The barley also must meet certain quality standards to be used for malting. Many of the malt quality standards are measures of malt modification. Malt modification is the process by which the cell walls and protein matrix in the endosperm of the kernel are degraded by enzymatic activity during malting. Friability and Calcofluor staining assays are simple measures of malt modification that can be conducted in the malt house. More specific measures of malt modification are levels of malt beta-glucan, Kohlbach Index (KI), viscosity, fine-coarse extract difference, and free amino nitrogen (FAN). The objective of this study was to determine the associations between friability and Calcofluor staining, and other malt modification measures using simple linear correlation and multiple regression methods. Malt modification data, including viscosity, FAN, fine-coarse extract difference, KI, malt beta-glucan, and beta-glucan conversion, were collected on the Steptoe/Morex doubled-haploid mapping population and parents. Progeny and parents were grown at two locations in North Dakota in 1996 and 1997. Steptoe is a feed barley with poor malt modification characteristics. Morex is the malting and brewing industry standard for six-rowed malting barley with good malt modification characteristics. Progeny from the Steptoe/Morex population displayed a wide range of malt modification. The strongest associations between friability and Calcofluor staining were with malt beta-glucan. The correlation between friability and malt beta-glucan was -0.54. Between Calcofluor staining and malt beta-glucan, the correlation was -0.61. Multiple regression was done to determine if multiple malt modification traits explained the variation in friability and Calcofluor staining. No combination of malt modification traits significantly explained the variation in friability or Calcofluor staining. Malt beta-glucan explained 50% of the variation in friability and 59% of the variation in Calcofluor staining. Results indicate that friability and Calcofluor staining cannot be used to measure common malt modification measurements routinely used by the malting and brewing industry.
Richard Horsley is the six-rowed barley breeder and an Associate Professor in the Department of Plant Sciences, North Dakota State University (NDSU). He joined the faculty in 1988. He received a B.S. in Agronomy from the University of Minnesota, an M.S. in Agronomy from NDSU, and a Ph.D. in Crop and Weed Sciences from NDSU. His primary responsibilities are as head of the six-rowed barley breeding project. His research interests include identifying major genes that contribute to agronomic, disease resistance, and malting quality traits of barley using molecular mapping and conventional mapping techniques.