Annual Progress Report on Malting Barley Research March, 2002

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β-glucans, it might be most instructive to determine the level of arabinoxylan in wort or
beer.
The overall objectives of this research area project are to (1) develop methodology for the
determination of arabinoxylans in wort in beer., and (2) to characterize the MW profile
of arabinoxylans present in wort and beer and to evaluate the influence of processing
parameters on these profiles. Both are Ph.D. thesis projects, and limited progress is
reported as the candidates have just begun research.
Method development for determination of arabinoxylans has focused on refinement of
the GC method originally described by Schwarz and Han (J. Am. Soc. Brew. Chem.
53:157, 1995). This method involves acid hydrolysis of freeze-dried beer solids and the
determination of xylose and arabinose as alditol acetates. A limited amount of
ruggedness testing has been conducted to date.
In terms of MW profile, work to this point has focused on development of isolation
procedures that will allow analysis of the entire amount of each polysaccharide without
interference from other polysaccharides or other materials. Experiments have been
conducted to evaluate selective enzymatic digestion of dextrins (with amyloglucosidase),
β-glucans (with lichenase), and arabinoxylan (with endo-xylanase). The very low
molecular weight carbohydrates (mono- to oligosaccharides) are removed by
ultrafiltration, and the remaining high molecular weight fraction will be analyzed by high
performance size exclusion chromatography (HPSEC) with light-scattering/viscometric
detection. Results to date have shown that the enzymes do not appear to exhibit side
activities, and thus are suitable for selective digestion. However, the ultrafiltration
method has not yielded acceptable reproducibility.
2. Fusarium Head Blight (FHB) and Malt Quality. Fusarium-related research
focuses on the control of Fusarium growth during malting, and assessment the
relationship between Fusarium infection levels and damage to the quality of the grain.
The use of a Geotricum starter culture in steeping has been reported to reduce Fusarium
growth and DON (Boivin, P. and Malanda, M. 1997 MBAA Tech. Quart. 34:96). We are
currently evaluating the use of a commercial Geotricum culture on samples from the
2001 crop in cooperation with Degussa BioActives (Waukesha, WI) and Institut Français
Des Boissons De La Brasserie Malterie (IFBM, Nancy, France). Several pilot-maltings
have been completed, but data for general release is not yet available. Cooperative
research on the use of physical treatments for control of Fusarium growth during malting
is being conducted with Dr Charlene Wolf-Hall (PI, Cereal and Food Science, NDSU). A
recently completed M.S. thesis project evaluated the effect of hot water sterilization,
UV/electron beam-, and gamma-irradiation on barley germination and FHB levels. This
preliminary study indicated that hot water sterilization (45 o C) may be effective in
reducing levels of viable Fusarium, without significant damage to germination.
Additional work in this area has been funded through a USDA-NRI grant.
A cooperative study with Dr Brian Steffenson (Plant Pathology, UM) and Dr Richard
Horsley (Plant Sciences, NDSU) on the relationship between Fusarium infection levels
and damage to the barley/malt quality has been ongoing for several years. Samples