ARS | Publication request: Fluorescence microplate readers as an alternative to flow injection analysis for determination of wort beta-glucan

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 20, 2008
Publication Date: August 2, 2008
Citation: Schmitt, M., Budde, A.D. 2008. Fluorescence microplate readers as an alternative to flow injection analysis for determination of wort beta-glucan [abstract]. In: World Brewing Conference Proceedings. World Brewing Conference. August 2-6, 2008, Honolulu, Hawaii. p. 81.

Technical Abstract: Selection of new barley varieties to meet the needs of the malting and brewing industry requires that the lines being developed meet a set of malting quality standards that have been developed to help maltsters and brewers predict the commercial performance of the barley and resulting malt. One important parameter of the malting quality determinations is the level of beta-glucan found in wort, since high wort beta-glucan levels are thought to predict potential problems with brewhouse filtration. Historically, malting quality assessments were made relatively late in the process of line development, when sufficient grain was available to allow production and use of the 55 grams of malt called for in the standard Congress wort production method (ASBC Malt-4). Recently, a modification of the Malt-4 method producing representative Congress worts with significantly smaller amounts (<200 mg) of malt has been presented (Schmitt et al., JASBC 64, 181 – 186 (2006)). This adaptation of the standard Congress mashing cycle allows malting quality assessments to be made much earlier in the breeding cycle, improving the efficiency of the malting-grade line selection process. However, the smaller volumes of worts produced with the new mashing protocol were not sufficient for measurement of wort beta-glucan by traditional flow-injection analysis systems referred to in Wort-18, the standard ASBC method for determination of beta-glucan in Congress wort by fluorescence. However, the chemistry that is the basis for Wort-18 is still appropriate for use in fluorescence detection systems utilizing smaller volumes of samples and reagents, such as commonly-available microplate fluorescence readers. In this presentation, we show that simple adjustments in sample volume and similar parameters allow the use of a fluorescence microplate reader as an alternative for determination of beta-glucan in Congress wort. In addition to making fluorescent beta-glucan analysis feasible for researchers with limited quantities of malt or wort, or those without access to suitable flow injection analysis systems, the microplate format beta-glucan analysis procedure allows a significantly greater number of sample treatments to be analyzed. Such increased analytical capacity may enable additional experimental treatments not previously feasible, such as spiking worts with internal beta-glucan standards to examine the possibility of wort-dependent signal quenching.