Effect of Operational Parameters on the Determination of Laboratory Extract and Associated Wort Quality Factors. Paul B. Schwarz (1), Yin Li, John Barr, and Richard D. Horsley, Department of Plant Sciences. North Dakota State University, Fargo, ND. (1) Corresponding author. E-mail: Paul.Schwarz@ndsu.edu; Phone: +1.701.231.7732; Fax: +1.701.231.7723. J. Am. Soc. Brew. Chem. 65(4):219-228, 2007.

Mashing for the determination of malt extract and wort quality factors is one of the most fundamental analyses performed in malting and brewing laboratories. The origins of the Congress mash method date from the late 19th century, and dissatisfaction with the method has sometimes been voiced because the operational parameters do not necessarily reflect current commercial practices. The objective of this study was to evaluate the effect of operational parameters on the laboratory determination of malt extract and associated wort quality parameters. Two current malting cultivars, displaying three modification levels, were used in combination with three levels of grind, three grist/water ratios, and two mash temperature profiles. Grind clearly had the most marked effect and impacted all analytical values. The effects were greatest on extract. Temperature profile also affected all analytical parameters, but its impact was most obvious for wort color, beta-glucans, and fermentable sugars. Mash gravity had small effects on soluble protein and free amino nitrogen. Significant interactions involving modification often were observed, suggesting that observed differences were more pronounced as malt modification of samples decreased. The results of this study suggest that although the alteration of the laboratory mash parameters evaluated in this study may change the magnitude of differences between samples it is unlikely to change the overall actual rank of samples.