ARS | Publication request: Osmolyte Concentration: A New Method for Determining Malt Quality

Submitted to: North American Barley Research Workshop Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: September 4, 2008
Publication Date: October 26, 2008
Citation: Duke, S.H., and Henson, C.A. 2008. Osmolyte Concentration: A New Method for Determining Malt Quality. In: North American Barley Researchers Workshop Proceedings, October 26-29, 2008, Madison, Wisconsin. p. 23.

Technical Abstract: The primary ASBC, IoB, and EBC methods for measuring malt quality, although frequently modified, have basically remained the same for decades and in some cases centuries. Recent studies have found that malt osmolyte concentrations (OC) are excellent predictors of malt extract (ME), diastatic power (DP), and ASBC method a-amylase activity (a-AA). Also, OC has been found to correlate much better with malt sugars than ME, DP, ASBC a-AA, Megazyme Ceralpha method a-AA, a-amylase activity, or limit dextrinase activity. These observations would indicate that OC better tracks the degradation of all soluble polymers such as starch, proteins, and ß-glucans that are important to maltsters and brewers. The intrinsic nature of malt OC is that it measures the total molar concentration of a solution and not the mass of material in solution as does ME. This characteristic of OC lends it to be more discriminating as to the composition of a malt or wort. For instance, the hydrolytic cleavage of 1 mol of maltopentaose in solution to glucose would result in a 500% increase in OC, but only a ca. 9.1% increase in ME. The increase in ME is strictly due to hydrolytic gain resulting from the insertion of a hydroxyl group and hydrogen from H2O with each hydrolytic cleavage of glucose from maltopentaose, whereas the increase in OC is due to the increase in osmolality of the solution due to cleavage of all a-(1'4) bonds of maltopentaose. The simplicity, rapidity, cost effectiveness, and accuracy of the OC method will be discussed.