Variation in pH and lactate levels in malts

Abstract

Malt pH, defined as the pH of worts prepared by the Institute of Brewing Methods of Analysis, was examined in commercial malts from a single malting plant over four crop years, 1990 to 1993. Batch to batch variability was found, in addition to a distinct pattern within two of the years, with a gradual decrease in the winter months following commencement of malting of the new crop barley, followed by a subsequent increase in the late summer. Variability in pH and the longer term trend were not related to any measured processing variables or characteristics of the barley used for malting. Possible reasons for the differences in pH were examined and a negative relationship between malt pH and wort lactate content was demonstrated in a selection of malts from two crop years. A method is proposed for extraction and purification of lactate directly from malt and using this method it was shown that lactate in wort derives mainly from malt with only small amounts being produced during mashing.