Cereal Chem 65:118-122   |  VIEW ARTICLE

Storage of Wheat Malt: Sorption Properties and Water Activity Interrelations with Malt and Wort Characteristics.

T. Singh and G. S. Bains. Copyright 1988 by the American Association of Cereal Chemists, Inc. 

The interrelation of water activity (aw) and wheat malt and wort characteristics during storage was investigated. The sorption isotherm of wheat malt was sigmoid. For storage, equilibrated malts corresponding to aw of 0.112, 0.328, 0.52, and 0.756 were kept at 30 C and analyzed for changes in malt and wort characteristics at bimonthly intervals for eight months and at the end of 12 months. On storage, malts corresponding to aw of 0.112 and 0.328 showed some variation in diastatic power and alpha-amylase activity. Malts kept at 0.52 aw showed minimal changes in diastatic power and alpha-amylase activity and at the same time gave higher extracts. Except for the yield of extract, wich was satisfactory, deterioration in malt characteristics occurred when malts were stored at 0.756 aw. Analysis of data by response-surface methodology, applying second- and third-order polynomials, and by a linear correlation matrix showed that decreasing pH of worts caused by increasing aw of the malts affected wort characteristics considerably more than the duration of storage.