Microbiological Quality of Wheat Grain and Flour from Two Mills in Queensland, Australia

Abstract

A baseline investigation of the microbiological quality of wheat grain and flour from two mills in Queensland, Australia, was undertaken in order to assess the capacity of these two mills to meet microbiological criteria specified by a customer for raw, non–heat-treated flour. This baseline testing was performed over the 2006 to 2007 wheat season. Three hundred fifty flour samples were monitored for yeast, mold, and Bacillus cereus, 300 for Escherichia coli, 150 for Salmonella, and 100 for aerobic plate count. Fifty grain samples were analyzed for yeast, mold, E. coli, Salmonella, and B. cereus. There was a single isolation of Salmonella Give in unscreened wheat. The yeast, mold, E. coli, and B. cereus prevalences were 56, 40, 2.0, and 4.0% for grain and 71, 17, 0.7, and <0.3% for flour, respectively. Of the positive samples, the means were 3.7, 2.7, 0.6, and 2.1 for grain, and 3.0, 2.8, and 0.8 log CFU/g for flour. The mean of the aerobic plate count was 4.2 log CFU/g with a 95th percentile count of 4.6 log CFU/g. A microbiological quality baseline of wheat grain and flour from these two Queensland mills has been determined. These data in a specific sense assist the two mills to assess their capacity to meet microbiological criteria, and in a general sense provide at least a limited snapshot of Queensland wheat and flour quality for risk assessments being carried out to evaluate the safety of plant and plant products.