Comparison of Tempering Treatment Technologies for Pathogen Reduction on Wheat Grain

Outbreaks and recalls of wheat flour because of contamination with Salmonella or Shiga toxin-producing Escherichia coli (STEC) have raised concerns regarding food safety and generated interest in determining mitigation treatments that can be incorporated into existing unit operations. We examined four technologies that can be incorporated into the tempering step during flour milling. Wheat grain was inoculated with five-strain cocktails of Salmonella and STEC at 8 log CFU/g, and water activity was equilibrated, followed by a week of storage before tempering. Sterile tap water, lactic acid (LA at 5% and 20%), peracetic acid (PeraGrain 3000 and 6000 ppm), Neo-Temper (NT I and II), and hypochlorous acid (1200 and 2000 ppm) were applied at 4% (v/w) grain. With the exception of 5% LA and NT I for STEC, all technologies evaluated significantly reduced pathogen populations (P < 0.05) during tempering compared with the water control.