Effects of acidic water tempering and heat treatment on the Shiga toxin‐producing Escherichia coli (O121 and O26) load of wheat during tempering and its impact on wheat flour quality

Abstract

The study investigated the effects of acidic water (sodium bisulfate, SBS/lactic acid, LA) tempering (alone) and in combination with heat treatment on the Shiga toxin-producing Escherichia coli (STEC) O121 and O26 load of wheat and its impact on wheat flour quality. The results of the study showed that tempering wheat with acidic water (5 and 10% wt/vol) alone reduced its STEC load by 2.0 and 2.6 log CFU/g, respectively (p ≤ .05) after 24 hr of treatment. Heat treatment (55°C) significantly reduced the STEC load below detection limit (<1.6 log CFU/g) after 12 hr of treatment. The hurdle approach (5% acidic water + heat, 55°C) reduced the STEC load below detection limit within 6 hr of treatment. Finally, the wheat flours produced using the hurdle approach had lower pH (5.77–5.97) compared with the control without negatively affecting the baking and milling characteristics. Practical applications The study demonstrated that the hurdle approach of acidic water tempering coupled with heat treatment significantly reduce the Shiga toxin-producing Escherichia coli load of wheat without negatively impacting the wheat flour quality. Therefore, the combination of acidic water and heat treatment used in this study can be used as an antimicrobial intervention for improving the quality and safety of wheat-milled products.