Effects of plasma-activated water and mild heating on Escherichia coli inactivation during wheat tempering and flour quality

Background and Objectives

Heat treatment, as a pathogen reduction step, could compromise flour quality. Plasma-activated water (PAW) is a novel pathogen reduction treatment for foods. Combining these treatments could improve pathogen inactivation during wheat tempering and maintain flour quality. This study evaluated the effects of PAW and mild heating on Escherichia coli inactivation during wheat tempering and wheat flour quality.

Findings

E. coli was inoculated into wheat grains at 6.0 ± 0.1 log CFU/g. A 5-log reduction was achieved after 6 h of tempering with PAW and heating (55°C), whereas 12 h were needed when using heating and deionized water (DI). Tempering with DI (control) and PAW alone only produced a 1-log reduction after 24 h. The PAW and PAW + heat tempering treatments produced flours with comparable yield, physicochemical, dough rheology, and bread characteristics compared to the control treatment.

Conclusion

Mild heating and PAW tempering demonstrated a synergistic effect as it produced greater E. coli reductions at shorter tempering times compared to the individual treatments. The hurdle approach used in this study did not compromise flour quality.

Significance and Novelty

The demonstrated hurdle approach can be a viable pathogen mitigation step in wheat milling which could help improve food safety of wheat-based foods.