The occurrence of recalls involving pathogenic Escherichia coli-contaminated wheat flours show the need for incorporating antimicrobial interventions in wheat milling. The objectives of this study were to assess the efficacy of sodium bisulfate (SBS) tempering in reducing E. coli O121 (ATCC 2219) and O26 (ATCC 2196) wheat load and to evaluate the impact of effective (≥3.0 log reductions) SBS treatments on wheat flour quality. Wheat grains were inoculated with E. coli (~6 log CFU/g) and tempered (17% moisture, 24 h) using the following SBS concentrations (%wheat basis): 0, 0.5, 0.75, 1.0, 1.25, and 1.5% SBS. Reductions in E. coli O121 and O26 wheat load at different time intervals (0.5, 2, 6, 12, 18, and 24 h) during tempering were evaluated. The addition of SBS during tempering resulted in E. coli (O121 and O26) log reductions of 2.0 (0.5% SBS) to >4.0 logs (1.5% SBS) (p ≤ 0.05). SBS tempering (1.25 and 1.5% SBS) produced acidic wheat flours (pH = 4.51–4.60) but had comparable wheat flour properties in terms of composition, dough, and bread-making properties relative to the control (0% SBS). SBS tempering reduced the E. coli O121 and O26 load of wheat after tempering with minimal effects on wheat flour quality.

Non-thermal hurdle approaches could improve decontamination efficacy in food products without compromising quality. This study evaluated the effects of UV-C and acidic water tempering treatments in reducing the Shiga toxin-producing E. coli (STEC) contamination on wheat grains and its potential effects on the wheat flour produced. Hard red winter (HRW) wheat grains were inoculated (high: 6.4 ± 0.1 log CFU/g and low: 4.7 ± 0.2 log CFU/g) with STEC O121 / O26 and treated with UV-C (255 to 280 nm; 0 to 80 mins exposure time) alone or in combination with acidic water (5% lactic acid - LA) tempering (18 h). UV-C exposure (280 nm) from 10 - 80 mins resulted in STEC load reductions (P < 0.0001) ranging from 1.4 - 2.3 logs and 0.4 - 1.3 logs at high and low inoculation levels, respectively. Combining both acidic water tempering and UV-C (280 nm, 40 mins) resulted in an STEC load reduction of 2.3 - 3.6 logs within 12 h of tempering. The combined treatment (UV-C and LA) showed a synergistic effect (O/E ratio > 1; 1.1 - 1.3) against pathogenic E. coli as shorter times were needed (≈ 6 h) for a 3-log reduction relative to the individual treatments. This was supported by the lower (P < 0.05) predicted time required for a 3-log reduction (9.4 to 13.0 h) relative to the individual treatments (≥ 28.9 h). The LA/UV tempering treatment produced whole wheat flour with comparable color profile, particle morphology, solvent retention capacity, and pasting properties to whole wheat flour produced with conventional tempering (water). This study showed the potential of UV-C and acidic water tempering as an effective hurdle approach combination for mitigating E. coli contamination on wheat grains without affecting quality. These findings can be used as basis for addressing enteric pathogen contamination of whole wheat flour.

The rising demand for using raw meat diets (RMBDs) for feeding companion animals requires improvement in their food safety. Organic acids could be a promising anti-microbial ingredient for mitigating pathogen contamination. This study investigated the effects of encapsulated (E) and raw (R) acids (citric—CE and CR; lactic—LE and LR) on Salmonella survival in RMBDs during refrigerated storage. The acidulants (1.0% LE, 1.0% CE, 0.5% LE + 0.5% CE, 0.5% CE + 0.5% LR, 0.5% LE + 0.5% CR, and 0.5% LR + 0.5% CR) were incorporated in RMBD patties inoculated with Salmonella (ATCC 8326, ATCC 14802, and ATCC 13076) at 6 and 9 log CFU/patty levels. Inoculated (PC) and non-inoculated (NC) patties made without acidulants were used as controls. Patties were stored at 4 °C and Salmonella enumeration was done at days 0, 1, 4, 7, 10, 13, 16, 19, and 22. Salmonella reduction was higher (p < 0.05) in stored patties with both encapsulated and raw acids (3.10–4.10 logs) added relative to using individual encapsulated acids (2.40–3.70 logs) and control (0.70–0.90 logs). Higher inoculation levels resulted in greater (p < 0.05) Salmonella reductions in the patties after storage. The reductions were influenced (p < 0.05) by the treatment × time interaction with longer storage time resulting in higher reductions. The Salmonella inactivation under all acid treatments followed the Weibull model (R²—0.86 to 0.98; RMSE—0.19 to 0.34; β—1.23 to 2.08). The results show that encapsulated organic acids can inhibit Salmonella growth and survival in RMBDs under refrigerated conditions. The results from this study could be used as basis for improving the food safety of RMBDs.