The Effect of Lactic Acid in Association With Steam in Reducing Microorganisms in Soft Wheat

ABSTRACT Background and Objectives Within the food industry, steam is an effective method of microbial reduction for a variety of products. Previous studies have shown that tempering soft wheat with organic acids, as well as steam application, can potentially reduce wheat's microbial load with minor changes in the functional properties of the flour. Thus, the objective of this research study was (a) to study the effect of saturated steam by itself or in combination with lactic acid, to reduce the natural microbial load of soft wheat, and (b) to evaluate the impact of these interventions on the functional properties of soft wheat flour. Findings Soft wheat samples were treated by adding acid to the tempering water, by steaming the kernels in replacement of the traditional tempering steep, or by pre‐conditioning the kernels with an acid solution followed by steaming as an alternative tempering process, thereby adding a combination of both. Samples were placed into sieves (bed depths 0.5 and 1.0 cm) for those treatments where steam was included. Grain was then treated on a stainless steel steam table until the grain temperature reached 80°C or 85°C. After treatment was applied, soft wheat was allowed to temper to 15.0% moisture. The combination of acid and steam was the most effective treatment tested ( p < 0.05). Specifically, at 85°C and a bed depth of 1.0 cm steam and acid combined achieved a 5.69 log CFU/g reduction in aerobic plate count and a 4.54 log CFU/g reduction in Enterobacteriaceae. Although several RVA parameters were significantly reduced by the treatments, these changes may be advantageous for certain applications (e.g., sponge cakes) while posing limitations for others that rely on higher paste viscosity. Conclusions According to the results, tempering done with steam alone or in combination with water for moisture adjustment was equally effective in reducing the microbial flora of wheat grains. However, the addition of acid as a pre‐conditioning agent further increased the microbial reduction for all microorganisms tested. Even though some significant differences were observed in the pasting properties of the straight‐grade flour, the baking quality of cookies was not significantly affected by any of the treatments. Significance and Novelty This study addresses the food quality and safety concerns related to microbial contamination in wheat flour by introducing a method utilizing lactic acid and steam treatment as part of the soft wheat kernels tempering step to reduce microbial loads while maintaining acceptable functional properties for selected low‐moisture applications. While the proposed intervention shows promise for improving microbial quality, its effects on flour functionality are application‐specific and warrant further evaluation for high‐moisture food systems.