Reduction in microbial load of wheat by tempering with organic acid and saline solutions

Reducing microbial contamination in wheat is desirable to ensure consumer safety. In this study, the efficacy of adding organic acids and NaCl to tempering water to reduce microbial contamination in hard wheat was evaluated. Hard red winter wheat was tempered to 15.5% moisture by adding sterile distilled water (control) or tempering solutions containing organic acids (acetic, citric, lactic, or propionic; 1.0, 2.5, or 5.0 v/v), NaCl (26 or 52% w/v), or a combination of organic acid (acetic or lactic; 2.5 and 5.0% v/v) and NaCl (26 or 52% w/v). After tempering, the microbial load was significantly reduced by all the acid and NaCl treatments when compared with the control. Wheat tempered with 5% acetic, propionic, and lactic acids resulted in reductions of 1.7, 2.3, and 3.8 log colony forming units (CFU) per gram in aerobic plate count (APC), Enterobacteriaceae (Eb), and mold counts, respectively. The combination lactic acid (5.0%) and NaCl (52%) was the most effective against APC and Eb, with an average reduction of 4.3 and 4.7 log CFU/g, respectively. Tempering wheat with organic acids and saline solutions may provide milled products with improved microbiological quality when compared with the traditional tempering process using water.