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Reduction in microbial load of soft wheat by tempering with organic acid and saline solutions
L. SABILLON (1), A. Bianchini (1), J. Stratton (1), D. Rose (1) (1) University of Nebraska - Lincoln, Lincoln, NE, U.S.A..

The microbial flora of wheat grains is the primary contamination source for milled products; therefore, reducing their load is desirable before or during processing. The objectives of this research were (i) to determine the efficacy of adding organic acids and NaCl to tempering water to reduce microbial load in soft wheat prior to milling, and (ii) to evaluate the effectiveness of combining organic acid and NaCl to reduce microbial counts. Wheat was tempered to 15% moisture under controlled (18h, 22-24°C 60% RH), aseptic conditions by adding water (control) or tempering solutions containing acid (acetic, lactic, propionic; 2.5% and 5% v/v) or NaCl (26.6% w/v). Wheat was analyzed before and after tempering for Total Plate Counts (TPC), yeasts, molds, coliforms, and<i> Enterobacteriaceae</i> (Eb). After tempering, the microbial load was significantly reduced by all treatments (p<0.05), when compared with initial levels. All acids at 5% concentration were able to reduce TPC counts, on average, by 1.9 log CFU/g. Lactic acid at 5% was the most effective against Eb (p<0.05), with an average reduction of 3.1 log CFU/g. In order to find a treatment that would further reduce the microbial counts, the tempering assay was repeated with combinations of antimicrobial agents. Wheat was tempered under the same conditions previously described by adding water (control) or tempering solutions containing acid (acetic or lactic; 2.5% and 5% v/v) and NaCl (26% w/v). The microbial load of the tempered wheat was significantly reduced by all organic acid-NaCl treatments (p<0.05). The combination of lactic acid (5%) and NaCl was the most effective against TPC and Eb (p<0.05), with an average reduction of 3.1 and 4.5 log CFU/g, respectively. Implementation of organic acids and NaCl in tempering water may have the potential to provide milled products with improved microbiological quality.