Abstract: In order to reduce the pollution of wheat flour by harmful microorganisms, this study analyzed the bactericidal effect of light emitting diode (LED) blue light treatment (430–470 nm, 36 W) on wheat flour with low, intermediate and high gluten contents inoculated with different concentrations of Escherichia coli and Bacillus cereus, and it also investigated the effect of LED treatment on the physical and chemical properties of wheat flour. The results showed that compared with the control group, LED blue light treatment for 5 h significantly reduced the numbers of E. coli and B. cereus in wheat flour by 4.9 (lg (CFU/g)) and 4.7 (lg (CFU/g)), respectively, and the bactericidal effect was positively correlated with illumination time. The water content and transverse relaxation time T21 and T22 of wheat flour were decreased by LED treatment, but the major form of water in wheat flour was not changed. The light treatment had no significant effect on the lightness, wet gluten content or protein aggregates of wheat flour. However, the greenness and yellowness decreased, and the binding between protein and starch in wheat flour became tighter. Thus, LED blue light treatment can effectively inhibit the quality deterioration, increase the stability and improve the quality of wheat flour.

Key words: light emitting diode blue light; wheat flour; bacterial decontamination; physicochemical properties; quality