Pulsed light inactivation of naturally occurring moulds on wheat grain

Abstract

Pulsed light (PL) is emerging as a non-thermal technology with excellent prospects for the decontamination of foods and food contact surfaces. Its application for mould inactivation on cereal grains would allow a reduction of storage losses as well as the prevention of mycotoxin contamination at a post-harvest level. The potential of PL for the decontamination of naturally occurring moulds on wheat grain was investigated in this study. Treatments of up to 40 flashes of a fluence of 0.4 J cm⁻² per pulse were applied to both sides of the grain, with an overall energy release ranging from 6.4 to 51.2 J g⁻¹. The most powerful treatment applied to wheat in this study (51.2 J g⁻¹) resulted in a mould reduction of approximately 4 log cycles on samples displaying an initial mould contamination level of 2.2 × 10⁵ CFU g⁻¹. At the same time, the seed germination percentage was only slightly affected. For PL treatments causing an inactivation of 3-4 log cycles, only 14-15% of the germination power of the wheat seeds was lost. The PL treatments attained greater microbial reductions for higher treatment times and lower initial mould loads. The absence of the UV portion of the radiation spectrum was found to significantly reduce the treatment effectiveness.