Screening of post-harvest decontamination methods for cereal grains and their impact on grain quality and technological performance

Cost-effective approaches for microbial decontamination of cereals are of great industrial interest to reduce post-harvest crop losses and consumer health hazards. The objective of this study was to screen a range of 13 treatments, including physical (high hydrostatic pressure, ultrasound, vacuum packaging and microwaves with and without sodium hypochlorite), chemical (hydrogen peroxide, sodium hypochlorite, acetic acid, sorbate, propionate, quaternary ammonium compounds, and cold plasma), and microbiological (lactic acid bacteria) decontamination, on artificially infected wheat prior to storage in a model system for 6 weeks. Each treatment success, compared to positive and negative controls, was evaluated based on fungal bio-mass and accumulation of 13 mycotoxins during storage. To estimate the treatments impact on grain quality and technological performance, a comprehensive flour analysis was carried out, including activities of important wheat enzymes, soluble protein distribution, and gluten characterisation. The treated grains were also used to bake whole grain breads. The breads were analysed for quality parameters such as specific loaf volume, crumb structure, and physical crumb texture. Best decontamination procedures were found to be vacuum packaging, high hydrostatic pressure, microwave, sorbate, and propionate treatments, which fully inhibited fungal development and mycotoxin production. Deterioration in grain quality for the use in baking was found due to the microwave treatment as a result of the internal heating. The comparison of traditional methods with the novel approaches revealed that the conventional methods remain superior to the novel approaches due to their simplicity and efficiency without negative impact on the grains.