Integrated management of the risks of stored grain spoilage by seedborne fungi and contamination by storage mould mycotoxins – An update

Fungal spoilage of stored grains may occur when activity of water (aw) in cereal grain exceeds a critical limit enabling mould growth. Because it is not feasible to maintain all parts of large grain bulks below this critical moisture limit during prolonged storage time, an infection by seed-borne fungi is not rare in cereal grain stored under humid temperate or hot climates, inducing irreversible qualitative losses. Additionally, some fungal species produce harmful mycotoxins. The most harmful toxigenic species belong to the group of xerophilic species (genera Aspergillus and Penicillium). Because mycotoxin contamination of cereal grain is a worldwide issue for public health and a permanent concern for cereal-food industries facing the challenge of a permanent monitoring mycotoxin content in their primary matters, tolerable levels of mycotoxins are severely regulated worldwide. Mycotoxin-producing species growth is closely dependent of grain moisture levels enabling biological activity in grain ecosystem. Consequently, mould growth in stored grain bulks can be anticipated through early detection of grain and mould respiration. The prevention of mycotoxigenic fungi spoilage of stored grain can be managed by a preventive strategy. The main objective of the review was to describe the different methods, material and practices combined in such an integrated preventive approach. Some solutions potentially acceptable for the decontamination of moderately contaminated grain are also discussed. Integrated management of mould spoilage risks in stored grain is based on five pillars: i/Prevention of mould development by keeping grain moisture below the critical limit of fungal growth; ii/Accurate monitoring of grain aw and temperature changes during the storage period, associated to the monitoring of early indicators of respiration activity of storage fungi; iii/Reduction of grain bulk moistening trends by physical intervention means; iv/Use of physical treatments (ozone, grain peeling or abrasion) to limit mycotoxin contamination transfer to processed cereal products; v/Possible use of bio-competitive strains of fungi or bacteria to prevent the development of mycotoxigenic fungi in grain bulks. The future research needs on this topic are also evocated.