N2 controlled atmosphere reduces postharvest mycotoxins risk and pests attack on cereal grains

Mycotoxigenic fungi and pests are responsible for quality losses during medium to long-term storage of grain. Since gas composition is considered one of the most important abiotic conditions that influence fungal and pest growth, the use of a controlled atmosphere with a very high N concentration is a valid tool to control grain quality in post-harvest. Aim of the present work is to evaluate the use of a highly purified N controlled atmosphere - generated in situ by a Membrane Nitrogen Separator (Eurosider s.a.s) - for safely storage of corn and wheat grains. Two different parallel lab-scale experiments were performed in order to assess the effect of N atmosphere on: (1) the growth of Fusarium graminearum, Fusarium langsethiae, Aspergillus flavus and Fusarium verticillioides on agar and the production of aflatoxins on corn grains; (2) the populations of the most important post-harvest pests such as Sitophilus oryzae and Tribolium confusum on wheat grains and flour, respectively. When exposed to highly purified N controlled atmosphere (98.5%±0.5), growth and sporulation of all the four pathogens and aflatoxins production by Aspergillus were significantly reduced. In addition, atmosphere containing 98.5%±0.5 N caused the complete mortality of adults of S. oryzae after 3 days on wheat and of T. confusum after 7 days on flour. Results herewith reported suggest that N controlled atmosphere represents an eco-friendly tool that could be transferred to a large-scale system for grain storage in order to avoid or reduce chemical treatments.