Optimization of low-temperature nitrogen plasma in reducing fungi and aflatoxin human exposure through maize

Globally, aflatoxin contamination in maize remains a huge burden despite many interventions put in place. The use of low-temperature plasma to decontaminate the maize is a potential solution for ensuring the safety and extended shelf life of the grain. This study optimized the parameters and investigated the efficacy of low-temperature nitrogen plasma (LTNP) in destroying fungi and reducing exposure to aflatoxins in naturally contaminated maize from an endemic region. The study generated 17 experimental runs using the Response Surface Methodology (RSM) of the Box Behnken Design (BBD) with exposure time, pressure, and ionization density as independent variables. Quantitative exposure assessment was conducted using Monte Carlo simulations followed by sensitivity and scenario analysis to study factors influencing exposure and best aflatoxin-reducing plasma parameters. The best-fitting RSM model, the linear model, indicated that increased exposure time but not pressure and power led to a corresponding statistically significant decrease in the fungal load and aflatoxin content. LTNP reduced aflatoxin contamination to levels below all the main global regulatory limits. Numerical optimization of the percent reduction in aflatoxin and fungal load indicated that an exposure time of 1793.4 s, pressure of 0.98 pascal and ionization power of 189.8 W are required to achieve an optimal reduction of aflatoxin content of 82.6% and fungal load of 96.9%. Exposure assessment indicated high exposure especially for populations with lower body weight with ρ = -0.46 between body weight and exposure. The best LTNP combinations achieved aflatoxin exposure reduction results comparable to but with markedly less variation than existing practically used decontamination methods. Further optimization studies during upscaling are recommended, incorporating independent factors such as temperature and processing volume and outcomes such as organoleptic, physical, and chemical changes in the food matrices after treatment.