Continuous microwave processing as a strategy to restrain Aspergillus contamination and mycotoxins in almonds

Fungal and mycotoxin contamination represent major safety concerns in almond production, particularly under conditions favorable to the growth of Aspergillus species. This study evaluated the effectiveness of a continuous-flow microwave (MW) system in reducing fungal contamination and mycotoxin levels in almonds Prunus dulcis (Mill.). Almonds were artificially inoculated with Aspergillus carbonarius , A. flavus and A. niger and treated at different MW intensities (30–80 Hz). The same treatments were applied to fungal culture broths containing aflatoxins and ochratoxin A. MW exposure completely inhibited spore germination of all the tested fungal species, achieving total inhibition across all treatment intensities. In inoculated almonds, also the lowest MW treatment reduced fungal infection by 95% for A. flavus and 92% for A. niger and A. carbonarius . In culture broths, aflatoxins and ochratoxin A concentrations decreased by 22% and 14%, respectively, while in contaminated almonds, reductions of 15.0% for aflatoxins, and 17% for ochratoxin A were recorded. Statistical analysis confirmed significant differences (p < 0.01) between treated and untreated samples. These findings demonstrate that continuous MW technology effectively limits fungal development and partially reduces mycotoxin concentrations in almonds, providing a sustainable, chemical-free, and scalable solution to enhance the safety and quality of nut-based foods.