Inactivation of Escherichia coli, Salmonella enterica, Listeria monocytogenes, and Staphylococcus aureus in cricket powder (Acheta domesticus) using combined curcumin, blue light irradiation and mild heat treatment

For the food safety of edible insects, effective decontamination strategies need to be evaluated and developed. In this study, we investigated the efficacy of blue light (BL; 410/430/460 nm) at 65 mW/cm 2 and mild heating at 60 °C (MH) for 10 min, individually and combined, with and without curcumin (CUR), for the inactivation of Escherichia coli , Salmonella enterica , Listeria monocytogenes , and Staphylococcus aureus in cricket powder ( Acheta domesticus ). Color, moisture loss, water activity (a w ), lipid oxidation, water- and lipid-soluble antioxidant capacity, and vitamin E homologues were also assessed. Following CUR photoactivation with BL in aqueous suspensions, E. coli and S. enterica showed log reductions of 2.16 and 1.23, respectively, while L. monocytogenes and S. aureus exceeded 5 log. The E. coli and S. enterica cells showed characteristic curved trajectories on the flow cytometry plot, suggesting intermediate states rather than a direct transition from live to dead cells. Of the two, S. enterica retained more viable cells. In contrast, L. monocytogenes and S. aureus became entirely permeabilized, with no evidence of such intermediates. In cricket powder, BL and MH alone resulted in log reductions of 0.48 and 0.77 for E. coli , respectively, while the combined BL + MH treatment achieved a 2.74-log reduction. Curcumin significantly potentiated bacterial inactivation when combined with BL and MH, achieving a 6-log reduction of E. coli . For S. enterica , L. monocytogenes , and S. aureus , BL and MH alone again produced lower inactivation than their respective combined BL + MH treatments, which achieved log reductions of 1.41 (compared to 0.55 and 0.40 individually), 1.19 (0.34 and 0.46 individually), and 1.10 (0.41 and 0.21 individually), respectively. For S. enterica , adding curcumin increased the reduction to 1.82 log. For S. aureus , curcumin seemed less effective in potentiating the BL + MH effect. For L. monocytogenes , by contrast, curcumin increased the reduction to 1.60 log, significantly higher than that achieved with BL + MH. All treatments significantly reduced moisture content and a w , with the combined BL + MH treatment producing the greatest drying effect. The combined BL + MH treatment caused the greatest color shift (Δ E = 2.34) and the highest reduction in vitamin E (40% loss). With added curcumin, cricket powder showed the lowest antioxidant capacity after BL treatment. This reduced antioxidant activity appears consistent with the highest lipid oxidation observed, induced by BL via curcumin-mediated photooxidation. In contrast, vitamin E loss under BL + MH was limited to 20% when curcumin was present, alongside higher antioxidant activity in the curcumin-added powder. Combining curcumin with blue light and mild heat shows potential as a decontamination strategy for cricket powder, but requires further development and optimization to effectively address the limitations of BL-driven interventions in such products.