<p>A phosphomolybdate nanozymes doped with copper and iron particles (Cu,Fe-PMs) with excellent peroxidase (POD)-like activity was prepared by one-step microwave digestion method. It can oxidize the positively charged substrates such as 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H₂O₂, resulting in the formation of a blue compound. It is noteworthy that the POD-like activity of Cu,Fe-PMs was significantly boosted upon the incorporation of sodium dehydroacetate (DHA). This was attributed to the formation of complex&#xa0;between the Cu,Fe-PMs and DHA. On the one hand, DHA enhances the affinity of Cu,Fe-PMs for the substrate and exhibits superior catalytic properties. On the other hand, DHA also accelerated the valence state transformations between Fe³⁺/Fe²⁺ and Cu⁺/Cu²⁺, increased catalytic active sites and facilitate the generation of more reactive oxygen species (ROS) such as •OH with strong oxidation. Therefore, the current study successfully established a highly sensitive and reliable colorimetric sensor for detecting the DHA content in foods. The results indicated that the absorbance at 652&#xa0;nm exhibited a linear relationship with DHA concentration within the range of 0.0017—2.5&#xa0;μg&#xa0;mL⁻¹, achieving a minimum limit of detection (LOD) as low as 0.83&#xa0;ng&#xa0;mL⁻¹. The sensor was&#xa0;successfully applied to detect DHA in actual samples, with recoveries&#xa0;ranging from 91.59% to 103.35% and a relative standard deviation (RSD) not exceeding 3.64%. This demonstrates the reliable performance and consistent reproducibility of the analytical approach.</p> Graphical Abstract <p></p>