To clarify the mechanism of the effects of cold plasma-sun drying process on pesticide residues during the drying process of Lycium ruthenicum Murr.

The 6 kinds of commonly used pesticides in Lycium ruthenicum Murr, namely acetamiprid, carbendazim, imidacloprid, pyridaben, fenpyroximate and zeta-cypermethrin, were selected as the research objects. The pesticide residues in each drying stage were determined by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), and the dynamic changes of processing factors (PF) and degradation rates were systematically analyzed. The residue change mechanism was explored in combination with the physicochemical properties of pesticides and process parameters, and a dietary exposure risk assessment was conducted.

Each drying procedure exerted significantly different effects on pesticide residues. Water washing exhibited the best residue removal performance, with degradation rates of 34.88%–73.14% for acetamiprid, carbendazim, imidacloprid and pyridaben. Only fenpyroximate and etoxazole underwent degradation after cold plasma treatment. After the drying process, all target pesticides did not show degradation effects. The dietary exposure riskassessment showed that the acute risk rate and chronic risk rate of the 6 kinds of pesticides were 0.001%–0.233% and 0.001%–0.167 % respectively, both far below the safety critical values.

The study confirms that the combined drying process of Lycium ruthenicum Murr is safe for consumption and can provide theoretical basis and data support for pesticide residue control and process optimization in Lycium ruthenicum Murr processing.