Cold plasma-mediated pesticide residue reduction and quality attribute modulation in cinnamon revealed by volatilomics and untargeted metabolomics.

To evaluate Cold plasma (CP) for pesticide residue control in spices, dried Cinnamomum cassia Presl bark pieces fortified with eight pesticides were used as a controlled postharvest model. Volatilomics and untargeted metabolomics were further used to explore the related quality-modulation mechanisms. CP promoted pesticide degradation, with higher removal efficiencies obtained at increased power and treatment time. The mean degradation percentages generally showed an upward trend with increasing plasma power and treatment time. Among the conditions examined, treatment at 1.3 kW for 10 min produced the highest mean degradation percentage for each of the eight pesticides, with values ranging from approximately 15% to 55% in fortified cinnamon bark. CP also altered the surface structure and water status of cinnamon, as indicated by stronger surface etching, reduced contact angle, and decreased bound water content. Volatilomic analysis identified 111 volatile organic compounds, mainly terpenoids. CP increased the detectable abundance of key flavor- and function-related compounds, including d-limonene, cinnamyl acetate, β-elemene, and α-/β-pinene, and 30 volatile markers were screened. Untargeted metabolomics identified 164 metabolites and 52 differential metabolites, which were mainly annotated to carbohydrate-related pathways. Meanwhile, DPPH radical-scavenging and FRAP reducing capacities were higher after CP treatment, whereas antibacterial properties remained generally stable. These results indicate that CP can reduce pesticide residues in cinnamon while improving volatile flavor release and maintaining functional quality, providing a basis for its application in green processing of spices and plant-derived foods.