Investigation of the Microbiocidal, Antioxidant, and Cytotoxic Effects of Cinnamomum verum (Cinnamon), Origanum onites (Oregano Balls), and Origanum vulgare (Black Oregano) Hydrosols: A Model Food Environment-Driven Usability Study

Abstract This comprehensive study evaluated the antimicrobial efficacy, antioxidant capacity, and cytotoxicity of cinnamon ( Cinnamomum verum ), black oregano ( Origanum vulgare ), and ball oregano ( Origanum onites ) hydrosols, with particular focus on acidified cinnamon variants (3% ascorbic acid, CHC; 3% malic acid, CHM). GC–MS analysis revealed distinct chemotypes: cinnamon hydrosol was cinnamaldehyde-dominant (76.66%), while oregano hydrosols exhibited carvacrol-rich profiles. Black oregano demonstrated superior antioxidant capacity, with a total phenolic content (TPC) of 1286 mg GAE/L and DPPH/ABTS values of 3.07 and 4.24 mmol TE/L, respectively. Antimicrobial testing revealed that cinnamon-based hydrosols produced the largest inhibition zones against Candida albicans (34.06 ± 2.00 mm) and Aspergillus flavus (26.23 ± 0.50 mm), while acidification significantly enhanced their antibacterial potency. CHM achieved the lowest MIC values for multiple pathogens, including Klebsiella pneumoniae (1.45 ± 0.01 µL/mL) and Bacillus cereus (1.99 ± 0.01 µL/mL). In Kashar cheese washing trials, CHM demonstrated superior performance with mean log reductions of 2.52 across five pathogens at 45 min, with most antimicrobial effect occurring within the first 15 min. Zeta potential analysis revealed CH maintained electrostatic stability (-22 to -23.5 mV), while CHM's near-neutral charge (-2.55 to -3.52 mV) facilitated enhanced bacterial contact. Cytotoxicity assays identified workable dilution ranges preserving ≥ 70% fibroblast viability (in L929), supporting short contact and rinse-type use. These findings position acidified cinnamon hydrosols, particularly CHM, as promising natural surface decontaminants for food systems.