Biological Activities of trans ‐Nerolidol–Rich Chamaecyparis obtusa Essential Oil and Its Application in Lettuce Preservation

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Chinese hinoki essential oil ( Chamaecyparis obtusa (Siebold & Zucc.) Endl.; HEO) was characterized by GC‐MS, and its antimicrobial, insecticidal, and potential preservative activities were evaluated. The analyzed essential oil exhibited a trans ‐nerolidol–dominant composition, contributing additional data to the currently limited information available for Chinese C. obtusa chemotypes. The oil exhibited an unusual sesquiterpene‐dominant composition with trans ‐nerolidol as the main constituent (72.5%), followed by γ ‐eudesmol (6.0%), trans ‐valerenyl acetate (5.9%), dihydroagarofuran (4.7%), and cis ‐lanceol (4.5%). Antimicrobial activity determined by the disc diffusion method showed moderate inhibition zones ranging from 9.33 to 13.67 mm against reference bacterial strains, with higher susceptibility observed in Gram‐positive species ( Enterococcus faecalis , Staphylococcus aureus , and Listeria monocytogenes ). MIC 50 values ranged from 0.051 ( E. faecalis ) to 6.372 mg/mL ( Candida tropicalis ). In situ antimicrobial activity in the vapor phase was confirmed on apple, strawberry, carrot, and celery models, with inhibition reaching up to 97% at 500 μ L/L. In a storage experiment with lettuce, the most effective treatment was the combination of HEO application and vacuum packaging, which reduced the total viable count from 4.03 (control) to 2.75 log CFU/g after 14 days of storage at 4°C. Identification of isolates from lettuce using MALDI‐TOF MS ( n = 314) revealed a microbiota dominated by Gram‐negative bacteria, with the genus Pseudomonas representing 47% of isolates (eight identified species). Fumigation assays against Callosobruchus maculatus and Megabruchidius dorsalis confirmed concentration‐dependent insecticidal activity. The results indicate that trans ‐nerolidol–rich HEO exhibited antimicrobial and insecticidal activity under the tested experimental conditions and may have potential for applications related to food preservation and protection against storage pests.

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