The use of antimicrobial sachets in the packaging of organic wild rocket: Impact on microorganisms and sensory quality

• Eugenol, carvacrol and trans-anethole can be used in active packaging.
• Active compounds are released into the headspace from biodegradable sachets.
• The antimicrobial activities vary between in vitro and in vivo test systems.
• Natural antimicrobial compounds mask off-odors released by decaying wild rocket.
• The use of active packaging must be optimized on an industrial scale.

Natural plant extracts from herbs and spices are regarded as safe products for the control of microorganisms. The aim of this work was to study the effects of natural antimicrobial compounds on the quality of packaged fresh organic wild rocket (Diplotaxis tenuifolia L.). The effects of eugenol, carvacrol, trans-anethole, trans-cinnamaldehyde, and α-pinene were tested in vitro against rot and human pathogens. All of the compounds exhibited antimicrobial activity, except for α-pinene. The efficacy of the antimicrobial compounds to control microorganisms, leaf color, spoilage volatiles, such as dimethyl disulfide, and sensory quality was tested in two in vivo experiments with sachets: a lab-scale jar experiment and a commercial-scale packaging experiment. In the jar experiment, eugenol showed higher antimicrobial activity than carvacrol against aerobic bacteria. All of the jars contained dimethyl disulfide in the headspace, but the sulfurous rotten odor was only detected in the control and eugenol samples, demonstrating that carvacrol, trans-anethole, and trans-cinnamaldehyde could mask the unpleasant odor of rotten wild rocket. In the packaging experiment, there was no clear effect of eugenol, carvacrol or trans-anethole on the microbial load, but eugenol and trans-anethole masked the off-odor ratings of wild rocket. Evaluation of antimicrobial compounds for packaged fresh produce must include in vitro and in vivo testing because the benefits in real food systems may differ from those obtained in the laboratory.

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