Effects of thyme essential oil and verbenone against Listeria on fresh-cut fruit

Researchers at the University of Limerick studied the effectiveness of thyme essential oil and other compounds - camphor and verbenone -against Listeria on fresh-cut products such as lettuce, Cantaloupe melon and pineapple. These were packaged in a modified atmosphere and stored at 4 and 8°C.

It was discovered that Listeria monocytogenes can survive in all atmospheres on melon and lettuce, while it seems the pathogen was reduced on pineapple, maybe due to its pH level.

Thyme essential oil was the most effective, especially if applied directly on the fruit compared to dipping. It however compromised the aspect of the fruit.

As regards lettuce, the treatment was unsuitable because it damaged the aspect of the product.

Camphor showed no effects against Listeria, while verbenone had an effect and maintained the characteristics of the fruit.

The application of verbenone significantly reduced the microbial load of L. monocytogenes on the melon and eliminated it on the pineapple.

Dipping in thyme essential oil and verbenone had positive results for both melon and pineapple, however it must be said that, when compared to dipping in chlorinated water, load reduction was less pronounced in the melon.

Researchers have concluded that further studies are necessary to improve the treatment of fresh-cut produce with natural substances before they can replace the current chlorine treatments and improve food security.

Source: Scollard J., McManamon O., Schmalenberger A., 'Inhibition of Listeria monocytogenes growth on fresh-cut produce with thyme essential oil and essential oil compound verbenone', October 2016, Postharvest Biology and Technology, Vol. 120, pagg. 61-68. www.sciencedirect.com/science/article/pii/S0925521416300953

Contacts:
A. Schmalenberger
University of Limerick, Department of Life Sciences
Limerick, Ireland
Email: achim.schmalenberger@ul.ie

Author: Emanuela Fontana
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