Elite Herb Extracts Containing High Rosmarinic Acid and Inhibition of Listeria monocytogenes in Meat and Poultry Products

This study investigated herbal extracts high in rosmarinic acid (rosemary antioxidants) as Listeria monocytogenes inhibitors.

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Objectives

To evaluate the effectiveness of high rosmarinic acid-containing herb extracts to inhibit L. monocytogenes in laboratory media; and to evaluate the effectiveness of high rosmarinic acid-containing herb extracts in ready to eat meat and poultry products.

Conclusions

The high-phenolic producing UMass clonal line of oregano was able to significantly inhibit the growth of the pathogen that was inoculated into the broth system at varying levels. Two of the main constituents of the oregano, thymol and carvacrol, also displayed a very powerful inhibition of the pathogen. When the extract was applied to a meat system that was contaminated with L. monocytogenes, results showed that the oregano extract was effective at concentrations of at least 800 ppm on the meat. In addition, the meat studies also indicate that the entire oregano extract is more effective at inhibiting the growth of the pathogen than just the phenolic by itself. Studies done comparing the effectiveness of the UMass clonal oregano against the store brands provided inconclusive results. Although the UMass clonal line was slightly better than the store brands when equivalent amounts of the extracts were tested, the UMass clonal line did not perform better than the store brands when compared on an equal phenolic basis. The studies used ethanol extracts of oregano. This extract provided high amounts of antimicrobial activity and can be very well utilized in a food matrix. This is because the phenolics in this extract can work at an interface of both lipid and water-soluble components in the food.

Deliverable

This study indicates that oregano extract has antilisterial properties in a model meat system; however, relatively high concentrations of the ingredient were needed to show efficacy.