Garlic, Onion, and Cinnamon Essential Oil Anti-biofilms' Effect against Listeria monocytogenes.

Mariem Somrani,María-Carmen Inglés,Ferid Abidi,Hajer Debbabi,Alfredo Palop

doi:10.3390/foods9050567

Abstract

Biofilms represent a serious problem for food industries due to their persistence in processing surfaces, from which they can cause food spoilage or, even worse, lead to foodborne diseases. Microorganisms immersed in biofilms are more resistant to biocides. The search for natural effective alternatives for the prevention and the control of biofilms has increased lately. The aim of this research was to test the antibacterial and the anti-biofilm activities of cinnamon, onion, and garlic essential oils against Listeria monocytogenes. The methodology highlighted first the effect of these essential oils on L. monocytogenes using disc diffusion and minimum inhibitory concentration (MIC) methods and then on initial cell attachment and six hours preformed biofilms. The inhibition of biofilms was assessed by crystal violet assay. Sulfides were the most abundant compounds present in onion and garlic essential oils, while cinnamaldehyde was predominant in cinnamon essential oil. MIC values were of 0.025 mg mL−1 for onion essential oil and 0.100 mg mL−1 for cinnamon and garlic. Onion essential oil inhibited initial cell attachment by 77% at 0.5 of the MIC dose, while at MIC, cinnamon and garlic essential oils inhibited the initial microbial adhesion completely. All three essential oils completely inhibited initial cell attachment when applied at 2 MIC. On the contrary, preformed biofilms were more resistant, and the inhibition rate ranged from 33% to 78%. In summary, this investigation revealed that the essential oils of garlic, onion, and cinnamon show an effective antibiofilm activity against L. monocytogenes and are promising natural antimicrobial alternatives for food processing facilities.

Highlights

Listeria monocytogenes is a Gram-positive bacterium that is commonly present in the environment as well as in food processing facilities, especially in inaccessible parts of industrial equipment and materials, where it can last up to 10 years [1]
This investigation revealed that the essential oils of garlic, onion, and cinnamon show an effective antibiofilm activity against L. monocytogenes and are promising natural antimicrobial alternatives for food processing facilities
The hazard of L. monocytogenes consists, in its ability to grow under refrigeration temperatures and in its ability to form biofilms, which are difficult to eliminate during the cleaning process [3,4,5]

Summary

Introduction

Listeria monocytogenes is a Gram-positive bacterium that is commonly present in the environment as well as in food processing facilities, especially in inaccessible parts of industrial equipment and materials, where it can last up to 10 years [1]. Listeriosis is a disease that predominantly affects immunocompromised persons, such as the elderly, immunosuppressed people, and pregnant women, together with their unborn or new-born babies. It is of particular concern because of its high mortality rate. The hazard of L. monocytogenes consists, in its ability to grow under refrigeration temperatures and in its ability to form biofilms, which are difficult to eliminate during the cleaning process [3,4,5]

Objectives

Methods

Discussion

Conclusion