Antimicrobial efficacy of nisin, oregano and ultrasound against pathogens on lettuce

By Brian Takundwa

Researchers in South Africa set out to harness the individual efficacy of nisin, oregano and ultrasound into a more robust combined antimicrobial treatment against pathogenic bacteria, Escherichia coli O157:H7 and Listeria monocytogenes.

Shifts in dietary trends, in the last two decades, have encouraged an increase in the global consumption of fresh produce.  Concurrently, there has also been a relative increase in foodborne illnesses linked to fresh produce consumption. As a result, various decontamination methods are being used, the most common being, thermal and chlorination techniques. However, the appeal to use non-chemical and non-thermal methods to decontaminate and preserve the properties of fresh produce has been gaining traction. This study therefore investigated the efficacy of a combination of nisin, oregano and ultrasound on the reduction of E. coli O157:H7 and L. monocytogenes on lettuce.

The combined treatments were able to show impressive synergistic effects against both pathogens on inoculated lettuce. The inactivation levels on L. monocytogenes were even more remarkable, with high log reduction values recorded. Further tests on the physical quality of lettuce after treatment was also conducted, with only minimal effects observed. This study was able to exhibit the huge potential in combining natural antimicrobials as alternative and adequate decontamination measures.

For further reading kindly check the link below:

Takundwa, B. A., Bhagwat, P., Pillai, S. & Ijabadeniyi, O. A. 2020. Antimicrobial efficacy of nisin, oregano and ultrasound against Escherichia coli O157: H7 and Listeria monocytogenes on lettuce. LWTFood Science and Technology, 110522. https://doi.org/10.1016/j.lwt.2020.110522