Research eradicates bacteria from avocado facility

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Dr Amy Strydom, postdoctoral fellow in the Department of Microbial Biochemical and Food Biotechnology at the University of the Free State (UFS). Photo: Supplied

Postdoctoral fellow in the Department of Microbial Biochemical and Food Biotechnology at the University of the Free State (UFS), Amy Strydom, has made an amazing breakthrough by eradicating bacteria at an avocado facility.

“The aim of my project was to identify and characterise the contamination problem in an avocado-processing facility and then to find a solution,” said Strydom.

Her PhD, “Control of Listeria monocytogenes in an Avocado-processing Facility”, aimed to identify and characterise the contamination problem in a facility where avocados were processed into guacamole.

Strydom completed her MSc in food science in 2009 at Stellenbosch University and this was the catalyst for her starting her PhD in microbiology in 2012 at the UFS. The research was conducted over a period of four years and she graduated in 2016. The research project was funded by the National Research Foundation (NRF).

The opportunity to work closely with the food industry further motivated Strydom to conduct her research. The research has made a significant contribution to a food producer (avocado facility) that will sell products that are not contaminated with any pathogens.

The public will then buy food that is safe for human consumption. Listeria monocytogenes is a food-borne pathogenic bacterium. When a food product is contaminated with L. monocytogenes, it will not be altered in ways that are obvious to the consumer, such as taste and smell.

Strydom worked closely with the facility and developed an in-house monitoring system by means of which the facility could test their products and the processing environment. She also evaluated bacteriophages as a biological control agent in the processing facility. Bacteriophages are viruses that can only infect specific strains of bacteria.

She found that only 26% of the L. monocytogenes population in the facility was destroyed by the ListexP100TM product.

“I concluded that the genetic diversity of the bacteria in the facility was too high and that the bacteriophages could not be used as a control measure. However, there is much we do not understand about bacteriophages, and with a few adjustments, we might be able to use them in the food industry,” she added.

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