Non-pathogenic Listeria, Bacillus cereus, and Staphylococcus aureus have been detected in plant-based products tested in Switzerland. The study, published in the Journal of Food Protection , assessed the microbiological quality and occurrence of some foodborne pathogens in plant-based meat alternatives from Swiss retailers. Plant-based meat alternative products have a high water activity, high nutrient content, and only slightly acidic pH, making them susceptible to microbial spoilage.
These items have specific processing steps, such as extrusion or cooking, and use raw materials such as soy, wheat, or pea proteins. In December 2023, 100 plant-based meat alternatives were randomly collected from five major retail stores. A total of 84 vegan and 16 vegetarian products from 27 brands were analyzed qualitatively for the presence of Salmonella and Listeria monocytogenes and quantitatively for Staphylococcus aureus, Bacillus cereus, Enterobacteriaceae, and total viable count.
Also, pH measurements were carried out, and the water activity value was determined. No Salmonella or Listeria monocytogenes were detected. However, seven products were contaminated with other Listeria species.
Selected results Six of the seven Listeria isolates were Listeria innocua, while the other was Listeria seleri. This finding shows that Listeria species can occur in such products. Researchers said their presence shows that Listeria monocytogenes cannot be ruled out and should be examined with a larger.