The aim of this study was to assess the microbiological quality and occurrence of foodborne pathogens in plant-based meat alternative (PBMA) products collected at retail level in Switzerland. A total of 100 PBMA (84 vegan and 16 vegetarian products) were qualitatively analysed for the presence of Salmonella , Listeria monocytogenes and quantitatively for Staphylococcus aureus , members of the Bacillus cereus group , Enterobacteriaceae and total viable count. In addition, pH measurements were performed and the AW value was determined.
This study provides data that are relevant to the Hazard Analysis and Critical Control Point (HACCP) concepts of companies producing plant-based meat alternatives and helps define the microbiological parameters to be included when testing these products.
Isolates were analysed by whole genome sequencing. Total viable counts before the expiration date ranged from <2 log to 7 log CFU/g (mean: 5.97 log CFU/g). Enterobacteriaceae with 2 log to 3 log CFU/g were detected in six (6%) samples. Salmonella and Listeria monocytogenes were not detected . However, seven products (7%) were contaminated with other Listeria spp. (six L. inocua and one L. seeligeri ). Other findings included two (2%) Staphylococcus aureus ST8 with presence of selx and tsst-1 genes, and five (5%) members of the Bacillus cereus group (three B. paranthracis , one B. cereus sensu stricto and one B. cytotoxicus ) which were strains associated with diarrhoea.
Characteristics of plant-based meat alternative products, such as high water activity, high nutrient content, and high pH, make them susceptible to microbial spoilage. Therefore, these products must be kept refrigerated. Since the products in this study were purchased at the retail level, there was no control over their storage conditions prior to testing. This lack of control may have contributed to the variability of the microbial load, as inconsistent storage practices can affect microbial findings. The predominance of members of the lactic acid bacteria group in PBMA may be relevant to product stability.
PBMA products are usually subjected to a heating stage that would control contamination. However, unlike raw meat, heating does not result in a colour change of PBMA, which makes it sometimes difficult for the consumer to determine whether it has been sufficiently heated. In addition, consumers should be aware that compliance with basic hygiene measures to avoid cross-contamination is especially important when handling foods that are not ready to eat immediately. Increasing consumer awareness regarding food handling and storage is recommended.
FoodWorld 