Study - Growth and Survival of Vegetative Pathogens in Beef and Plant (Fake Beef) Burgers

Not that we would expect to have high levels of vegetative pathogens (STEC, E. coli, Listeria, and Salmonella) in plant-based burgers, but we would consider the risk of them being there should be low, with the possible exception of Listeria.  However, the plant-based burgers are a TCS food (they have the necessary nutrients, Aw and pH) and thus will support the growth of organisms during storage. 

Storage at refrigeration and slight temperature abuse situations - At slight temperature abuse temperatures (10C), the levels of all three pathogens increased by ca. 1.0 to ca. 2.5 log CFU/g in plant-based burgers (beef burgers showed a slight decrease).
Cooking - all pathogens were reduced equally well in plant-based burgers and regular burgers.

Key - need to treat plant based burgers like regular burgers, especially regarding storage temperatures.

Viability of Shiga Toxin–Producing Escherichia coli, Salmonella, and Listeria monocytogenes within Plant versus Beef Burgers during Cold Storage and following Pan Frying 
JOHN B. LUCHANSKY ;  BRADLEY A. SHOYER  ;  YANGJIN JUNG  ;  LAURA E. SHANE  ;  MANUELA OSORIA  ;  ANNA C. S. PORTO-FETT
J Food Prot (2020) 83 (3): 434–442.
https://doi.org/10.4315/0362-028X.JFP-19-449

ABSTRACT

The viability of Shiga toxin–producing Escherichia coli (STEC), Salmonella, and Listeria monocytogenes within plant- and beef-based burgers was monitored during storage and cooking. When inoculated (ca. 3.5 log CFU/g) into 15-g portions of plant- or beef-based burgers, levels of STEC and Salmonella decreased slightly (≤0.5-log decrease) in both types of burgers when stored at 4°C, but increased ca. 2.4 and 0.8 log CFU/g, respectively, in plant-based burgers but not beef-based burgers (≤1.2-log decrease), after 21 days at 10°C. For L. monocytogenes, levels increased by ca. 1.3 and 2.6 log CFU/g in plant burgers after 21 days at 4 and 10°C, respectively, whereas pathogen levels decreased slightly (≤0.9-log decrease) in beef burgers during storage at 4 and 10°C. Regarding cooking, burgers (ca. 114 g each) were inoculated with ca. 7.0 log CFU/g STEC, Salmonella, or L. monocytogenes and cooked in a sauté pan. Cooking plant- or beef-based burgers to 62.8°C (145°F), 68.3°C (155°F), or 73.9°C (165°F) delivered reductions ranging from ca. 4.7 to 6.8 log CFU/g for STEC, ca. 4.4 to 7.0 log CFU/g for L. monocytogenes, and ca. 3.5 to 6.7 log CFU/g for Salmonella. In summary, the observation that levels of all three pathogens increased by ca. 1.0 to ca. 2.5 log CFU/g in plant-based burgers when stored at an abusive temperature (10°C) highlights the importance of proper storage (4°C) to lessen risk. However, because all three pathogens responded similarly to heat in plant-based as in beef-based burgers, well-established cooking parameters required to eliminate STEC, Salmonella, or L. monocytogenes from ground beef should be as effective for controlling cells of these same pathogens in a burger made with plant-sourced protein.