Effect of Potassium Lactate on Clostridium perfringens Growth during Extended Cooling of Uncured Turkey Breasts

Introduction: The Food Safety and Inspection Service (FSIS) of USDA has issued cooling guidelines under a directive known as Appendix B which specify chilling time and temperature limits for cured and uncured cooked meat products. Sodium lactate and potassium lactate have long been known to inhibit Clostridium botulinum but limited studies on C. perfringens inhibition have been reported.

Purpose: To determine the inhibition of C. perfringens during extended cooling of uncured turkey breast supplemented with potassium lactate.

Methods: Three treatments of ground, skinless, boneless turkey breast were prepared with 0 (Control), 1 or 2% potassium lactate (KL, 60% syrup, w/w), and inoculated with a three-strain mixture of C. perfringens spores to yield 3 log CFU/g.  Individual 100-g portions were vacuum-packaged, cooked to 71.1 °C (160 °F) and transferred to programmable incubators to simulate linear cooling to 4 °C (40 °F) during a 10- or 12-hour cooling protocol. Triplicate samples were assay for populations of C. perfringens by plating serial dilutions on tryptose-sulfite-cycloserine at 0-time, end of cooling and at three intermediate intervals for each cooling profile. Each study was replicated three times. 

Results: In Control samples without antimicrobial, average populations of C. perfringens increased 3.5 and 4.7 log at the end of the 10- and 12-hour chilling protocol, respectively.  In contrast, the addition of 1% KL reduced growth to only a 2.0 and 2.8 log increase during the two chilling protocols, respectively, whereas 2% KL inhibited growth to less than a 0.6 log CFU/g increase under both cooling regimes.

Significance: This study confirmed that the addition of 2% potassium lactate will inhibit growth of C. perfringens and can be used as an alternative to sodium nitrite during extended cooling in uncured meats.