Validating the inhibition of Staphylococcus aureus in shelf-stable, ready-to-eat snack sausages with varying combinations of pH and water activity

Abstract

Shelf-stable, ready-to-eat meat and poultry products represent a large sector of the meat snack category in the meat and poultry industry. Determining the physiochemical conditions that prevent the growth of foodborne pathogens, namely, Staphylococcus aureus postprocessing, is not entirely clear. Until recently, pH and water activity (aw) criteria for shelf stability has been supported from the U.S. Department of Agriculture training materials. However, concern about the source and scientific validity of these critical parameters has brought their use into question. Therefore, the objective of this study was to evaluate different combinations of pH and aw that could be used for establishing scientifically supported shelf stability criteria defined as preventing S. aureus growth postprocessing. Snack sausages were manufactured with varying pH (5.6, 5.1, and 4.7) and aw (0.96, 0.92, and 0.88) to achieve a total of nine treatments. The treatments were inoculated with a three-strain mixture of S. aureus, with populations measured at days 0, 7, 14, and 28 during 21°C storage. Results revealed treatments with a pH ≤ 5.1 and aw ≤ 0.96 did not support the growth of S. aureus and thus could be considered shelf stable for this pathogen. The results provide validated shelf stability parameters to inhibit growth of S. aureus in meat and poultry products.