The effect of Pulsed Light and starch films with antimicrobials on Listeria innocua and the quality of sliced cheddar cheese during refrigerated storage

Abstract

The main goal of this study was to evaluate the effectiveness of a combination of antimicrobial films and Pulsed Light (PL) on inactivation of Listeria innocua on Cheddar cheese surface, and maintaining of product quality during refrigerated storage. The properties of antimicrobial starch films (ASF) containing sodium benzoate (ASF-SB), citric acid (ASF-CA), and both (ASF-CASB), prepared by casting and irradiated with PL, were evaluated. These films were used as packaging for Cheddar cheese slices that were surface inoculated with L. innocua at an initial inoculum level of 7 log CFU per cheese slice. PL had no effects on the structure of ASF. PL applied in combination with ASF-CA achieved an average of 4.5 log CFU reduction of L. innocua after 3 days of storage at 4 °C. However, significant changes in physicochemical properties of cheese, including pH, moisture level and mechanical properties, were observed after 7 days of refrigerated storage. These results suggest that, while PL-ASF can be effective in reducing L. innocua on Cheddar cheese surface, this combination treatment may induce some quality changes in the product.