Phage-activated edible biopackaging for Listeria monocytogenes control in cheese: in vitro and in vivo assessment of whey protein- and tapioca starch-based solutions

The growing demand for natural and sustainable food preservation strategies has driven the development of innovative edible biopackaging solutions. This study aimed to formulate and evaluate the role of two novel anti-Listeria edible bioactive packaging solutions, based on whey protein (WPS) and tapioca starch (TSS), both activated with the commercial bacteriophage Listex™ P100. Physical analyses revealed that WPS exhibited higher density (1.08 g/mL), lower surface tension (56.9 mN/m), and a higher negative zeta potential (−37.0 mV) compared to TSS (0.97 g/mL, 74.7 mN/m, −4.4 mV, respectively), indicating superior spreadability and electrostatic stability than TSS packaging. WPS films also demonstrated greater thickness (0.188 mm vs. 0.094 mm) and lower transparency (759.13 % vs. 233.56 %) than TSS films. Both formulations maintained microbiological safety and phage viability for up to 60 days under refrigerated conditions. In vivo trials, on artificially contaminated cheese samples, showed a significant reduction in Listeria monocytogenes counts [≈1.1 log colony forming units (CFU)/g] after 3 days of storage when treated with either WPS or TSS phage containing coatings, compared to untreated controls. From a sensory standpoint, mini cheeses coated with WPS were rated as having excellent overall quality, characterized by a typical appearance and absence of visual defects. These findings provide a preliminary proof-of-concept for the use of phage-activated edible coatings as a sustainable and safe strategy to improve cheese safety.