Characterization of Dairy Industry Secondary Material-Based Edible Films: Effect of Incorporated Lactic Acid Bacteria

Abstract

Edible films are a promising method for delivering probiotics in food. The survival of Lacticaseibacillus paracasei A11 and Lactobacillus helveticus MI-LH13 (7 log CFU/g), which were cultivated in liquid whey permeate (LWP), in films made from liquid acid whey protein concentrate (M) or liquid acid whey permeate (Z), was evaluated over 21 days at 25 °C and 4 °C. Film drying and matrix type had varying effects on strain survival. In the Z film, L. helveticus did not survive drying, but L. paracasei did. Both strains increased in the M film during drying. During storage, survival was low at 25 °C, but at 4 °C, strains survived better, especially in the M film (4.76–6.12 log CFU/g). The plain Z film was 28% more moist, 54% thinner, 70% more stretchable, 43% less opaque, 10% whiter, 47% redder, 43% bluer, and 64% less viscous compared to the plain M film. Incorporating both strains into M films (M + L. p, M + L. h) increased lightness, stretchability, and tensile strength while reducing viscosity and opacity (p < 0.05). The inclusion of the L. helveticus strain in M films reduced their thickness, whereas the presence of L. paracasei in the Z film enhanced solubility. Both films supported strain survival without negatively affecting the films’ rheological, optical, physicomechanical, and morphological properties, demonstrating the potential of LAB-incorporated edible films for probiotics delivery, shedding light on their adaptations and interactions within the film matrix. Furthermore, the impact of drying and storage conditions on LAB survival provides valuable insights for optimizing the formulation and application of these films in the food industry.