STRUCTURAL CHARACTERIZATION OF EDIBLE FILMS WITH INCORPORATED LACTIC ACID BACTERIA FROM DAIRY BY-PRODUCTS

Recent studies have demonstrated that edible films serve as an effective vehicle for delivering functional components such as probiotics and prebiotics. However, the incorporation of probiotic lactic acid bacteria (LAB) may alter the structural and functional properties of these films.

In this study, edible films formulated from liquid acid whey protein concentrate (LAWPC) or liquid acid whey permeate (LAWP), containing sugar beet pectin, Tween 80, sunflower oil, and glycerol, were enriched with Lacticaseibacillus paracasei and Lactobacillus helveticus (~7 log CFU/g). The films were evaluated for their physicomechanical attributes, including thickness, tensile strength, elongation at break, water solubility, moisture content, and water vapor permeability (WVP).

The plain LAWP film exhibited significantly higher moisture content (28%), reduced thickness (54%), and greater stretchability (70%) compared to the plain LAWPC film (p < 0.05). Incorporation of both L. paracasei and L. helveticus into LAWPC films significantly enhanced their stretchability and tensile strength (p < 0.05). Additionally, L. helveticus reduced the thickness of LAWPC films, while L. paracasei increased the solubility of LAWP films (p < 0.05). However, the film type and LAB strain used did not affect water solubility, with mean values of 69.41% for LAWPC films and 77.26% for LAWP films (p ≥ 0.05). No statistically significant differences were observed in WVP among the film samples, with an overall mean of 2.60 × 10⁻⁶ ± 1.03 × 10⁻⁷ (g/(m.s.Pa)) (p ≥ 0.05).

These findings indicate that the combination of dairy by-products and LAB in edible films has a positive effect on their physicomechanical properties. Moreover, embedding the bacteria in an edible hydrocolloid matrix provides an excellent way to integrate probiotics into food products.