Development of edible films containing Psyllium (Plantago ovata) mucilage and probiotics and their application on apple slices

In this study, edible films based on sodium caseinate and enriched with the probiotic Lacticaseibacillus rhamnosus GG were formulated using psyllium mucilage powder (PMP; 0%, 0.25%, 0.50%, and 0.75%). The films were analyzed for physicochemical, barrier, color, optical, mechanical, and structural properties, including probiotic viability. Additionally, fresh apple slices were coated with the selected probiotic film solution (0.25% PMP) and stored at 4 ± 1 °C for 12 days. During the storage period, changes in weight loss, total soluble solids, color parameters, and probiotic viability of the apple slices were monitored. The addition of PMP significantly enhanced the drying and storage stability of probiotics (p < 0.05). PMP incorporation also had a statistically significant impact (p < 0.05) on physical properties such as film thickness, dry matter density, water solubility, and tensile strength. Additionally, PMP improved the microstructural integrity of the films. The coating process effectively minimized weight loss in fresh apple slices and maintained sufficient probiotic viability throughout the storage period. However, the browning index of the coated apple slices was higher compared to the uncoated control samples. The results demonstrate that sodium caseinate-based polymeric matrices containing PMP are suitable carriers for Lacticaseibacillus rhamnosus GG and and fresh apple slices coated with these films have the potential to be evaluated as a probiotic product.