Probiotic Edible Films Supplemented with Psyllium (Plantago ovata) Mucilage Containing Lacticaseibacillus rhamnosus GG: Coating for Fresh Apple Slices

Abstract

Sodium caseinate-based edible film containing probiotic Lacticaseibacillus rhamnosus GG was supplemented with psyllium mucilage powder (PMP; %0, %0.25, %0.50, and %0.75). The obtained films were examined for physicochemical, optical, mechanical, and structural properties, as well as probiotic viability. Moreover, a probiotic film solution (0.25% PMP, the most suitable film formulation) was applied to coat fresh apple slices, and the samples were evaluated for weight loss, total soluble solids content, color properties, and probiotic viability during storage (12 days at 4 °C). The addition of PMP had a significant (p < 0.05) effect on the drying process and storage stability of the probiotic. The effect of PMP incorporation on the thickness, density, water solubility, and tensile strength values of the films was significant (p < 0.05). The increase in PMP concentration resulted in a reduction in the number of pores on the surface of the film and the formation of a more homogeneous film cross-section. Although the coating process limited weight loss in fresh apple slices, the browning index (BI) of coated apples was higher. At the end of storage, the BI value of the coated apple slices was 55.89 ± 3.82, while the BI value of the control sample was 30.64 ± 2.85. Moreover, the coated apple slices contained sufficient levels of probiotics (6 Log CFU g⁻1) at the end of storage. The results showed that sodium caseinate-based film matrices containing PMP were suitable carriers for L. rhamnosus GG and fresh apple slices coated with a film solution containing 0.25% PMP could be considered a probiotic product.