Incorporating probiotic bacteria with different biopolymers as edible films is an effective approach to improve their viability. In this study, three different films (wheat sourdough powder, whole wheat flour, and bovine bone gelatin) are incorporated with Lactobacillus plantarum separately and the viability of bacteria is monitored during the storage time (40 days at 4 °C) and simulated gastrointestinal conditions. The results demonstrated that the sourdough film has the best protective effect on the viability of the cells during the film’s preparation, storage time (6.5 Log/CFU/g), and simulated gastrointestinal conditions (7.13 Log/CFU/g). A higher rate of reduction is observed in gelatin film at the end of the storage time (4.03 Log/CFU/g). Physicochemical, and mechanical characteristics are examined. It is observed that the incorporation of bacteria does not affect the thickness, moisture content, and solubility of all films, but changed the mechanical properties of the sourdough and the wheat flour films (p ≤ 0.05). Scanning Electron Microscope images showed a more uniform and compact structure for both bacterial and control gelatin films. Although the sourdough film is appropriate for protecting probiotic bacteria (>106 CFU/g), further studies are needed to improve its mechanical properties.

Keywords