In a context of increasing the world’s population and resources consumption one of the greatest challenges of our society is to produce innovative materials by valorization of the renewable resources with the attempt to diminish the dependency of European companies on petroleum-based plastics. The aim of the paper is to develop bioformulations based on the revalorization of casein as a source of protein material. Boric acid was used to produce cross-linked casein, gelatin and casein–gelatin blend (with the contents of casein in the range of 0 to 30 wt% with respect to gelatin) edible films with adequate properties to ensure the safety and preservation of food by inhibiting pathogenic microorganisms and generating zero waste after consumption. The aqueous solutions of gelatin and casein were prepared by dissolving in distilled water, in concentrations of 10% and 7.5%, respectively (weight percent). The gelatin was hydrated with distilled water at room temperature and then dissolved in a water bath at 55 °C for 30 min. The casein was dispersed in distilled water at room temperature, after which sodium hydroxide (NaOH) were added under constant magnetic stirring until pH 7.0 was reached. Zetasizer was used to analyse the particle dimension of casein. Morphology by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, water absorption and rheology were used to explain the interaction between gelatin and casein. Water absorption is dependent on the composition of the samples and the immersion time. The introdution of casein into edible food formulations does not lead to a decrease in the transmittance. Smooth structured films were obtained due to casein, which is a poorly organized protein. Rheological properties of casein-gelatin wetted films showed that the addition of casein significantly enhanced them. Further study needs to be done to elucidate the mechanism of increase in rate of storage modulus during the annealing stage.
Acknowledgement: This work was supported by a grant of the Romanian Ministry of Education and Research, CCCDI - UEFISCDI, project number PN-III-P2-2.1-PED-2019-2878, within PNCDI III” (BioMatFood), under the Contract No 379PED/2020.
- It is possible to open up new markets and increase demand for sustainable bio-waste products.
- Packaging of edible foods will improve consumer satisfaction.
- Environmental sustainability will be improved through a circular approach, water consumption and CO2 emissions in manufacturing processes will be reduced.