A new approach to obtain chitosan films – Characteristics of films prepared with tea and coffee kombucha as natural chitosan solvents

The environmental degradation that is currently taking place makes it important to develop new natural and biodegradable packaging for various branches of industry. Therefore, the aim of the research was to characterize films prepared from chitosan and kombucha solutions obtained from coffee and three types of tea (black, green, and white). Kombucha solutions were used as a natural solvent for the preparation of chitosan films which is a new approach in the production of chitosan films and has not been used so far. Both the kombucha and chitosan-kombucha solutions were characterized by high antioxidant activity in the DPPH test. This could be connected with the presence of phenolic compounds in kombucha solutions, which were determined by ultra-high performance liquid chromatography. In turn, chitosan-kombucha films had different physical, mechanical and biological properties depending on the type of kombucha solutions used. The highest oxygen barrier was determined for the film obtained from chitosan and green tea kombucha solution. The film consisting of chitosan and white tea kombucha solution was characterized by the highest tensile strength. In turn, microbiological studies showed that films based on chitosan and tea kombucha solutions showed higher activity against Salmonella eneterica than kombucha solutions, while film that consisted of a chitosan and black tea kombucha solution additionaly exhibited greater activity against Escherichia coli. Moreover, the analysis of sorption showed that kombucha solutions limited the accessibility of primary sorption sites. The results indicated that the type of kombucha used to prepared chitosan-kombucha films affects the properties of the obtained films. In addition, kombucha solutions can be used as a natural chitosan solvent instead of inorganic acids. The results of the study confirmed that chitosan films produced using kombucha as a solvent are better than the chitosan films commonly produced with acetic acid, so they can be a viable alternative material for food packaging.