Improving functional properties of PVA/starch-based films as active and intelligent food packaging by incorporating propolis and anthocyanin

An active and intelligent starch-based biodegradable food packaging system is developed in this work. The growing environmental protection concerns have motivated researchers to look for biodegradable yet sustainable products for food packaging. The packaging is able to resist against undesirable bacterial attack and color-change response due to pH change in food. Polyvinyl alcohol and starch are cross-linked with Glutaraldehyde to improve their mechanical strength. Propolis Extract (PE) and anthocyanin (ATH) were added as an active and intelligent material, respectively. Different film formulations were prepared by varying concentration of PE. All film formulations were characterized by SEM, FTIR and XRD. The results proved good compatibility of the film mixture. The mechanical strength and other physical properties like water vapor transmission rate, moisture retention capability, swelling degree and biological leaching ability were investigated. Films containing 20% PE showed the best results alongside maximum mechanical strength of 15.9 MPa. Furthermore, the same formulation has shown maximum zone of inhibition of 25 mm and 20 mm against E. Coli and MRSA, respectively. Moreover, there was a clear color-change response when films were immersed in different pH solutions ranging from 1 to 14. Finally, to validate the potential application of prepared film formulations, films were tested on pasteurized milk and a color-change response is observed along with the anti-bacterial activity. Hence, this active and intelligent food packaging system is capable of inhibiting and alerting food spoilage.