Pectin Based Colorimetric Film for Monitoring Food Freshness

Abstract

The colours of anthocyanins are sensitive to variations in the pH of the environment. The field of food engineering is seeing a rise in the utilisation of anthocyanins obtained from plants to produce new and active packaging film. A pH-sensitive colorimetric film was developed using anthocyanin recovered from the peel of Phaseolus vulgaris (dark red kidney bean) in conjunction with composite pectin derived from citron peel. Additionally, Anthocyanins could be employed as colorimetric markers to identify food degradation, due to their sensitivity towards pH alterations and the production of ammonia gas. Solvent casting process was used to produce the film which changed from pink to brownish with rising pH due to the ammonia vapour that was produced. The antioxidant and antibacterial abilities of the anthocyanin containing smart films were investigated, and both Escherichia coli and Staphylococcus aureus growth was successfully inhibited. The developed film was characterized for its physical properties such as water solubility, moisture content and swelling index. To examine the structure of the films' surface, scanning electron microscopy (SEM) investigation has been carried out. The film indicator active response to pH fluctuation was demonstrated through tests on samples of chicken meat under various settings, allowing for the real-time monitoring of spoiled foods. This makes monitoring perishable goods, easy, affordable, environmentally friendly and biodegradable pH-sensitive indicator with visible colour change.