Smart pH‐Sensitive Indicator Films Based on Gellan Gum/Starch/Xanthan Gum With Aronia Extract: Real‐Time Tracking of Chicken Freshness

The market for intelligent freshness indicator packaging made of bio‐based materials that are also environmentally friendly has grown significantly in recent times. In this study, aronia (AR) anthocyanins were integrated into gellan gum (GG), starch (ST) and xanthan gum (XG) matrices, which can be applied in smart food packaging. The successful interaction of different AR anthocyanin concentrations with the polymer matrix was supported by Fourier transform infrared spectroscopy (FTIR), X‐ray diffractometry (XRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The inclusion of AR increased the films' thickness, total colour difference (Δ E ) values, mechanical characteristics and opacity; additionally, water vapour permeability and moisture content decreased. The total antioxidant capacity, total monomeric anthocyanin contents and antibacterial activity test results of the GSX‐AR films rose and were positively associated with the quantity of AR. The quality of skinless boneless chicken breast flesh was monitored with GSX‐AR3 film containing 35‐mg AR extract and significant colour changes in different buffer solutions, and high sensitivity in ammonia solutions of different concentrations was noted. During the chicken freshness test, the change of colour of GSX‐AR3 films and thereby the changes in Δ E values agreed well with the total volatile basic nitrogen (TVB‐N) content and microbial growth in chicken samples, reaching the total viable count (TVC) of 6.73 log CFU/g and TVB‐N of 30.79 mg N/100 g during 7 days of refrigerated storage. As a crucial freshness indicator, the films' sensitivity to ammonia was demonstrated by their obvious colour and visually distinguishable shift from pinkish‐red to yellowish‐green when exposed to the gas released as they deteriorated. The proposed intelligent indicator can be used to detect the freshness of foods with high protein content. The biodegradable and pH sensitive GSX‐AR3 film has the potential to be applied in smart food packaging.