Evaluation of blueberry residue incorporated cassava starch film as pH indicator in different simulants and foodstuffs

Abstract Cassava starch, glycerol, blueberry residue (obtained from juice processing) and distillated water were used to develop biodegradable and intelligent films as an alternative to synthetic plastic non-biodegradable films from fossil sources. The color difference of this indicator was evaluated after its application in buffer solutions (pH = 4, 5, 6 and 7), simulants (saline, sucrose and protein solutions) and foodstuffs (orange juice, corn oil and chicken pieces). Color parameters were measured using the CIELAB color space. For all samples immersed in different buffer solutions, color changes were visually perceptible to the human eye since the color difference, ΔE*ab value, was higher than 5. In addition, it was possible to establish a correlation between the color of the samples after submersion in buffer solutions with different pH values, simulants as well as food product. The films containing blueberry residue powder with a lower particle size (FC100) displayed color changing properties and mechanical characteristics more uniform and homogeneous than the films containing blueberry residue powder with a higher particle size (FCG). The results showed the potential use of the developed biodegradable packaging containing agro-industrial residue as a pH indicator.