Comparison of Two pH Responsive Color Changing Bio-Based Films Containing Wasted Fruit Pomace as a Source of Colorants.

The main objective of this work is to develop and characterize novel bio-based sensor as intelligent food packaging film to monitor quality changes in fresh chicken meat. Chitosan (CS) and carboxymethyl cellulose (CMC) were used as polymer matrices for immobilization of pH sensitive color indicators. Generally considered as a food waste, blueberry (BP) and red grape skin pomace (RP) extracts were used as indicators at total phenolic content (TPC) of 0.06, 0.13, and 0.25 w/v for BP, and 0.006, 0.012, and 0.02 w/v for RP-based films. Color, mechanical, and intelligent material properties were determined. CS films were more elastic than CMC, while no significant changes in mechanical properties occurred after the addition of both extracts at all concentrations. Notable and eye recognizable color changes in dry films were seen. It was the most significant in the pH range from 4 to 7. For CMC-based films, color changed from violet to pink for BP extracts and from red to pink for RP extracts. For CS films, the changes were less significant. The color taint and intensity changed toward green in blueberry-based films and to orange in grape seed extract-based films. Significant color changes were observed after 46 hr in application tests on fresh chicken meat. This was correlated to pH changes of meat above 6 that was one of the parameters considered as an indication of spoilage. PRACTICAL APPLICATION: This work provides interesting data to food industry. It offers an idea and possibility of managing food waste from fruits and vegetables industry that makes problems and costs when needed to be disposed in a proper manner. Moreover, there is the possibility of producing novel kind of food packaging materials that could be used in order to check the end of food shelf-life in an inexpensive and natural way. Additional value lies in the fact that materials and procedures could be considered as sustainable.
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