A Halochromic Film Containing Plinia cauliflora Peel Anthocyanins Loaded into a Cashew Gum Polysaccharide-Polyvinyl Alcohol Matrix

This study reports the extraction of anthocyanins from P. cauliflora peels, its partial characterization and the inclusion into a halochromic film based on cashew gum polysaccharide and polyvinyl alcohol (CGP/PVA). Three kinds of extractions were performed: The classic acidic-alcoholic solvent method; enzymatic method with the cell wall degrading enzymes (cellulase and pectinase) and the combination of these two extraction methods. Time and temperature for extraction varied from 3, 6, 9, 12, and 24 h and 4, 20, 30, and 40 °C, respectively. After extraction, the anthocyanins were fractionated by chromatography and partially characterized by Fourrier transform infrared spectroscopy (FTIR) and regarding their antioxidant activity. Maximum values found in the extraction procedures were 368 ± 1.94 mg 100 g −1 (30 °C/9 h); 216.76 ± 2.98 mg 100 g −1 (40 °C/3 h) and 707.09 ± 3.97 mg 100 g −1 , respectively for acidic-alcoholic solvent, for cellulase and for a combination of solvent and enzyme extraction. The antioxidant activity of the anthocyanins was preserved, showing higher values than the commercial antioxidant BHT. The chromatographic fractionation resulted in 2 peaks, which presented characteristic bands of cyanidin 3-glucoside and delphinidin in FTIR. The inclusion of anthocyanins in CGP/PVA films resulted in a pH-sensitive material changing the color from clear red in acid pH environment to brownish-green color in basic medium. The results of this study were promising and indicate that CGP/PVA-anthocyanin films are good candidates for smart packaging development. Graphical Abstract