Biodegradable Colorimetric Indicative Films Based on Kurugua (Sicana odorifera) Peel Powder

Colorimetric films are helpful as indicators of the freshness of foods, changing color as their pH varies as they undergo decomposition reactions. Anthocyanins are an important group of bioactive compounds whose color varies depending on the pH of the medium, which is why they are used in this type of film. This work evaluated colorimetric indicator films based on the cassava starch and anthocyanins present in kurugua (<i>Sicana odorifera</i>) peel powder. The total anthocyanin content in the kurugua peel powder was quantified (12.13 ± 0.48 mgC3G/L of extract). Films were prepared by casting, based on starch without (PC) and with the addition of kurugua shell powder in low (PB) and high (PA) proportions. Adding kurugua peel powder affected the properties of the films, such as their thickness (0.08 to 0.13 mm), solubility (15 to 18%), humidity (21 to 23%), water contact angle (31 to 61°), density (0.17 to 0.33 g/cm³), and opacity (2.73 to 7.74 A600 nm/mm). Raman spectra showed characteristic peaks for starch and anthocyanins. Finally, the color change capacity of the colorimetric indicator films (PA and PB) was demonstrated, changing to green and yellow colorations at high pH values, as well as during their application in monitoring the freshness of chicken meat; thus, their suitability for use as active and intelligent indicators in the food industry was confirmed.