Bioactive and pH-sensitive films based on carboxymethyl cellulose and blackberry (Morus nigra L.) anthocyanin-rich extract: A perspective coating material to improve the shelf life of cherry tomato (Solanum lycopersicum L. var. cerasiforme)

Abstract

Abstract This study aimed to produce an innovative antioxidant and pH-sensitive film packaging based on carboxymethyl cellulose (CMC) and incorporating different amounts of blackberry (Morus nigra L.) anthocyanin rich-extract. The films were characterized and applied as a coating in the postharvest conservation of cherry tomato (Solanum lycopersicum L. var. cerasiforme) to demonstrate the effectiveness for food conservation. The results obtained demonstrated that the films presented considerable good physicochemical parameters, especially a low water solubility (below 15%) and high UV-blocking property (transmittance below 0.8%). The films presented high content of phenolic compounds and anthocyanins, increasing according to the addition of blackberry extract in the film formulation. Moreover, the controlled release of the active compounds indicated a constant profile between 2 and 240 h, which suggests a promising behavior for food conservation. Based on the presence of anthocyanins, the films changed the color according to the pH exposed, and then, can be classified as pH-sensitive packaging. The CMC films demonstrated positive behavior in the postharvest conservation of cherry tomato for 15 days of storage, maintaining constant fruit weight and firmness. In the sensorial attributes, the concentration of anthocyanin-rich extract used for the film formulation significantly affected visual acceptance. Beyond, the highest concentrations of extract negatively affected the purchase intention of cherry tomatoes. In conclusion, the biodegradable CMC films can release bioactive-antioxidant compounds and increase the shelf life of cherry tomatoes, and therefore, may be considered as a new alternative to packaging in food systems.