Green plantain (Musa paradisiaca L.) starch modified by natural fermentation and calendula (Calendula officinalis L.) essential oil for biodegradable and sustainable bioplastics

Abstract

This study developed biodegradable films from native green plantain (Musa paradisiaca L.) starch, modified by natural fermentation, with different concentrations (0.2, 0.4, and 0.6%) of an emulsion of calendula (Calendula officinalis L.) extract. The starch modification and the corporation of the emulsion were evaluated with respect to the films' properties and biodegradability. Significant changes in pH, acidity, and amylose (37.52% to 31.33%) during fermentation were attributed to organic acid production. The addition of extract emulsion resulted in a decrease in water vapor permeability (89%) and significant differences in solubility (32.66%-16.47%). The mechanical analysis indicated a lower modulus of elasticity (39.30 MPa) at higher emulsion concentration, which influenced the maximum stress and deformation of the films. Scanning electron microscopy (SEM) showed coalescences in films with higher emulsion concentrations. The antioxidant capacity measured by the FRAP method showed a significant difference compared to the control (1.09%-1.94%), but the modified starches did not differ from each other. The addition of emulsion improved biodegradability, with treatment F0.6 showing the highest degradation. These results indicated that fermentation-induced starch modification, combined with the incorporation of calendula extract, influences the physicochemical, mechanical, and biodegradation properties of the films. Changes in barrier performance and biodegradability suggested potential applicability as sustainable materials for reducing plastic waste, particularly in applications requiring controlled degradation and functional activity.