The present study evaluates the optical and colorimetric properties of Polylactic acid (PLA)-based films blended with Poly(3-hydroxybutyrate) (PHB) and Poly(butylene succinate) (PBS) and impregnated with mango leaf extract (MLE) using supercritical solvent impregnation (SSI) under different operating conditions (pressure: 10–30 MPa; temperature: 35–55 °C). Additionally, the relationship between impregnation load (IL) and color properties, as well as the release kinetics of the impregnated compounds, was investigated. The incorporation of PHB and PBS into the PLA matrix prior to impregnation led to a slight increase in the b* parameter (from 1.64 to 2.61), indicating a tendency toward yellowish tones. After SSI, all films exhibited noticeable color changes, with a shift toward yellowish-green hues and a decrease in lightness, regardless of processing conditions. Statistical analysis confirmed that polymer composition and its interaction with pressure and temperature significantly affected color properties (p-value 85%, p-value 0.90). Furthermore, Korsmeyer–Peppas model fitting yielded diffusion exponents (n < 0.5), indicating quasi-Fickian diffusion mechanisms governing the release process.
León-Marcos et al. (Mon,) studied this question.