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The Pressurized Soaking Impregnation Method combines the main advantages of supercritical solvent impregnation and the soaking casting technique. This work studied the impregnation of poly(3-hydroxy-butyrate-co3-hydroxy-valerate) (PHB-HV) sheets with mango leaf extracts using this method for its future use as active packaging. The influence of temperature (35–55 ºC), pressure (10, 20–30 MPa), and depressurization rate (0.1–5 MPa/min) on the impregnation loads, antioxidant capacities, and mechanical properties of the impregnated samples were evaluated. In addition, the morphological characteristics, colour characterization, and release of active compounds in a food simulant of the PHB-HV samples impregnated at 30 MPa were analysed. The results showed higher impregnation loads (7.66 % wt.) at 30 MPa, 55 ºC, and a slow depressurization rate (0.1 MPa/min). However, the impregnation of antioxidant compounds did not show the expected behaviour, reaching values lower than 3 %. In addition, the samples that were impregnated at 30 MPa showed colour differences that were perceptible to the human eye. A non-homogeneous distribution of impregnation, cracks, and pores on the surface were also observed. The release study in the D1 food simulant showed good agreement with the Peleg model and a quasi-Fickian diffusion behaviour according to the Korsmeyer-Peppas model. The contact time study in the impregnation at 30 MPa, 35 ºC and 0.1 MPa/min revealed a slight increase in antioxidant capacity after six hours. Furthermore, samples with a more homogeneous colour distribution were obtained. |
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