Supercritical impregnation of antioxidant mango polyphenols into a multilayer PET/PP food-grade film

Methyl gallate (MG) was used as a model substance to determine the influence of operating conditions on the supercritical impregnation of mango polyphenols into a multilayer polyethylene terephthalate (PET)/polypropylene ( PP) food-grade film. The effects of pressure (10-20 MPa), temperature (35-55 degrees C), impregnation time (3-22 h) and stirring were analysed. The most favourable conditions were obtained under 10 MPa at 45 degrees C during 22 h in stirring mode. These operating conditions were implemented in the impregnation of a mango leaf extract (MLE). The results show that the MLE-loaded PET/PP films presented a high phenolics load, predominantly in MG (similar to 30 mg MG/100 g film), antioxidant capacity, demonstrated by DPPH assay, and potential application in the preservation of perishable foods such as fruit and vegetables.