Effect of high-pressure homogenization on microstructure and properties of pomelo peel flour film-forming dispersions and their resultant films

Abstract

The pomelo peel flour (PPF) film-forming dispersions were physically modified by high-pressure homogenization (HPH) process at various pressures (0–80 MPa) to prepare biopolymer films. The effects of different HPH pressures on microstructure and properties of PPF dispersions and their resultant films were investigated. The results showed that as the homogenization pressure increased, the mean particle sizes of PPF dispersions decreased significantly from 78.76 μm to 19.87 μm, highlighting the disrupting effect of HPH. Meanwhile, the PPF dispersions after HPH exhibited a shear-thinning behavior with higher apparent viscosities and better colloidal stability, indicating the improved uniformity and consistency. Consequently, the resultant PPF films had not only more compact microstructure and transparent appearance, but also better water vapor barrier and mechanical properties. In particular, the PPF film from HPH treated dispersion at 60 MPa had relatively best performance among them, the tensile strength and elongation at break of which respectively increased from 9.88 to 23.55 MPa and 6.09% to 17.68%, while the water vapor permeability decreased from 4.10 × 10−10 to 2.08 × 10−10 g/m·s·Pa, compared to the untreated film. However, a slight deterioration in these above mentioned properties was observed for 80 MPa HPH treated films, which might be attributed to the undesirable degradations of biopolymers (such as pectin and dietary fiber) occurred at excessively high homogenization pressure. These findings reveal that HPH process has a potential application in developing novel biopolymer films from pomelo peel with enhanced properties.