Effects of Palm Oil Nanoparticles in Diverse Physical States on the Properties of Starch Films

Most previous research focuses on single-state palm oil (PO) modification of starch films, while the interaction between different physical states PO and starch matrix has not been deeply discussed. This study aimed to investigate the effects of PO nanoparticles in three physical states (liquid, semi-solid, solid) on starch-based films, where the physical state of PO nanoparticles was regulated by manipulating the melting point of PO. PO nanoparticles with five different melting points (8, 24, 33, 42, and 53 °C) were prepared at 30 °C using emulsification with sodium caseinate as the emulsifier and were integrated within a starch matrix to fabricate films. The findings revealed that the starch film with 33 °C PO nanoparticles had the smoothest and most homogeneous surface, the best dispersion state of the oils, the optimal compatibility, and the highest film crystallinity. These films exhibited enhanced tensile strength (TS), stiffness, and barrier properties. Furthermore, starch films containing solid nanoparticles exhibited superior thermal stability. This study innovatively prepared nano-scale palm oil-starch composite films and revealed the pivotal role of the viscoelastic attributes of semi-solid PO nanoparticles in enhancing the qualities of starch-based films.