Exploring the role of pullulan in the process of potato starch film formation

It is well known that mixing pullulan (PUL) with starch can overcome the poor physical properties of pure starch based film. However, the mechanism of improvement of physical properties of starch film with PUL is yet to be clearly understood. The objective of this study is to investigate the effect of PUL in potato starch (PS) condensed matter solution and illustrate the mechanism improvement of physical properties of PS film by mixing with PUL. The moisture content of PS-PUL film decreased by 18.61 % because PS-PUL film chain-structure was denser than that of PS film. Based on the analysis of condensed matter solution, PUL could reduce the speed of PS chain movement and increase the flexibility of PS rigidity chains. Thus, tensile strength of PS-PUL film decreased by 20.34 % and elongation at break of PS-PUL film increased by 23.45 %. An increase in bending endurance by 49.51 % also illustrates that PUL improved the chain flexibility in the process of composite film formation. The present research provides a novel research route to understand the mechanism of hydrophilic colloids affecting the physical properties of starch film at molecular level. Also, the work provides a theoretical basis for the establishment of a correlation system between the microstructure and macroscopic properties.