Improving properties of curdlan/nanocellulose blended film via optimizing drying temperature

Curdlan (CD) and nanocellulose (NC) are both promising materials that can be applied for developing biodegradable and edible blended films. However, the extensive utilization in food active packaging is limited due to the relatively poor properties and long film-forming process. Regarding this, this work evaluated the impact of high drying temperatures (60 °C and 100 °C) on the functional properties of CD/NC blended films. First, the blended films were successfully prepared after optimizing the additional NC amount (5 wt%) and pH (4.5). The experimental results demonstrated that the mechanic properties and barrier properties of the blended films dried at 60 °C or 100 °C were comparable or improved to those of films dried at 25 °C in 24 h. Specifically, the tensile strength of the blended films dried at 100 °C in only 50 min was 29.63 MPa. Further, the results of low-field nuclear magnetic resonance (LF-NMR) indicated that water molecules worked as plasticizer. FTIR analysis revealed that the enhancement of the hydrophobic interaction between CD and NC were due to the increase of drying temperature and time. DSC and SEM results showed that at higher drying temperature (100 °C), the thermostability of the blended films could be enhanced because of the unique structure of CD and NC. Thus, the results of this work helped to understand the molecular mechanism of the CD/NC blended films during the drying process. This study might not only greatly promote the efficiency of film-forming, but also provide the potential commercial packaging for foods.