Use of microbial levan in edible films based on cassava starch

The objectives of this work were to produce microbial levan using the microorganism Bacillus subtilis natto CCT 7712, and to apply this levan in edible films based on cassava starch to obtain new biopolymer blends with functional properties for use in food protection. The films were produced by solution casting, four formulations were produced with different starch: levan proportions (100: 0, 90: 10, 80: 20 and 70: 30), and glycerol was used as a plasticizer (20 g/100 g solids). All formulations resulted in films that had a good appearance, without bubbles or cracks. Atomic-force microscopy of the films showed a compact and homogeneous structure, indicative of good compatibility between the polymers. The addition of levan resulted in films with higher solubility, tensile strength and elongation and lower water vapor permeability. Microbial levan was shown to be an interesting functional ingredient for use in edible starch films, improving their barrier and mechanical properties. It can be a cost-effective alternative because it enables the use of levan in mixtures with a low-cost, high-availability material such as starch.