Improving properties of thermoplastic starch films by incorporating active extracts and cellulose fibres isolated from rice or coffee husk

Hydrothermal (60 min, 180 degrees C) extracts and cellulose fibres from coffee and rice husks were obtained to be incorporated into corn starch films, in order to improve the film functional properties as food packaging material and confer them active properties. Extracts exhibited antioxidant properties (EC50: 5.37-5.29 mg extract solids/ mg DPPH) and antibacterial activity against Listeria innocua and Escheriquia coil (MIC values: 35-45 and 34-35 mg extract solids/mL, respectively). The active extracts improved tensile properties of the starch films; elastic modulus increased by about 350% and films become less stretchable. The cellulosic fibres from both residues were more effective as reinforcing agents in films containing extract solids than in net starch films. Extracts also provoked 30% reduction in the WVP of starch films and 50-85 % reduction in the oxygen permeability, depending on their amount in the films, but no effect of cellulose fibres was observed on barrier properties.