Modified Cellulose-Based Edible Polymer Coating: An Investigation of Castor Oil Concentration for Application in Apple Preservation

The purpose of this study was to evaluate the effect of adding various concentrations of castor oil (2% and 4% v/v) on the properties of edible films based on carboxymethyl cellulose (CMC). Moisture content, water solubility, tensile strength, elongation at break, elastic modulus, water vapor permeability, optical and thermal properties and antioxidant activity of the films were examined. The results demonstrated that the presence of castor oil led to a decrease in moisture content, water solubility and mechanical strength of the films. The film containing 4% of oil showed the highest water vapor permeability. The optical properties measurement represented that all of the samples were transparent. By the addition of castor oil, the antioxidant activity of the films improved largely. Thermal properties of the samples had also been investigated and it was determined that the effect of castor oil on the melting point was negligible. Finally, the performance of the coatings for protecting fresh apples was studied with measuring the pH value of apples and performing some field test.