Effects of gum karaya addition on the characteristics of loquat seed starch films containing oregano essential oil

Biodegradable films were developed from a novel source of starch, extracted from loquat seed, which is usually discarded. Oregano essential oil (OE) was incorporated into the loquat seed starch (LSS) film to confer bioactivity. The LSS films incorporated with 1.2% OE exhibited good antimicrobial activities as well as desirable mechanical properties. To enhance the homogeneity of OE in the film matrix, gum karaya (GK; 10%, 15%, and 20% of OE, w/w) was added as a stabilizing agent. The effects of GK concentration on the characteristics of the LSS films containing 1.2% OE were determined and compared with that of Tween 80. Results indicated that the addition of GK increased tensile strength and hydrophobicity of the film surface, whereas Tween 80 at high concentrations (15% and 20%) increased water solubility and roughness of the film. The presence of GK or Tween 80 increased opacity and water vapor permeability of the films, whereas the moisture content of the films decreased. Addition of GK or Tween 80 improved the distribution of OE in the films, and did not affect bioactivities, such as antimicrobial and antioxidant activities, of the films. These results suggest that GK may be used as a stabilizer in starch films containing essential oils as an alternative to Tween 80.