Antimicrobial and physical properties of a chickpea protein isolate-based film containing essential oil of thyme using response surface methodology

The use of bio-polymers، especially proteins and herbal essences، has received attention for years in the production of edible films. The aim of this study was to prepare edible films based on isolated chickpea protein and determine the effects of concentrations of chickpea protein، glycerol and essence on antimicrobial properties، as well as water vapor permeability and solubility، of the edible film. Protein was extracted from Filip variety chickpea powder by the isoelecteric point sequestration method. Then، samples of edible films were prepared using protein (4-10g)، glycerol as a plasticizer (40-60%)، and thyme essence (0-1%). The antimicrobial effect of the film samples on Staphylococcus aureus and Escherichia coli، theirwater-vapor permeability and surface-solubility، by the response-surface method، were determined. Thyme essence brought about statistically significant reductions (P<0. 01) in the growth of the two microorganisms، as well as solubility and water vapor permeability of the films; the higher the protein concentration، the higher the permeability and the lower the solubility (P<0. 01) ‎. Also، higher glycerol concentrations led to increased permeability and solubility (P<0. 01). Based on the findings، it can be concluded that isolated protein of chickpea can form films. The optimum levels of isolated chickpea protein، glycerol and thyme essence for maximum anti-microbial effects، minimum water-vapor permeability and maximum solubility are4g، 44. 4% and 1%، respectively.