Evaluation and modeling of mass transfer properties of edible films produced from casein-lipid emulsions for fruit and vegetable coating applications

Edible films were cast from solutions of sodium or calcium caseinate and from emulsions of these proteins with beeswax, stearic acid, and acetylated monoglyceride. The water vapor permeabilities of the films were evaluated at 5{dollar}spcirc{dollar}C and 25{dollar}spcirc{dollar}C. Relative humidity at the film underside was calculated applying an analytical solution.; Adjustment to pH 4.6 (isoelectric point), calcium ion crosslinking and combined effects of calcium ascorbate buffer reduced water vapor permeability of sodium caseinate films. These effects were not seen in caseinate/acetylated monoglyceride emulsion films.; Incorporation of caseinates in edible films formulations resulted in swelling at high caseinate levels. Water vapor permeability increased as thickness of caseinate films increased. Changes in % relative humidity at the film underside at different film thickness appears to be one of the causes of the water vapor permeability anomaly in hydrophic films. Water vapor permeability of emulsion films varied by a factor of two depending on emulsion film orientation, as evidence of non-isotropic structure. Water vapor permeability increased at the low temperature condition for caseinate-based films. It is concluded that thickness, temperature and orientation effects are related to the hydrophilic nature of caseinate films. It is recommended to have permeability or permeance data of edible films corresponding to actual food application conditions, namely temperature, % relative humidity and thickness.; Considering the uncertainty of using mass transfer properties of stand-alone edible films in a mathematical model, an alternative approach to identify promising edible emulsion films for fruit and vegetables coatings was to test different coatings formulations directly on specific fruits and vegetables at given storage conditions and utilize a statistical model to predict increased water vapor resistance and shelf-life, based on optimization by respond surface methodology. Casein-based edible coatings were investigated for apples, zucchini fruits, and minimally processed celery sticks and peeled carrot sections. Casein-based edible coatings increased water vapor resistance and shelf-life without affecting respiration or ethylene production in those produces.