Improving physical properties of sodium caseinate based coating with the optimal formulation: Effect on strawberries’ respiration and transpiration rates

The objective of the work was to improve the physical properties of caseinate (SC)-based coating by using a thickening agent, guar gum (GG), and a solid fat phase, beeswax (BW). To this aim, the effect of GG, BW, and surfactant concentration, varying the hydrophilic-lipophilic balance (HLB) values given by surfactant combination, on the physicochemical properties of the caseinate-based blends and film has been investigated. The best formulation has been applied to strawberries to quantify the impact of the coating on respiration and transpiration rates. The results showed that GG, BW, their interaction, and HLB affected the physical properties of the sodium caseinate-based coating. The formulations most physically stable and containing small and uniform solid BW particles were those with an HLB of 9.2. GG affected the viscosity of the blends, whereas the effect of beeswax concentration on viscosity was very low. A 50% of reduction of water vapor permeability was obtained by changing GG and BW concentration. The best formulation, containing 8% SC, 0.2% GG, 2% BW, and Tween 80 and Span 80 at HLB of 9.2, was able to reduce the respiration and transpiration rates of strawberries by 17% and 40%, respectively, at 4 °C and relative humidity higher than 86%.