Dynamic behaviour of starch-based coatings on fruit surfaces

A method to characterising the surface water relations of coated fresh fruit has been developed. Based on a modification of the Fick's law of diffusion, application of this method allows for a quantitative assessment of the impact of produce type and of production method of coating, and environment on water losses both of the fruit body and the coating. Resistances in the water vapour pathway were analysed to determine the effects of coating on the surface water relations of plums. Experiments were conducted, evaluating the dynamic behaviour of two different starch-based coatings both at high and low potential water losses. Applying three layer-coatings, both starch and starch-whey protein coatings increased the total resistance in the water vapour pathway of individual plums by 60-75% at high transpiration potentials. Even at low transpiration potentials, an increase of 11-20% was observed. The starch coating tended to have a slightly lower effectiveness than the coating enriched with 20% whey protein.