Starch-based edible coating formulation: Optimization and its application to improve the postharvest quality of "Cripps pink" apple under different temperature regimes

This study demonstrated Response Surface Methodology (RSM) optimisation of starch edible coating formulation and its application on apple fruit quality and storage life at two different temperatures (20 degrees C and 5 + 1 day at 20 degrees C). Films were optimised for physical, mechanical and permeability properties and the optimal formulation was sprayed over the fruit surface. Fruit weight loss, respiration rate, total soluble solids (TSS), titratable acidity (TA), firmness, greasiness and change in the fruit skin colour were measured. The effect of the coating treatment on changes to the bioactive profile (phenolics and free radical scavenging activity) of the fruit was also analysed. The results obtained from this study showed that the optimised formulation (rice starch 2.5% 1-car 1.5% sucrose fatty acid ester 2% glycerol 1.5%) in combination with low temperature was effective in reducing weight loss and maintained tissue firmness without affecting TSS, TA and the bioactive profile of the apple fruit during postharvest storage. A delay in skin colour change and a significant reduction in fruit greasiness was observed in coated fruit (p < 0.05). These results show the potential of starch-based coating formulation in the formulation in improving the visual appearance, without affecting the fruit internal quality and nutritional properties of apple fruit during storage.