Wettability of starch-gellan coatings on fruits, as affected by the incorporation of essential oil and/or surfactants

Abstract

[EN] Wettability of coating-forming systems (CFS) based on starch-gellan (80:20) blends, containing or not, emulsified/lecithin-encapsulated thyme essential oil (EO), was analysed in apple, tomato and persimmon fruit. Different concentrations (0-10(5) mg/L) of Tween 85 were incorporated into the CFS in order to know its potentially beneficial effect on the coating spreadability. These fruit skins exhibited high values of the surface tension dispersive component, while being low-energy surfaces (21-29 mN/m). Values of contact angle and surface tension of the starch-gellan solutions were positively affected by the addition of Tween 85 at 5.10(4) mg/L. However, it exerted a negative effect when the CFS contained emulsified or lecithin-encapsulated thyme essential oil. Likewise, wettability of starch-gellan coatings was notably improved with Tween 85 at 5.10(4) mg/L, whereas formulations containing emulsified or encapsulated EO did not require surfactant to improve their already good spreadability.