Chitosan and Carnauba Wax Coatings Are Not Recommended for Yellow Carrots

Abstract

The objective of this study was to evaluate the use of different concentrations of carnauba wax and chitosan edible coatings for commercial quality preservation of ‘Yellow Stone’ carrots. Seven treatments were tested: Chitosan at concentrations of 1%, 3%, and 5%; carnauba wax at concentrations of 0.5%, 1%, and 12%, and a control treatment, without coating application. Carrots were stored at 2 °C, 95–100% RH, for 30 days, and were evaluated on the day of application (day 0) and at 7, 15, and 30 days. Indices of brown stains, coloring, and light microscopy analysis were developed. The use of edible coatings for yellow carrots was not viable, regardless of the treatment used, and carnauba waxes caused more severe brown stains. Higher concentrations of carnauba wax caused damage of the carrot periderm, generating, in addition to the stains, deep depressions and superficial viscosity. Only the control treatment showed no degradation in appearance. Treatments with the highest index scores presented lower luminosity, lower b color values, and higher a color values, which showed that the brown stains impacted carrot appearance and, therefore, their visual quality. The results showed that coatings based on chitosan and carnauba wax are not recommended for yellow carrots, since they negatively affected appearance of the product, leaving them unmarketable.