**1. Introduction**

Postharvest losses of horticultural products restrict the availability of food in the world. With carrots, losses happen due to physical or esthetic flaws as a result of mechanical injuries, pathogen attack, shape defects, and withering [1,2]. Other studies led by our research group indicated that yellow carrots lose about 15% of fresh weight in only seven days when stored under ambient conditions (25 ◦C and 70% RH) (data not published).

Yellow carrots were recently embraced by Brazilian growers, appealing as a distinctive gourme<sup>t</sup> product, but one that does not have constant availability in the market. Better quality roots are obtained during a winter harvest and must be stored to maintain their availability for the longest time possible. However, this standard will only be achieved by adopting good postharvest practices, associated with the use of technologies that help to minimize losses and maintain the quality of the products for a longer period.

Edible coatings are considered the packaging of the future and may help reduce losses caused by withering (i.e., water loss. These coatings are thin layers of edible biopolymers made of proteins, polysaccharides, or lipids, which are applied directly onto a product surface, adhering to it as part of the final product. These materials create a barrier against physical injuries, microbiological contamination, loss or gain of moisture, and nutrient oxidation. Therefore, they help prevent product deterioration, extending storage life, sensorial quality, and safety. The difference between these coatings and plastic

packaging is the fact that the former is edible and biodegradable, and may substitute partially or totally for the latter [3,4].

Chitosan is the basis of edible coatings from non-starch polysaccharides. It is made by alkaline deacetylation of chitin, which is a polysaccharide present in the exoskeleton of crustaceans. Besides the usual properties of coatings, the film generated by chitosan provides a good barrier to oxygen, although it is not an efficient barrier against carbon dioxide. It also contributes to the control of enzymatic browning and microbial activity, as well as the capacity of absorbing ions of heavy metals. These properties play a role in minimizing the oxidation process catalyzed by free metals and delay changes in the content of anthocyanins, flavonoids, and total phenolics [3,5,6].

Among lipid coatings, natural waxes, such as carnauba wax, stand out. They are chemically classified as esters of long chain aliphatic acids. As a non-polar compound, they are an efficient barrier to the exchange of water vapor. Carnauba wax has better emulsifying, lubricity, plasticising, and adhering properties than other waxes, besides a greater permeability to O2. It also improves food appearance by providing gloss and improving superficial texture [7].

There are few studies that show the effects of edible coatings on carrot quality. Thus, our objective was to evaluate the use of different concentrations of two types of edible coatings, one of carnauba wax and the other of chitosan, on the conservation of the commercial quality of yellow carrots.

#### **2. Materials and Methods**

#### *2.1. Raw Material and Treatments*

'Yellow Stone' carrots were obtained from a commercial farmer (Araçoiaba da Serra, SP, Brazil, latitude, 23◦3019" S, and longitude, 47◦3651" O). Carrots were divided among seven treatments: (1) Control treatment (without coating application); (2) chitosan at a concentration of 1%; (3) chitosan at 3%; (4) chitosan at 5%; (5) carnauba wax at 0.5%; (6) carnauba wax at 1%; and (7) carnauba wax at 12%.

Chitosan (Nutrifarm do Brazil, São Paulo, Brazil, low molecular weight) was dissolved in a solution of 8% acetic acid and 1% glycerol. For applying coating, carrots were immersed in the solutions for 5 min and then kept on absorbent paper until the coating was fully dried. The carnauba wax with colophony (Aruá Comércio e Serviço LTDA., São Paulo, Brazil, BR12) was obtained at a concentration of 12% and diluted in distilled water for lower concentrations. Colophony is a wood rosin that acts as an emulsifier in carnauba wax. The wax application was made by using a cotton wool soaked in the solution. Then, carrots were laid on absorbent paper until the coating was fully dried. Finally, carrots were transferred to plastic containers (20 kg capacity) and stored at 2 ◦C, 95–100% RH for 30 days.

Analyses were performed on the day of coating applications (day 0) and after 7, 15, and 30 days. The study used a randomized experimental design with a factorial structure of 7 × 4 (treatments × days of analysis), with five repetitions of seven carrots (approximately 500 g) each.
