## 1 Introduction  
An increase in consumer requirements for safe food has led to the development of new improved packaging systems, including active, intelligent and edible materials. The use of edible biopolymers in food-packaging applications has become an alternative due to their film-forming properties and environmentally friendly behavior [1]. Edible coatings and films are different: edible films are used as wrapping packaging materials, while edible coatings can be directly applied on the surface of food products [2]. Edible coatings are natural, safe and ecologically friendly substitutes, suitable to be applied to reduce water transfer, gaseous exchange and oxidation of fresh products [3]. The edible coatings should preserve the quality, nutritional value and texture of food products by reducing moisture loss and oxygen effects, while maintaining adherence, without altering the original taste and odor [4]. Furthermore, the combination of natural food grade substances in the coating should improve the physical properties of the formed films [5]. In fact, the rheological properties of the film-forming solution, such as thickness, spreadability and uniformity of the liquid coating layer, and the film performance, can be significantly affected by the type and composition of the coating constituents, such as polysaccharides, protein, hydrocolloid or composite materials. In general, a reduction in the solution's viscosity provides a processing advantage during high-shear processing operations, whereas high apparent viscosity at low-shear rates provides a better application by dipping [4]. Chitosan is a cationic biopolymer that can be mainly obtained from the deacetylation process of chitin, a renewable natural resource [2] which is widely used in the coating of fresh products. Biological properties have been attributed to chitosan, such as antibacterial and antifungal properties [6]. Then, the application of this substance has been applied in several areas such as agriculture, cosmetic, pharmacy and also food industry [7]. Chitosan has been studied and used for coating fish, meat, fruits and vegetables, to improve the quality and extend the food shelf life [8]. In addition, chitosan can be combined with other functional compounds with antioxidant, antimicrobial or other activities, to enhance the quality and efficacy of the coating [9]. Antioxidants, antimicrobial agents, coloring agents, flavors, nutrients, prebiotics and probiotics are examples of functional compounds that can be incorporated into edible chitosan-based coatings [10]. Particularly, for the case of strawberry (_Fragaria \(\times\) ananassa_), some works studied the application of chitosan-based coatings [11; 12] but a relatively high moisture permeability was reported [2]. Then, the incorporation of natural bioactive compounds such as nisin, natamycin, pomeranate, grape seed extracts [13], aloe vera gel [14], _Thymus capitatus_[15] and _Mentha spicata_ essential oils [16] and green tea extract [17], were studied, with the aim of enhancing the performance of the edible coating and the preservation of strawberry. This fruit has been intensively studied, because it is highly consumed [18] and is a relevant source of bioactive compounds such as vitamin C, vitamin E, \(\beta\)-carotene and anthocyanins [19]. Nevertheless, several factors can reduce the fruit quality and limit its commercialization, such as intrinsic physiology, physiological and mechanical lesion, fungal infections and postharvest decay [20; 21; 22]. On the other hand, licorice is a traditional therapeutic herb, which grows in various parts of the world, and is well recognized due to its bioactive properties, including antioxidant, anti-fungal, anti-ulcer, anti-inflammatory, as well as anticancer and antiviral. Licorice was commonly used in traditional medicine recipes for the treatment of respiratory complaints, inflammatory disorder and liver problems [23; 24]. Accordingly, licorice extracts, particular those obtained from the root, were studied as natural food preservatives.