## 3 Results and Discussion
### Effect of Chitosan-Licorice Edible Coatings on Strawberries' Quality
#### 3.4.1 Physicochemical Effects  
In order to determine the effect of licorice extracts on the coated fruits, photographs were picked up during storage, which are shown in Figure 5. Pictures corresponding to 14 days of storage were also included in the figure, because the effect of coatings became very obvious. The coated strawberries presented a brilliant appearance, which was better than the uncoated sample. The coated forming on berries depends on the rheological parameters of the coating solutions, which present different shear stress and viscoelastic properties. The amount of coating solution adhered to strawberry during application strongly depends on the viscosity and the surface tension of the coating solutions. The roughness on the surface of strawberries require formulations with ingredients that can reduce the coating solution surface tension, in order to ensure coating uniformity and absence of void holes [4]. The total sugars present in fruit can act as a plasticizer, interacting with the polymer chains and generating \"free\" volumes within the chains, weakening the intermolecular forces and, consequently, reducing the resistance of the films [68]. Some authors determined that solutions with high viscosity and low surface tension promote a better film-forming surface [69]. In this study, the chitosan coating solution presented a viscosity of 170 mPa-s, while lower values were observed in the case of chitosan-licorice solutions (4.40 and 2.10 mPa-s for Ch + LE-1 and Ch + LE-5, respectively). Nevertheless, despite the observed viscosity reduction, the addition of LE improved the viscoelastic properties and allowed a better surface extensibility on berries, forming thinning coatings with higher uniformity and adherence, which can be related with the better physical appearance observed (Figure 5). The application of coatings did not affect the color of berries, maintaining good visual quality and no water migration on the surface was observed. The presence of mold was visually observed in the control sample on day 10 (Figure 6), while no mold was observed in the coated berries. Ch + LE-5 coating exhibits the best preservation of strawberry appearance. The fungal decay of samples is depicted in Figure 6. The percentage of fungal decay was higher in control samples, followed by chitosan samples, while chitosan-licorice coatings did not present fungal decay during 10 days of storage. The licorice extract increased the antimicrobial \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Table 1**} & \(\mathbf{J_{o}}\) & \(\mathbf{J_{1}}\) & \multirow{2}{*}{\(A_{ref}\) (s)} & \(\mathbf{\mu_{o}}\) & \multirow{2}{*}{\(\mathbf{R^{2}}\)} & **Recovery** \\  & **(mPa\({}^{-1}\))** & **(mPa\({}^{-1}\))** & & **(Pa-s)** & & **(\%)** \\ \hline Ch & 3.793 & 1.408 & 4864.0 & 1.282\(\times\) 10\({}^{6}\) & 0.998 & 35.82 \\ Ch + LE-1 & 0.482 & 0.481 & 906.3 & 1.878\(\times\) 10\({}^{6}\) & 0.999 & 83.78 \\ Ch + LE-5 & 0.801 & 0.6258 & 340.8 & 4.252\(\times\) 10\({}^{5}\) & 0.997 & 51.09 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Burger model parameters obtained for the films. Ch = Chitosan; Ch + LE-1 = Chitosan + 1% of licorice extract; Ch + LE-5 = Chitosan + 5% of licorice extract. properties of chitosan, according to the antibacterial activity assessed in this study and in other studies available in the literature [32]. Figure 7 shows the weight loss of uncoated and coated samples with the different films throughout the cold storage time. Postharvest mass loss of fruits and vegetables is mostly due to moisture loss through transpiration, and is recognized to accelerate the susceptibility of fruit and vegetables to physiological disorders [70; 71]. After only three days of storing, the uncoated sample presented less weight loss than the samples treated with any of the coatings. Nevertheless, on day 10, the barrier  
Figure 5: Visual appearance of uncoated, chitosan- and chitosan-licorice-coated strawberries corresponding to 1, 3, 10 and 14 days of storage at 4 °C.