## 4 Conclusions  
In this study, the ultrasound-assisted extraction using solvents with different polarities and two temperatures (25 and 50 \({}^{\circ}\)C) was carried out, in order to obtain bioactive licorice extracts (LE) for the elaboration of edible coatings. The polarity of the solvent contributed to the extraction of specific compounds, and while temperature did not significantly affect the extraction yield, it influenced the TPC content of samples. A higher concentration of glabridin was obtained with ethanol solvent, showing a positive effect on the antioxidant activity of the extract. Nevertheless, ethanolic licorice root extracts did not present antimicrobial activity. On the other hand, the extraction with mixtures of ethanol or methanol with water (50:50 \(v\)/\(v\)) enhanced the extraction of polar biomolecules (such as glycyrrhizin), and the extracts presented good antimicrobial activity but less antioxidant capacity in comparison with the ethanolic extract. The edible coating solutions elaborated with pure chitosan and with chitosan and licorice ethanol:water extract, presented a non-Newtonian flow behavior. Solutions of pure chitosan presented shear thinning behavior, and the addition of LE decreased the shear stress value and presented a shear thickening behavior, probably due to particle hydro-clustering and an order-to-disorder transition. The viscoelastic properties of the coating solution show that the restructuring ability of Ch + LE physical gels improve the properties of film forming. Then, the addition of licorice phytochemical to chitosan increased the viscous properties of film, displayed a variation in the dissipation energy (G\({}^{\prime\prime}\)) and films became more flexible with the addition of LE. Furthermore, the addition of LE to chitosan decreased the shear stress values of samples, allowing better physical properties of the films applied on strawberries. Concerning the preservation capacity, the addition of LE increased the antimicrobial properties of chitosan, according to the antibacterial activities studied in vitro. The values of weight loss of these coatings were significantly lower than those corresponding to pure chitosan. Additionally, the chitosan + LE edible coatings better preserved the content of phenolic compounds in the berries. Then, the ultrasound-assisted extraction of bioactive compounds of licorice root using ethanol:water (50:50 \(v\)/\(v\)) is an alternative for producing bioactive licorice extracts with \begin{table}
\begin{tabular}{c c c} \hline \hline
**Bacteria and Yeasts** & **Treatment** & **Total Viable Count (Log CFU/g) on Day 6 of Cold Storage** \\ \hline \multirow{3}{*}{Mesophilic} & Uncated & 7.0 \(\pm\) 2.0 \\  & Ch & 4.5 \(\pm\) 0.7 \\  & Ch + LE-1 & n.g. \\  & Ch + LE-5 & n.g. \\ \hline \multirow{3}{*}{Psychrophilic} & Uncated & 4.0 \(\pm\) 0.01 \\  & Ch & 4.0 \(\pm\) 0.01 \\  & Ch + LE-1 & n.g. \\  & Ch + LE-5 & n.g. \\ \hline \multirow{3}{*}{Yeasts} & Uncated & 4.0 \(\pm\) 0.01 \\  & Ch & 4.0 \(\pm\) 0.01 \\ \cline{1-1}  & Ch + LE-1 & n.g. \\ \cline{1-1}  & Ch + LE-5 & n.g. \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Effects of edible coatings prepared with chitosan and chitosan + licorice extract on the growth of mesophilic and psychrophilic bacteria (total aerobic psychrophilic bacteria) and yeasts during storage at 4 \({}^{\circ}\)C. Ch = Chitosan; Ch + LE-1 = Chitosan + 1% of licorice extract; Ch + LE-5 = Chitosan + 5% of licorice extract. potential application in the elaboration of edible coatings with good rheological properties and preservative capacity. Conceptualization, M.R.G.-R.; L.A.G.-Z., and T.F. ; methodology, S.E.Q. ; M.R.G.-R.; L.A.G.-Z., and T.F. ; software, O.L. and S.E.Q. ; validation, T.F., formal analysis, S.E.Q., M.R.G.-R., L.A.G.-Z., and T.F. ; investigation, S.E.Q., O.L., resources, S.E.Q., O.L., M.R.G.-R.; L.A.G.-Z. and T.F., writing--original draft preparation, S.E.Q. and T.F. ; writing--review and editing, S.E.Q., O.L., L.A.G.-Z., M.R.G.-R. and T.F., supervision, T.F., M.R.G.-R. and L.A.G.-Z.