*Article* **Preparation and Characterization of Chitosan-Coated Pectin Aerogels:** *Curcumin* **Case Study**

### **Milica Panti´c, Gabrijela Horvat, Željko Knez and Zoran Novak \***

Faculty of Chemistry and Chemical Engineering, University of Maribor, Smetanova 17, 2000 Maribor, Slovenia; milica.pantic1@um.si (M.P.); gabrijela.horvat@um.si (G.H.); zeljko.knez@um.si (Ž.K.) **\***

 Correspondence: zoran.novak@um.si; Tel.: +386-2-2294-405; Fax: +386-2-2527-774

Academic Editors: Carlos A. García-González, Pasquale Del Gaudio and Ricardo Starbird Received: 20 December 2019; Accepted: 5 March 2020; Published: 6 March 2020

**Abstract:** The following study describes the preparation of pectin aerogels and pectin aerogels coated with an external layer of chitosan. For the preparation of chitosan-coated pectin aerogels, a modified coating procedure was employed. Since pectin as well as pectin aerogels are highly water soluble, a function of chitosan coating is to slow down the dissolution of pectin and consequently the release of the active substances. Textural properties, surface morphologies, thermal properties, and functional groups of prepared aerogels were determined. Results indicated that the coating procedure affected the textural properties of pectin aerogels, resulting in smaller specific surface areas of 276 m<sup>2</sup>/g, compared to 441 m<sup>2</sup>/g. However, chitosan-coated pectin aerogels still retained favorable properties for carriers of active substances. The case study for prepared aerogels was conducted with curcumin. Prior to in-vitro release studies, swelling studies were performed. Curcumin's dissolution from both aerogels showed to be successful. Pectin aerogels released curcumin in 3 h showing a burst release profile. Chitosan-coated pectin aerogels prolonged curcumin release up to 24 h, thus showing a controlled release profile.

**Keywords:** curcumin; pectin aerogels; chitosan coating; burst release; controlled release
