*4.4. Swelling studies*

Swelling studies were performed as described elsewhere [6]. Briefly, pectin aerogels and chitosan-coated pectin aerogels (without curcumin) were weighed and immersed in 100 mL of either SGF at pH = 1.2 or SIF at pH = 6.8, conditions mimicking the conditions of the gastrointestinal tract. Samples were collected after selected time intervals, blot-dried with tissue paper for removing excess solution and weighed. All experiments were performed in triplicate.

The swelling ratio was calculated using Equation (2):

$$S\_R = \frac{M\_S - M\_0}{M\_0} \tag{2}$$

where *MS* is the mass of the swollen aerogel after the selected period of time and *M*0 is the initial mass of the sample.

### *4.5. In-Vitro Dissolution Tests*

In-vitro dissolution tests for pectin aerogels and chitosan-coated pectin aerogels loaded with curcumin were performed using two dissolution media, SGF at pH = 1.2 and SIF at pH = 6.8, as described above. Aerogel samples were firstly placed in SGF for 2 h and immediately transferred to SIF for an additional 22 h.

In-vitro dissolution tests were performed following USP standards [23]. The experiments were carried out at 37 ± 0.5 ◦C on the Farmatester 3, USP II apparatus (Dema, Ilirska Bistrica, Slovenia). The volume of the dissolution medium was 900 mL, while the speed of rotation was set at 50 rpm. Aliquots of 2 mL for each sample were withdrawn at predetermined time periods and afterwards 2 mL of fresh dissolution medium was added to maintain a constant volume. Samples were subjected to a curcumin assay by a Cary 50 Probe UV spectrophotometer (Agilent Technologies, Santa Clara, CA, USA) at 429 nm. The concentration of curcumin was calculated using the calibration curves in SGF and SIF. All tests were performed in triplicate.
