4.3.3. Textural Properties

Specific surface areas (m<sup>2</sup>/g) of synthetized aerogels were determined by gas N2 adsorption-desorption analysis. The experiments were carried out at −196 ◦C using ASAP 2020MP (Micromeritics Instrument, Norcross, GA, USA). Prior to analysis, the samples were degassed under vacuum at 70 ◦C for 660 min until obtaining a stable 10 μm Hg pressure. BET (Brunauer–Emmett–Teller) method was employed for determining the specific surface area. Skeletal densities of aerogels were measured by gas pycnometer using AccuPyc II 1340 (Micromeritics Instrument, Norcross, GA, USA), while bulk densities were determined by simply measuring sample mass (weighting) and volume (dimensions). Finally, porosity was determined using Equation (1):

$$Porosity\left(\%\right) = 1 - \frac{\rho\_{skcletal}}{\rho\_{bulk}}\tag{1}$$

where ρ*skeletal* is skeletal density, while ρ*bulk* is bulk density of aerogels.

### 4.3.4. Fourier Transform Infrared Spectroscopy

Fourier transform infrared spectroscopy using IRAffinity-1s (Shimadzu, Kyoto, Japan) was employed for characterization of pectin aerogels, chitosan-coated pectin aerogels, and curcumin. The collection of the absorption bands was used to confirm the identity of polysaccharides and curcumin and also for detection of curcumin loaded into aerogels. Aerogels were characterized by ATR-IR method. The samples were cut into halves and placed on the ATR detector. On the other hand, curcumin was ground into a fine powder and dispersed into a matrix made of potassium bromide (KBr). This is the most common method for solids.
