Composite bioaerogels fabricated from konjac glucomannan and gellan gum by supercritical carbon dioxide drying and impregnation thereof with β-carotene and phenolics of mango peel.

Bioaerogels were obtained by supercritical CO2 (scCO2) drying of a composite hydrogel fabricated from konjac glucomannan and gellan. The hydrogels became stiffer and more resilient as they transitioned to alcogels, prior to scCO2 drying. Drying was performed at two levels of pressure (100 and 150 bar) and temperature (55 and 65 °C). The maximum surface area (68.61 m2 g-1) and the lowest bulk density (0.032 g cm-3) of the bioaerogel were observed at 100 bar|55 °C, which resulted in high swelling and oil absorption. The freeze-dried counterpart (cryogel) on the other hand, exhibited low surface area (2.46 m2 g-1) and high amorphousness. The glass transition temperature (Tg) was significantly higher for more porous aerogels. The aerogels were impregnated with β-carotene and phenolics from mango peels, which is the first of its kind. Static scCO2 impregnation resulted in a greater loading of β-carotene and phenolics in the aerogels from the mango peels than semi-dynamic impregnation. However, wet impregnation was found to be more efficient than scCO2 impregnation, as it resulted in good retention of β-carotene and phenolics in the aerogel. The loading of β-carotene onto the aerogels prevented ultraviolet-induced degradation and facilitated a controlled in-vitro release in gastrointestinal fluids.