Food-grade porous materials, aerogels and so-called cryogels, were prepared from cellulose hydrogels obtained from solutions at increasing cellulose concentration (3, 4, 5%, w/w) by supercritical-CO2-drying (SCD) and freeze-drying (FD), respectively. The structure depended on the applied drying technique, with aerogels showing a denser network with pores <200 nm in diameter, a specific surface area of 370–380 m2g-1, and a porosity of 92–94%. Cryogels presented larger pores (2–5 μm diameter), much lower specific surface area (around 30 m2g-1), and higher porosity (95–96%). Water vapor adsorption by aerogels and cryogels was higher than that of neat microcrystalline cellulose. The absorption of water and oil was investigated as a function of time and at equilibrium. While water was almost immediately absorbed by both aerogels and cryogels, a much longer time was needed to reach oil absorption equilibrium. Moreover, aerogels required a longer absorption time than cryogels. Material morphology governed the kinetics of absorption; the absorption at equilibrium was directly dependent on material pore volume rather than on its morphology or material-fluid affinity. As a result, due to their lower pore volume, aerogels absorbed a lower amount of water or oil (4–8 gfluid/gdry matter) than cryogels (8–12 gfluid/gdry matter). All samples showed high fluid holding capacity (>96%). Water absorption caused a firmness decrease, but the firmness of oil-filled materials was the same as that of the unloaded ones. This study demonstrates that food-grade cellulose aerogels and cryogels can be structurally designed by varying cellulose concentration and drying techniques to obtain controlled food fluid loading.

Interactions of cellulose cryogels and aerogels with water and oil: Structure-function relationships

Ciuffarin F.;Plazzotta S.;Libralato M.;Calligaris S.;Manzocco L.
2023-01-01

Abstract

Food-grade porous materials, aerogels and so-called cryogels, were prepared from cellulose hydrogels obtained from solutions at increasing cellulose concentration (3, 4, 5%, w/w) by supercritical-CO2-drying (SCD) and freeze-drying (FD), respectively. The structure depended on the applied drying technique, with aerogels showing a denser network with pores <200 nm in diameter, a specific surface area of 370–380 m2g-1, and a porosity of 92–94%. Cryogels presented larger pores (2–5 μm diameter), much lower specific surface area (around 30 m2g-1), and higher porosity (95–96%). Water vapor adsorption by aerogels and cryogels was higher than that of neat microcrystalline cellulose. The absorption of water and oil was investigated as a function of time and at equilibrium. While water was almost immediately absorbed by both aerogels and cryogels, a much longer time was needed to reach oil absorption equilibrium. Moreover, aerogels required a longer absorption time than cryogels. Material morphology governed the kinetics of absorption; the absorption at equilibrium was directly dependent on material pore volume rather than on its morphology or material-fluid affinity. As a result, due to their lower pore volume, aerogels absorbed a lower amount of water or oil (4–8 gfluid/gdry matter) than cryogels (8–12 gfluid/gdry matter). All samples showed high fluid holding capacity (>96%). Water absorption caused a firmness decrease, but the firmness of oil-filled materials was the same as that of the unloaded ones. This study demonstrates that food-grade cellulose aerogels and cryogels can be structurally designed by varying cellulose concentration and drying techniques to obtain controlled food fluid loading.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11390/1245324
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