气凝胶
微晶纤维素
化学工程
吸水率
吸附
比表面积
多孔性
吸收(声学)
材料科学
纤维素
体积热力学
超临界流体
复合材料
化学
有机化学
催化作用
工程类
物理
量子力学
作者
Francesco Ciuffarin,Marion Négrier,Stella Plazzotta,Michele Libralato,Sonia Calligaris,Tatiana Budtova,Lara Manzocco
标识
DOI:10.1016/j.foodhyd.2023.108631
摘要
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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