Exploring the effect of coagulation solvents on structure, functionalities, and sensory properties of cellulose aerogels intended for food application

Cellulose aerogels are mesoporous materials prepared through cellulose solubilization, gelation, coagulation, solvent-exchange, and supercritical-drying, showing high potential as advanced food ingredients. Although cellulose aerogels are well-known for their high porosity, low density, and high absorption capacity, limited information exists on how different coagulation media influence their structural integrity, ability to interact with food fluids and sensory attributes, critical parameters for their applicability in food formulations. This study aims to fill this knowledge gap and to identify coagulation conditions suitable for producing cellulose aerogels with optimal properties for food use. Cellulose coagulation was conducted using different food-grade antisolvents: ethanol, water, or acidic solutions of acetic (AcOH) or hydrochloric acid (HCl). Coagulation with ethanol, water, and 0.5 mol/L acid solutions minimally altered the shape of the samples, while higher acid concentrations resulted in irregular shapes and surface cracks. Ethanol- and water-coagulated aerogels showed, respectively, the lowest and highest volume contraction, firmness, and density, while AcOH- and HCl-coagulated aerogels presented intermediate values. All the aerogels showed similar fibrillated networks, accounting for comparable internal surface areas (>150 m2/g), and high water and oil absorption capacity (around 3 g fluid/g aerogel). Ethanol coagulation was shown to be the fastest and most resource-efficient in terms of solvent usage, followed by acid and water ones. However, cellulose coagulation with water and AcOH led to aerogels with lower sodium content and saltiness perception.