Development of moisture-adsorbent cellulose aerogels with application in the packaging and preservation of fresh products

Abstract

Moisture condensation inside packages is one frequent problem when packaging fresh stuff such as vegetables. This process leads to microbial deterioration, loss of nutrients, increased enzymatic degradation, and shelf-life reduction. In this study, cellulose and carboxymethylcellulose (CMC) based aerogels were developed as an environmentally -friendly alternative to minimize condensation. Initially, aqueous dispersions between 1 and 5 % (w/w) were prepared for each material. CaCO₃ and CaCl₂ were evaluated as chemical cross-linkers (5 % w/w). Aerogels were obtained starting with high-speed dispersion (15500 rpm), followed by ultra-cooling (−45 °C for 24 h) and finally freeze-drying (−75 °C for 24 h). The aerogels were characterized by measuring different thermophysical properties. The aerogel with the highest moisture adsorption capacity (C_ads) obtained was that of cellulose + CaCl₂ (5 % each in aqueous dispersion) with an equilibrium water vapor adsorption (C_ads) of 0.58 g g⁻¹ at 20 °C and 60 % RH. The moisture adsorption on that aerogel was modeled by fitting a combined pseudo-first-order kinetics and an adsorption equilibrium equation (GAB) obtaining an adjusted R² of 0.864. The aerogel performance was experimentally evaluated by packaging freshly cut melon (95 g) together with 3–6 g of aerogel blocks in perforated polyethylene terephthalate (PET) trays at 8 °C and 80 % RH. A shelf life of 8 days was achieved for the cut fruits compared to 3 days for samples in open trays and 5 days for fruits in closed trays without aerogel. The cellulose-based aerogels can be a suitable and sustainable alternative for sustainably preserving fresh products in active packaging.