Tannic acid adsorption properties of cellulose nanocrystalline/fish swim bladder gelatin composite sponge

Foods and beverages with excessive tannins acid (TA) content taste astringent and bitter. The overconsumption of TA could result in nutritional and digestive problems. In this study, the cellulose nanocrystals (CNC)/fish swim bladder gelatin (FG) composite sponge was prepared with glutaraldehyde as a crosslinking agent. The TA adsorption performance of the sponge was discussed. The freeze-dried CNC/FG composite sponge had a porous network structure. CNC was combined into the FG matrix as a reinforcing phase. The mechanical strength, thermal stability, and swelling properties of the composite sponge were improved with the addition of an appropriate amount of CNC. Although CNC decreased the porosity of composite sponge, the increase in active adsorption sites resulted in an overall positive effect on its TA adsorption properties. Under the optimal adsorption conditions, the TA removal rate of 1.0 % CNC composites reached 80.4 %. Furthermore, the sponge retained a TA removal rate of 54 % after five cycles of adsorption and desorption using 50 % ethanol. The results demonstrated that CNC/FG composite sponge has application potential in the field of adsorption materials for TA.