Protein Adsorption by Bentonite in a White Wine Model Solution: Effect of Protein Molecular Weight and Ethanol Concentration

Bentonite adsorption isotherms were evaluated with three standard proteins (bovine serum albumin, ovalbumin, and lysozyme). The effect of the ethanol concentration and protein molecular weight on the capacity of bentonite to adsorb protein was also studied in a model solution. Bovine serum albumin and ovalbumin adsorption isotherms were well fitted by the simple Langmuir model, but the lysozyme adsorption isotherm could not be fitted by any common model. However, the protein adsorption followed the same mechanism in the maximum adsorption area and there was no bentonite affinity for the proteins tested. The adsorption process depended on the physical volume of the protein. On a molecular level there was no adsorption selectivity. The adsorption capacity of bentonite tended to increase in ethanol for bovine serum albumin and lysozyme. There was no effect in ovalbumin.