A comprehensive study on the effect of bentonite fining on wine charged model molecules

Abstract

In bottled wines, haze and turbidity are phenomena to be avoided. Since bentonite fining is a common process to clarify wines removing heat unstable proteins, a theoretical study on the adsorption of three Charged Model Molecules (CMMs, egg albumin, polyphenols and riboflavin) was carried out to deep comprehend this chemical phenomenon. Four bentonites were adopted and finely characterized together with the potential release of Na⁺ and Ca²⁺ cations, revealing suitable for RT albumin removal within 120 min. Better results in terms of adsorbed quantity were achieved by adopting 12%v/v EtOH/H₂O solvent and by swelling bentonites for 24 h before use. With the most performing sample (Na/Ca_0.27), a comprehensive study on simultaneous adsorption of the three CMMs was performed, resulting in polyphenols adsorption increase due to their interactions with albumin. Notwithstanding the majority of albumin and riboflavin was successfully removed, ca. 40-50% of tested polyphenols was preserved.

Keywords: Adsorption; Bentonites; Kinetics; Wine charged model molecules; Wine fining.