Superficial Charge Density of Fining Agents: Influence of pH, Dose, and Temperature

Abstract

The effects of pH, dose, and temperature on the superficial charge density of fining agents were determined in a model solution. This study included three gelatines and one egg's albumin, all of which are common fining agents, as well as three wheat glutens (one native and two hydrolyzed). Wheat glutens have been allowed to be used as fining agents only since 2005, and there are no preliminary studies examining them. The results of this study showed that the superficial charge density was mainly pH-dependent (p < 0.01), and that pH showed a greater effect at a higher degree of protein hydrolysis. For Gel 3, albumin and the wheat glutens, a larger protein concentration, decreased the superficial charge density. Gel 2, which was soluble in hot water, had the highest superficial charge density (>0.831 meq g⁻¹), which indicated that it would be more reactive than the other fining agents. Between pH 3.4 and 4.0, Gluten 1 and Gel 3 were more highly charged (superficial charge density >0.3 meq g⁻¹) than Gel 1 or the hydrolysed glutens. These data are useful for wine producers.

Keywords:

• Gelatine
• Albumin
• Wheat
• Electric properties
• Regression