New acacia gums fractions: how their features affect the foamability of sparkling base wines?

Abstract

When sparkling wine is served, the first attribute perceived is foam1. Bentonite is usually added to wine in order to cause particle flocculation, but this procedure also leads to a drastic loss of foamability2. Acacia gums improve the foamability of some sparkling base wines treated with bentonite3. Acacia gums are already authorized as additives in wine production4. We studied how the addition of new fractions from Acacia gums affected the wines foamability. Our work deepens the relationship between wine foamability and gums fractions properties. Eight sparkling base wines were elaborated by the traditional white winemaking method. Three of them were elaborated in three different regions from Spain: Malaga using Moscatel grapes as well as Saragossa and Tarragona (TA), both using Macabeo grapes. The other five base wines were elaborated in the French region of Champagne using Chardonnay (4) and Pinot noir (1) grapes. They were treated with bentonite, stirred and filtered. Acacia senegal (Asen) and Acacia seyal (Asey) gums were fractionated by Ion Exchange Chromatography giving two high (F1sen and F1sey) and two low (F2sen and F2sey) molar mass fractions. Fractions and sparkling base wines were deeply characterized. Four Acacia gums fractions were separately added to wines (300 mg·L-1), resulting in “supplemented CO-wines”. Based on shaking test, wine was vigorously hand-shaken in closed tubes. The foam height at 5 and every 10 seconds during 90 seconds was measured (all in triplicate). The maximum foam height was improved in 11 out of the 16 supplementations (69%) with F1 fractions, which were the fractions with high protein amount and high molar mass. F1sey and mainly F1sen showed a positive effect improving the foamability in Spanish wines. F1 fractions also increased foamability of French wines, but in a more inefficient and irregular pattern. Moreover, the differentials of foam height (ΔFH) between “supplemented CO-wines” and CO-wines enhanced significantly in all the studied wines at several moments after supplementations with F1 fractions. F2 fractions gave enhancing effect only sporadically. Adding F1sen and F1sey, the foam height showed positive Pearson correlations with, respectively, (i) polysaccharides rich in arabinose and galactose percentage and (ii) the number average molar mass of polysaccharides. But after F1 supplementations, the mannoproteins percentage in base wines affected negatively their foamability. The Proteins %, the hydrophobic score, the volumetric properties, the molar masses, the high molar mass ranges and the content of several amino acids of gums fractions affected positively the foamability in different wines, whereas it was negatively affected by the sugars %.Concluding, sparkling base wine foamabilities strongly depend on the wine and the gum fraction addition, but also on their relationship.