Comparison of two procedures to measure foamability from sparkling base wines supplemented with acacia gums

Abstract

In sparkling wines, foam is a relevant aspect whose measurement method could affect the results. The shaking test (ST) is a simple method measuring foamability1,2. But, unlike the most used and classical sparging-gas method (the so-called Mosalux; MOS)3, the amount of gas introduced is not controlled. MOS is, however, longer and needs more complex equipment. Our work compares both methods trying to demonstrate that ST can be an alternative and reliable method easily used by winemakers and enological laboratories.Eight base wines were elaborated by the traditional method, treated with bentonite, stirred and filtered. The origins of three base wines were three different regions from Spain (using Moscatel and Macabeo grapes). The other five were elaborated in the French region of Champagne (using Chardonnay and Pinot noir grapes). Four Acacia gums fractions were separately added to two selected wines (one French wine and one Spanish wine). These two (six modalities: control, bentonite-treated and gums fractions-treated wines; n=12) and the other six wines (two modalities: control and bentonite-treated wines; n’=12) were analyzed by MOS and ST. In this way the differences of wines were not only caused by the origin and by the cultivar but also by varying oenological techniques, ensuring a great variability of samples. Using MOS, wine was in a glass cylinder with a frit at the bottom injecting CO2. The Maximum Foam Height (HM-MOS) and the Foam Stability Height (HS-MOS) were measured. In ST, wine in tubes was strongly hand-shaken. The foam height was measured at 5 sec. (ST5) and every 10 sec. (ST10, ST20…) during 90 seconds (all in triplicate).ST required six times less amount of wine and gum fractions than MOS. The Maximum Foam Height by ST (HM-ST) was always reached at ST5 (closely followed by ST10). The foam stability period (when foam height was not statistically different to the last measure) always started before or just at ST70. In all modalities of both selected wines, HM-MOS and HM-ST presented similar ANOVA-statistical relationships. However, HS-MOS and ST90 were statistically related only in one selected wine. Multiple regression analyses were performed trying to know if some correlation could be established between (i) the foam height values at T5 and T10 by ST and (ii) the HM-MOS of 24 varying wines, as well as between (I) the foam height values at T70 and T90 by ST and (II) the HS-MOS. T5 and T10 were selected as the two moments presenting the two higher foam height values. T70 and T90 were selected as the two moments when the foam stability period began and finished. Multiple Regressions showed that HM-MOS correlated with ST5-ST10, and HS-MOS with ST70-ST90 (R2>70%; p