Testing the effectiveness of Cell-Wall material from grape pomace as fining agent for red wines

Abstract

Lately several works highlighted the capacity of grape cell-wall material (CWM) to interact with proanthocyanidins (PA), indicating its potential use as fining agent for red wines.1–4 However, those studies were performed by using purified PAs and very high doses of CWM (almost ten-fold higher than those used in wine industry for other commercial fining agents). The present study focuses on the applicability of CWM from Cabernet sauvignon pomace as fining agent for red wines under real winery conditions. Grapes of cultivar Cabernet sauvignon were harvested at three different maturity levels (unripe, mature, and overripe) and used for red winemaking. The pomace of such vinifications were used as source of CWM, and applied into red wines at two different concentrations: 0.2 g/L and 2.5 g/L. The effectiveness of the treatments with CWM was assessed by analyzing the color and phenolic composition of treated wines. Using the lowest dose (0.2 g/L) of CWM has little influence on the color and the phenolic composition of treated wines. However, the highest dose (2.5 g/L) of CWM statistically decreases the phenolic content of wines and modifies their chromatic features: decreasing color intensity (CI) and increasing tone (T). The effect of CWM treatment is greater for wines from unripe and overripe grapes than for wines from mature grapes. In contrast, the maturity level of grapes used for obtain CWM from grape pomace has a little effect on the effectiveness of fining treatment, since the three CWM used (from unripe, mature, and overripe grape pomace) show similar impact on wine color and phenolic composition. Given all this, it seems that the applicability of CWM as fining agent strongly depends on the initial phenolic composition of wines. Besides, high doses of CWM are required to achieve wine clarification. Thus, our results seem to disclose the limitations of using CWM as fining agent at industrial scale.

(1) Guerrero, R. F.; Smith, P.; Bindon, K. Application of Insoluble Fibers in the Fining of Wine Phenolics. J. Agric. Food Chem. 2013, 61 (18), 4424–4432. (2) Bindon, K.; Smith, P.; Kennedy, J. Interaction between grape-derived proanthocyanidins and cell wall material. 1. Effect on proanthocyanidin composition and molecular mass. J. Agric. Food Chem. 2010, 58 (4), 2520–2528. (3) Bindon, K.; Smith, P. Comparison of the affinity and selectivity of insoluble fibres and commercial proteins for wine proanthocyanidins. Food Chem. 2013, 136 (2), 917–928. (4) Bautista-Ortín, A. B.; Ruiz-García, Y.; Marín, F.; Molero, N.; Apolinar-Valiente, R.; Gómez-Plaza, E. Remarkable proanthocyanidin adsorption properties of monastrell pomace cell wall material highlight its potential use as an alternative fining agent in red wine production. J. Agric. Food Chem. 2015, 63 (2), 620–633.