Changes in the chromatic properties of red wines from Vitis vinifera L. cv. Merlot and Pinot Noir during the course of aging in bottle

Author: Alin Dobrei^*, Mariana-Atena Poiana, Florin Sala, Alina Ghita and Iosif Gergen

Received 11 January 2010, accepted 22 April 2010.

Abstract

Differences in color of red wines from Vitis vinifera L. cv. Merlot and Pinot Noir grapes (vintage 2005, winemaking center Recas) were examined during the course of aging in bottle for a period of two years.The parameters evaluated in our study included chromatic parameters (color intensity and tonality), color structure (color due to monomeric anthocyanins, polymeric pigments and copigmented anthocyanins), monomeric anthocyanins content, “chemical age” and ionization of anthocyanins for red wines as young and after 4, 10, 18 and 24 months of aging in bottle. During the aging, the color intensity decreased and the tonality increased. The highest value of color intensity was registered for the young red wine Merlot (8.708) and the lowest values for Pinot Noir aged for 24 months (6.611). For color tonality, the highest value was recorded for Merlot wine after ageing in bottles for 24 months (0.96) and the smallest for young red wine Merlot (0.64). During the course of aging in bottle, the monomeric anthocyanins content decreased from 179.44 to 122.29 mg L^-1 for Merlot wine and from 132.81 to 85.72 mg L^-1 for Pinot Noir. By ageing, the fraction of color due to polymeric pigment increased on the basis of decreasing of color percentage due to monomeric and copigmented anthocyanins. Percentage of color assigned of copigmented anthocyanins after ageing in bottles for 24 months decreased for both analyzed wines from 22.71% to 10.87% for Pinot Noir wine and from 35.49% to 19.19% in the case of Merlot wine. Pinot Noir aged in bottle for 24 months showed the greatest contribution of polymeric pigments (67.96%) to the wine color. The ”chemical age” of the wines, assessed on the basis of I₁ and I₂ indices, increased for both analyzed red wines but in different manner according to the color stabilization phenomenon. The values of these indices are very different in rapport with grapes variety and the aging time. The results are important in anticipation of the red wine color evolution during the course of aging. It outlines the idea that the red wine color can be influenced by the choosing of the aging time.

Key words: Red wine, Merlot, Pinot Noir, chromatic parameters, anthocyanins, aging process, ”chemical age”.