Hydroxycinnamic acids in grapes and wines made of Tannat, Marselan and Syrah from Uruguay

Abstract

Background: Hydroxycinnamic acids (HCA), present in pulp and skin of grapes, are relevant compounds in red winemaking. They catalyze oxidation reaction, but also participate in the formation of pyranoanthocyanins, thus contributing to the red-wine color stabilization. Aim: the current investigation aimed to study the HCA content and profile in Tannat, Marselan and Syrah Vitis vinifera grapes harvested at different maturation degrees and in the respective wines. A further aim was to study the evolution of these compounds in wine during bottle storage. Material and methods: two vintages were considered, 2015 and 2016. Two harvest dates around technological maturity were evaluated on each grape-cultivar. Winemaking (involving 70kg of grapes each) were made in duplicate by traditional maceration. Skin samples were taken before each vinification, freezed dried, and extracted with a mixture 50:48.5:1.5 of CH3OH/H2O/HCOOH. Hydroxycinnamic acids in skin and in the wines were isolated using SPE PCX cartridges, and injected into an HPLC-ESI-IonTrap-MS/MS system equipped with a C18 column. Wines were analyzed 3 months after winemaking, and during wine storage, up to 24 months after the first analytical determinations. trans-caftaric acid, cis and trans-coutaric acid, trans-fertaric acid, the correspondent free HCA and glucosides of these compounds were identified and quantified. Results: In the skin, caffeic acid-based HCA (Caff.) were the main HCA found (between 60% and 81%). The p-coumaric based HCA (p-coum.) represented the second most important cinnamic acids in 2015 (between 14%-37%) while proportion of Ferulic HCA based compounds (Fer.) represented between 2% and 5%. In 2016, Tannat and Syrah, had a much lower proportion of p-coum. (as low as 5% and 13% respectively), and a much higher proportion of Fer. (21% and 24% respectively), thus, the HCA skin profile could change among vintages. Skin HCA profile also changed among cultivars. Tannat had the highest proportion of Caff. which were much lower in Marselan and particularly in Syrah, and the lowest proportion in p-coum, which reached the highest values in Syrah. Grape ripeness did not modify the skin HCA profile in Syrah and Marselan, but riper grapes of Tannat had higher proportions of p-coum. (increased from 14 to 18%) and lower of Fer. (from 5% to 2%). In wines, Syrah had lower HCA contents (127 mg/l-152 mg/l) than Marselan (252 mg/l-317 mg/l) and Tannat (178 mg/l -328 mg/l). The wines made from the riper grapes had higher HCA contents in Tannat and Syrah, while lower in Marselan. In the 3-month wines, the main HCA was Caff. (more than 70% in all cases), followed by p-coum. (15% in average) and Fer. (between 4%-5%). Syrah wines had lower proportion of Caff. and higher of p-coum. than Marselan and Tannat. During wine storage, p-coum. proportion increased while that of Fer. and particularly Caff. decreased denoting the higher reactivity of the later, consistent with its molecular structure.

Hydroxycinnamic acids in grapes and wines made of Tannat, Marselan and Syrah from Uruguay

Abstract

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