Pulsed electric field treatment to improve the phenolic compound extraction from Graciano, Tempranillo and Grenache grape varieties during two vintages

Résumé

The aim of this work was to study and compare the effect of pulsed electric field (PEF) treatment on the content of individual anthocyanins, phenolic acids, flavanols, and flavonols of three grape varieties from two vintages. For this purpose, the treatment showing to induce the highest release of phenolic compounds out of four different PEF applications assayed during the 2011 vintage was applied in 2012. The same continuous system was used over three grape varieties: Graciano, Tempranillo, and Grenache. Additionally, the influence of PEF on the physicochemical composition of the grapes was also studied. The effect of PEF treatment in the amount of individual phenolic compounds released and in the values of the physicochemical parameters analysed was qualitatively similar yet quantitatively different between the two years of study. Considering that the initial values of the physicochemical parameters were dependent on the vintage, it was observed that the lower the initial values the higher their increase after PEF treatment. Hence, the lower the initial values the higher the benefit obtained by PEF treatment. Furthermore, the influence of PEF treatment depended on the variety treated. For instance, Tempranillo was the variety showing the most significant differences in the content of individual anthocyanins upon PEF treatment, while Grenache variety showed major differences in the content of gallic acid, catechin, and epicatechin. Graciano variety showed almost no differences in the amount of individual phenolic compounds released after PEF application. For the three varieties, colour intensity, TPI, and total anthocyanins were increased by PEF application during the two assayed vintages, as well as antioxidant activity in 2012. Industrial relevance Pulsed electric field treatment is a suitable technology for the extraction of phenolic compounds. However, its suitability depends on the grape variety treated, and its quantitative effect depends on the initial phenolic composition of the grapes. Consequently, this technology could be used in the food industry to enhance the healthy properties of must and wine. © 2015 Elsevier Ltd. All rights reserved.