Anthocyanins composition and extraction from Grenache noir (Vitis vinifera L.) vine leaf using an experimental design II- by ethanol or sulfur dioxide in acidified water

Abstract

Aim: Anthocyanins are water soluble pigments located in grape skin as well as in vine leaves. The aim of this work was to identify, and determine the anthocyanin composition in Grenache noir (Vitis vinifera) leaves as well as to estimate the optimum conditions leading to the highest anthocyanin extraction yield.

Methods and results: Five anthocyanins were identified and quantified in Grenache noir leaves by HPLC-DAD-MS. Among these anthocyanins, cyanidin-3-O-glucoside and peonidin-3-O-glucoside were the main anthocyanins, representing 43 and 38 %, respectively, while delphinidin-3-O-glucoside, petunidin-3-O-glucoside and malvidin-3-Oglucoside accounted for only 6, 5 and 8 %, respectively. To estimate the highest anthocyanin extraction yield, a multi-factorial design experiment was used to build a mathematical model. The extraction conditions tested were time, temperature and solvent composition (i. e., ethanol or SO₂ level in acidified water).

Conclusion: Only the five mono-glucoside anthocyanins usually detected in grapes have been detected, identified and quantified in Grenache noir leaves. The optimum extraction conditions of these anthocyanins were obtained for acidified hydro-alcoholic solution (i. e., pH 2, 3 h, temperature ranging between 36.5 and 40 °C and an ethanol concentration ranging between 36.8 and 40 %) and for acidified water with SO₂ (i. e., pH 2, between 5.8 and 6 h, a temperature ranging between 38.6 and 40 °C and a concentration of 500 ppm of SO₂).

Significance and impact of the study: Five mono-glucoside anthocyanins were identified and quantified in Grenache noir leaves. The optimum extraction conditions for of these anthocyanins were estimated in acidified hydroalcoholic solution and in acidified water with SO₂. These extraction procedures will allow further investigation of the potential use of these anthocyanins as natural pigment for food as well as for the pharmaceutical and cosmetic industry.