Ellagitannins in wines: Future prospects in methods of analysis using FT-IR spectroscopy

Abstract

Wine aging in wooden barrels can alter a wine's sensory features through the extraction of wood phenols such as lignins, volatile phenols and hydrolysable tannins. Among the hydrolysable tannins, ellagitannins have been found not only to modify a wine's sensory character but also to generate new products with compounds already present in wines. For this reason, their quantification is of high importance. However, ellagitannin analysis requires the use of sophisticated equipment and many preparative steps, making their quantification in wines cost effective and laborious. In this study, the feasibility of FT-IR spectroscopy coupled with chemometrics for the quantification of ellagitannin concentration in wines was examined for the first time. Partial Least Squares regression was used to construct calibration models, using the fingerprint region of the spectrum, 1821-950 cm−1 (first derivative in range). The correlation coefficient (R2) was found 0.93, the Root-Mean-Square Error of Calibration RMSEC was 1.17 and the Root-Mean-Square Error of Prediction, RMSEP was 1.57. The results indicate that FT-IR could be used for a quick, non destructive and economical estimation of a wine's total ellagitannin content.