Screening of Wine Extractable Total Phenolic and Ellagitannin Contents in Revalorized Cooperage By-products: Evaluation by Micro-NIRS Technology

Abstract

Determining phenolic compounds of wood and its extractability to the hydroalcoholic medium is important in the oenological industry. The method proposed in this study copes with this issue in an in situ, non-destructive, and fast way. For this purpose, a number of oak by-product samples spectrally representative have been selected. Selected spectral data have been correlated with oak wood extractable polyphenols (extractable total phenolic content and extractable ellagitannin content) by modified partial least squares regression (MPLS) obtaining coefficients of determination (RSQ) greater than 0.9 and standard errors of prediction (SEP) between 13.68 and 23.51% for all parameters evaluated. The obtained results are comparable with those obtained using bench-top devices and present the advantage of its eventual friendly use out of lab. Development of applicable models in situ will allow a greater versatility and efficiency for the decision-making in the winemaking process on the adequacy and/or dosage of these by-products according to the requirements of the wine. The use of cooperage by-products as the source of copigments for wine leads to a sustainable and competitive cooperage industry, through waste reduction and by-product valorization.