Observation of Spontaneous Maturation Process of Young Wine by Application of the Voltammetric Quadruple Disk Iridium Sensor Combined with Chemometrics

Abstract

This paper describes a straightforward strategy, which enabled monitoring of the natural young wine maturation and calculation of the time elapsed since the harvest. Samples of four natural young wines from the Polish vineyard have been measured during the period of late fermentation (day 14th and 35th since the harvest) and early maturation (day 54th, 119th and 229th since the harvest). Wine fingerprints were recorded by differential pulse voltammetry (DPV) using a quadruple disc iridium electrode (q-DIrE). Principal component analysis (PCA) and partial least squares (PLS) regression distinguished wines at each stage of maturation and enabled determination the time passed since the start of winemaking process. The best results provided the PLS models for each of the wines separately, with a prediction error of 2.04−3.24 days and correlation (R2 Pred) ranging from 0.9989−0.9994. The more universal model, based on all wine samples, delivered also satisfactory results with RMSEP 4.13 days and R2 Pred equal to 0.9970. The experiments also showed that even short-term storage under various conditions clearly changed natural wines, and these changes can be observed using the voltammetric signal and PCA.