Application of a low-cost device VIS-NIRs-based for polyphenol monitoring during the vinification process

Abstract

In red wine production, phenolic maturity is becoming increasingly important. Anthocyanins, flavonoids and total polyphenols content and availability significantly influence the harvest time of wine grapes while, during vinification process, their extraction strongly affects wine body, color and texture. The polyphenol presence in musts and wines, over that by the grape berry accumulation and the cellular maturity, is significantly influenced by maceration and fermentation techniques. To date, polyphenol evaluation is performed using destructive, laborious, expensive and often environmental unfriendly methods of analysis. Nowadays, companies that want to be competitive in a global market must necessarily undergo to a process of innovation and digital transformation. In this context, the GO-SmartData project (smart management of vineyard and cellar) aims to identify a rapid, economical, easy-to-use and non-destructive technologies for monitoring fermenting musts and wines. Here, the application of a low-cost mini-sensor based on Visible and Near Infrared (VIS-NIR) spectroscopy designed to operate into 19 selected spectral bands between 410 and 1720 nm is proposed. The prototype is designed to collect, directly from the wine tanks, data to be send to an in-cloud system (IoT) and computed into numerical values, according to predictive statistical modelling. The spectra detection through the VIS-NIR prototype has been performed on fermenting musts and aging wines concomitantly with analytical measurement of polyphenols. Predicting models were built using multivariate regressive approaches (PLS) which were then tested for accuracy and robustness in terms of correlation (R2), as well as potential errors (RMSEC, RMSEP). The VIS-NIR prototype shows quite promising performances and aptitudes for becoming an easy-to-use device destined to the on-line employment in the vinery environment