Feasibility assessment of a low-cost near-infrared spectroscopy-based prototype for monitoring polyphenol extraction in fermenting musts.

Abstract

Background: The winemaking industry increasingly relies on non-destructive techniques to support processing activities, particularly in response to climate change-induced imbalances between technological and phenolic grape maturity. Spectroscopy-based instruments have become widely available for monitoring key parameters such as total polyphenols, anthocyanins and tannins during maceration and fermentation. Near-infrared (NIR) spectroscopy presents a promising solution for rapid and efficient analysis, potentially enhancing process control and decision-making in winemaking.

Discussion: This study evaluates the feasibility of a low-cost NIR spectroscopy-based prototype for monitoring phenolic extraction in small-scale fermentations. The device's performance was assessed by correlating spectral data with conventional reference measurements, including total polyphenol index, tannin concentration, colour intensity, anthocyanins and polymeric pigments. Predictive models were developed using partial least squares regression and compared with those obtained from a commercial Fourier transform (FT)-NIR spectrophotometer to assess the prototype's accuracy and reliability.

Conclusion: The results indicate that the low-cost NIR prototype shows potential for monitoring phenolic extraction during fermentation, providing real-time and non-destructive measurements. While its predictive performance was slightly lower than that of the commercial FT-NIR system, the prototype demonstrated promising accuracy, suggesting that with further optimization it could serve as a cost-effective alternative for wineries seeking rapid and affordable phenolic analysis. © 2025 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.