Low-cost non-destructive sensors for monitoring polyphenols, volatile compounds and quality parameters in grapes, musts and wines
Author(s)
Alfieri, Gianmarco
Date Issued
September 29, 2025
Type
Doctoral Thesis
Abstract
Climate change is increasingly affecting the compositional characteristics of grapes, leading to an anticipation of technological ripening in relation to phenolic ripening and making it more challenging to produce balanced, structured, and long-lived wines. In this context, the availability of rapid, non-destructive, and cost-effective tools for monitoring phenolic compounds during winemaking becomes crucial to support timely and informed oenological decisions. This research addresses this need by exploring the development and application of prototype sensor technologies for the measurement of polyphenols in modern enology, with the aim of providing effective tools to mitigate the impact of global warming on wine quality. Furthermore, the rapid monitoring of key analytical parameters in fermenting musts has long been considered a hallmark of quality in the winemaking process, allowing producers to promptly intervene in case of issues arising during vinification.
Three low-cost prototype devices were designed and tested: a spectrophotometer operating in the visible (VIS) region, one in the near-infrared (NIR) region, and a quartz crystal microbalance with dissipation monitoring (QCM-D) sensor functionalized with selective peptides. The VIS-based spectrophotometer was employed to non-destructively monitor phenolic extraction during skin maceration in red wine production. Trials were carried out on three grape varieties subjected to different fermentation protocols and validated through parallel destructive chemical analyses. Results demonstrated the potential to develop predictive models for key parameters such as anthocyanins and total polyphenols, although limitations in robustness and sensitivity were observed, likely due to the reduced spectral resolution and limited UV range coverage.
To address these limitations, a second prototype was developed based on NIR spectroscopy, capable of providing more comprehensive information on the wine matrix’s chemical-physical structure. The use of the NIR region significantly improved the predictive capacity of the system, enabling more accurate estimations of polyphenol content and phenolic ripeness indices. This approach proved more suitable for operational deployment, thanks to enhanced response stability and the ability to collect real-time data without sample preparation. The implementation of
chemometric models further enhanced the device’s capacity to accommodate the natural variability of grapes and fermentation conditions.
In parallel, a completely different technology was explored, based on QCM-D sensors functionalized with synthetic peptides designed to selectively interact with specific classes of phenolic compounds. This system allows for label-free analysis with high molecular specificity, while maintaining the non-destructive nature of the measurement. Laboratory tests demonstrated the sensor’s ability to selectively recognize phenolic acids and flavonoids, offering a novel perspective for advanced qualitative monitoring of tannins and their evolution. However, challenges remain in terms of signal reproducibility and functionalization stability, requiring further optimization of surface chemistry and operating protocols.
Additional information
Dottorato di ricerca in Scienze, Tecnologie e Biotecnologie per la Sostenibilità
File(s)![Thumbnail Image]()
Name
galfieri_tesid.pdf
Size
2.99 MB
Format
Adobe PDF
Checksum (MD5)
8deab1facad19297639c7d43f70c26a6