In-line Monitoring of the Winemaking Process: Redox Variables and Antioxidant Power

In-line monitoring of the winemaking process with a limited number of variables remains a current challenge in wine research, aiming to provide rapid assessment of wine stability, oxidizability, and precise dosing of additives or adjuvants. Two key variables related to wine redox status are redox potential (ORP) and antioxidant power (AP), poorly monitored during wine production due to the complexity of oxidation phenomena, the difficulty of performing current AP assessment tests directly in the winery, and the challenges in measuring and interpreting ORP. This study applied a rapid AP test, the wine antioxidant test (WAT, based on Fe3⁺/ Fe2⁺), and an in-line multiparameter system for monitoring temperature, ORP, and dissolved oxygen (DO) during fermentation/maceration of Sangiovese red grapes (at 25°C, with replications), to understand the correlation between these variables and propose a new approach for in-line assessment of wine production. ORP and Bold type indicates presenting author Wednesday National Conference Oral Presentation Abstracts (Research Papers) 2025 NATIONAL CONFERENCE TECHNICAL ABSTRACTS47 WEDNESDAY ORAL ABSTRACTS JUNE 16-19, 2025 | MONTEREY, CALIFORNIA DO were measured continuously with probes, while WAT and DPPH were measured daily. Wine color and polyphenol content were analyzed using spectrophotometric indices, CIELab, and high-performance liquid chromatography-diode array detection. ORP was able to describe the evolution of alcoholic fermentation and polyphenol extraction, for the experimental condition applied. All parameters monitored during fermentation/maceration were used to create a predictive model for the AP measured by WAT (R2 0.97 for the calibration model and R2 0.76 for the validation model). In particular, WAT results correlated directly with wine polyphenol content, DPPH, and polymeric pigments, and indirectly with ORP. ORP, in turn, correlated with monomeric anthocyanins (R2 0.9013), polymeric pigments (R2 0.9013), DPPH (R2 -0.8210), and DO (R2 0.9759). This study opens new avenues for research in the field of precision enology, supporting the development of in-line winemaking control.