Monitoring the tawny port wine aging process using precision enology

AIM: Tawny Port wine is produced in the Douro Demarcated Region by blending several fortified wines in different aging stages. During the aging process in small wood barrels, the red wine color progressively develops into tawny, medium tawny, or light tawny. In this Port wine style, there are some special categories like Tawny Reserve, Tawny with Indication of Age (10, 20, 30, and 40 years), and “Colheita” that are commercialized worldwide. This last category is an exception, as these wines are from a single vintage [1]. In Tawny Port wine the oxidative aging process is multifactorial and critical for reaching the required quality. So, real-time monitoring of important intrinsic and extrinsic factors known to impact both wine quality and aging time are important to optimize and to manage the natural inconsistency among wines aged in diverse long-used wood barrels. This work shows the design, development, and implementation of a remote distributed system to monitor factors that are identified to be critical for the Tawny Port wine aging process.

METHODS: The Tawny Port wine aging process was monitored in two equal wineries – one of them with controlled temperature– in Vallegre, Porto S.A.. Barrels were instrumented with sensors to measure parameters during the aging process, specifically: pH, redox potential, dissolved oxygen, and temperature. The monitoring process was done using an RS-485 industrial network, which interconnects the mentioned sensors [2].

RESULTS: The distributed monitoring system was capable to detect differences among barrels and among the different storage conditions (controlled and room temperature). Redox potential and dissolved oxygen were the wine’s parameters where the differences among the different barrels were higher under the same storage conditions. Since the Tawny Port wine aging process is oxidative, a variation in the wine’s aging process among barrels is to be expected. Significant differences were detected in the oxygen consumption rate among the different barrels. Differences in the phenolic composition were also observed in the aged wine, both at controlled and room temperature.

CONCLUSIONS: Results indicated that the distributed monitoring system was capable to detect variations among barrels and among both storage conditions: controlled and room temperature. Actually, redox potential and dissolved oxygen were the wine’s factors where the variances found were higher among wood barrels, while under the same storage conditions. This methodology is based on easy-to-use implanted systems, with the intention of giving an important contribution to other projects in the area of precision enology.

The authors want to acknowledge FCT Portugal for funding the CQ – VR through the grant (UIDB/00616/2020 and UIDP/00616/2020), to project INNPORT “Otimização do processo de envelhecimento do vinho do Porto Tawny” and Vallegre Company.

Email: fcosme@utad.pt

Keywords: precision enology, wine aging, instrumentation

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