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Advisor(s)
Abstract(s)
The timing of the grape harvest is a critical decision for winemakers, as it greatly impacts the quality and
organoleptic characteristics of the resulting red wines. One key indicator for determining the optimal harvest
time is the phenolic content of the grapes. As the berries ripen, phenolic compounds in the grape skin cells
migrate from the seeds to the pulp and finally to the skin. However, monitoring these phenolic changes,
particularly in the seeds, presents a challenge. This research addresses this problem by developing a novel
technique to track the phenolic composition of seeds during ripening. The objective is to provide a reliable
method for winemakers to monitor the phenolic evolution and improve harvest decision-making.
In this study, a multisensory system consisting of four electrochemical enzymatic carbon paste sensors,
modified with tyrosinase and electrocatalytic materials (AuNPs, lutetium phthalocyanine, and nickel oxide
nanoparticles), was employed to analyze the phenolic content in grape seed extracts. The system monitored
weekly changes in the phenolic composition of the seeds from three red grape varieties—Cabernet Sauvignon,
Tempranillo, and Prieto Picudo—during their ripening from veraison to being overripe. Using voltammetric
techniques, the electrochemical responses were characterized by shifts in peak positions and intensity changes,
reflecting the oxidation/reduction of phenols. Principal Component Analysis (PCA) demonstrated the ability of
the array of sensors to discriminate phenolic changes across ripening stages, while Partial Least Squares (PLS)
regression provided robust correlation models between the electrochemical responses and seed phenolic content,
with correlation coefficients ranging from 0.93 to 0.99. The developed methodology successfully tracked
phenolic changes, offering a promising tool for monitoring grape seed maturation and assisting in determining
the optimal harvest time.
Description
Keywords
CPE Gold nanoparticles Metal oxide nanoparticles Phthalocyanine Phenolic maturity Grape ripening
Pedagogical Context
Citation
Garcia-Hernandez; C.; Perez-Gonzalez; C.; Martin-Pedrosa; F.; Dias; L.G.; Barajas-Tola; E.; Rodriguez-Mendez; M.L.; Garcia-Cabezon; C. (2025). Looking for the optimal harvest time of red grapes with an enzymatic electrochemical multisensory system. Journal of Agriculture and Food Research. ISSN 2666-1543. 19, p. 1-11
Publisher
Elsevier