Optoelectronic sensor device for monitoring the maceration of red wine: Design issues and validation

• We report an optoelectronic instrument featuring LEDs and photodiodes.
• The system determines the chromatic characteristics of grape must during fermentation.
• Color intensity, hue and brightness are calculated from absorbance measurements.
• Wavelengths of interest are 420, 520 and 620 nm.

Enologists usually rely on spectrophotometers to perform the chromatic characterization of red wines. This work reports an optoelectronic instrument based on absorbance measurements aiming not only at the assessment of the chromatic characteristics of finished red wines, but at the supervision of the gradual maceration of fermenting grape musts as well. Maceration is a chemical process that takes place during the early stages of the fermentation that finally results in red wine. It is through maceration that wine acquires its distinctive chromatic features. Key issues related to the selection of optoelectronic components, the system design and its final validation using diluted wine samples are thoroughly discussed. Resolution figures lie in the range of one thousandth of an absorbance unit. Maceration has been successfully monitored with the proposed instrument using grape must samples extracted during the first three days from two different fermentations.