Colour characterisation of two‐year‐old Pinot noir wines by UV–Vis spectrophotometry and tristimulus colourimetry (CIELab): Effect of whole bunch or grape stems addition.

This article investigates the impact of including whole bunches or grape stems during fermentation on the colour development of Pinot noir wine. Five winemaking treatments varying in stem inclusion—destemmed grapes only (DS), 30% whole bunch (WB30), 60% whole bunch (WB60), 100% whole bunch (WB100), and destemmed grapes with 100% stems added back (DS100)—were analyzed at the end of alcoholic fermentation and after two years of bottle ageing using the modified Somers assay and CIELab colour measurement. Results showed that stem inclusion increased tannin concentration and hue while significantly reducing total anthocyanins, especially in treatments with higher stem proportions; however, differences in anthocyanin levels diminished after ageing due to pigment polymerization and degradation. CIELab analysis indicated that wines with high stem inclusion exhibited less red colour (lower a*) and more brownness (higher hue angle) after ageing, suggesting that stem addition may accelerate visual ageing effects in Pinot noir. These findings provide winemakers with insights into how whole bunch or stem additions influence both short-term and long-term colour characteristics in Pinot noir wines.