Whole-Bunch (Whole-Cluster) Fermentation

Conventional red winemaking destemps grapes before fermentation — the stalks are removed because unripe stalks add harsh, green tannins. Whole-bunch fermentation includes some or all of the grape clusters, stems and all, in the fermentation vessel. When the stems are fully ripe (lignified — woody and brown rather than green), they add spicy, savoury complexity, natural cooling to the fermentation, and oxygen permeability to the mass of grape skins, which can produce finer, more integrated tannins.

If stems are not fully ripe, the result is the opposite — grassy, green, vegetal flavours and astringent tannins. The technique therefore requires excellent grape maturity.

Whole-bunch fermentation is associated with traditional Burgundy Pinot Noir (where it can add spice, structure, and complexity), some Syrah from the Northern Rhône, and natural wine producers. In Burgundy, the proportion of whole clusters varies by producer and vintage — some producers use 100% whole bunches for Grand Cru wines.

At Level 3, candidates should explain both the benefits (complexity, spice, structure) and the risks (green tannins if stems are unripe) of whole-bunch fermentation.