Wine Arcana

Concept

Grape ripeness and harvest decisions

Grape ripeness is the condition of the fruit in relation to the wine a grower and winemaker intend to produce. Sugar, acids, aroma compounds, skins, seeds, and fruit health change together, but at different rates. Harvest selects a point in that changing balance.

Fruit suitable for a sparkling base wine may be picked before fruit destined for a fuller still wine from the same variety. Grapes intended for a botrytized sweet wine follow another path. There is consequently no universal harvest date or sugar reading that defines ripeness for all wines.

What changes after véraison

At véraison, berries soften and begin the main ripening phase; dark-skinned varieties develop colour. Sugar accumulates as the vine supplies the fruit, while malic acid is consumed in metabolism. Tartaric acid behaves differently, so the changing acid balance depends on more than the loss of one compound.

Aroma compounds and their precursors also develop. Some green-smelling components decline, while other compounds accumulate or become available for transformation during fermentation. The direction and timing depend on the variety and growing conditions. For red wines, growers also assess colour development, skin properties, and seed maturation.

Measurements and tasting

Degrees Brix measures soluble solids and is commonly used to estimate sugar and potential alcohol. It is an estimate: Oregon State University notes that Brix is not identical to fermentable glucose plus fructose, and that sample preparation can change the reading.1. James Osborne, Oregon State University Extension, “Preparing for harvest: Grape chemistry and prefermentation adjustments,” sections on sampling, Brix, and acid measurements.

Growers also measure pH and titratable acidity, which describe different aspects of acidity. Tasting berries adds information about flavour, texture, and uneven development. Representative sampling is needed for both tasting and analysis.

A useful sample includes different parts of the block, both sides of the row, and berries exposed to different conditions. Repeating the sampling shows the pace of change. Picking only appealing berries can make a vineyard seem more advanced than the fruit that will actually arrive at the press.

Water, heat, and fruit health

A rising sugar concentration can reflect both sugar accumulation and loss of berry water. Shrivelled fruit therefore needs interpretation. Severe water stress can restrict photosynthesis, while high temperatures can accelerate acid loss or damage exposed berries. Additional time on the vine does not guarantee continued improvement.

Waiting also changes exposure to rain, rot, birds, and autumn frost. A sound crop picked before a storm presents a different starting point from damaged fruit harvested later at a higher Brix. Vineyard access, available labour, transport, and winery capacity influence what can be picked and processed promptly.

Different endpoints for different wines

Chenin Blanc makes the range of objectives easy to see: earlier fruit can supply sparkling wine, later fruit still wine, and concentrated berries sweet wine. For Cabernet Sauvignon, a grower may weigh herbal aroma, tannin extraction, alcohol potential, and forecast weather together.

These decisions continue into the cellar. Pressing, skin contact, fermentation, and blending shape the material harvest provides.

Sources