Welcome to our new monthly section, where we will be demystifying and explaining some of the more technical aspects of wine and winemaking, all within the context of how we do things here at Oldenburg Vineyards. As we approached harvest, we sat down with Nic to learn more about exactly how he makes one of the most critical decisions: when do we pick? To determine the precise time to harvest, the team considers historical data (looking back at past seasons gives a good idea when blocks typically ripen), the climatic conditions of the season (this takes into account the season from bud-break to flowering and into ripening).
Around two weeks before ripening, the team walks through the blocks doing random sampling: one berry is taken from one row (at the top of the bunch), then further down the row, another berry is taken from the opposite row (from the middle of the bunch), and further down again another berry is taken from the first row (from the bottom of the bunch).
They continue until they have about 200 berries picked. The sample is taken back to the cellar, crushed, and the sugar is measured using a density meter (Balling meter). We determine the g/L of sugar in the grapes, which is an indication of ripeness. Sugar levels are not the only determining factor, though. Nic tastes on a combination of sugar as well as the overall flavours. He can also extrapolate the alcohol percentage based on the sugar levels, to ensure the percentage won’t be too low or too high.
As the grapes approach ideal ripeness, Nic does a lot of tasting as he walks through the vineyards, to evaluate the overall flavour profiles. He also physically examines the grapes, looking for the signs of physiological ripeness. For example, change of colour (for white grapes, yellowing of the green skin; for red grapes, a deep red colour) also, turgidity (defined as “a state of being turgid or swollen” – meaning the berries are plump with water) as well as evaluating the ripeness of the pips. When the berries are not ripe, the pips are green and impart an undesirable astringency. When they are ripe, the pips turn brown and crunchy and lose that overt astringency. When all the factors align, the grapes are harvested, and a new vintage begins.