Grape varieties ripen at slightly different times and in Matakana, this occurs between late March and late April. The decision as to when to pick is determined initially by taste and examination of the berry pips and bunch stems, backed up by measurements of sugar and acid levels in the fruit. These are based on juice analysis from a randomly selected sample of berries. The acid in grapes drops as sugar rises, and the rate of each is determined by the weather. Because we want to avoid too much or too little of either, the winegrower’s skill is in deciding exactly when both are optimal.
When this occurs the grape picker’s skill comes into play. Many local people have worked at grape picking for some years now, so there is a pool of experienced grape pickers in the district. Picking is not as simple as it may seem – selecting the right bunches and discarding those which are either “second set” (unripe), or have signs of rot, is not always obvious and takes skill and judgement. The bunches are picked into small bins then transported to the winery.
The processing procedure depends upon whether the grapes are white or red. The colour in red wine comes entirely from grape skins, which along with the pips contribute flavour and the tannins. These are essential to give red wine its structure and stability so the red juice, pulp, pips and skins are all kept together. White wine is a more delicate beverage, so skins, pips and pulp are discarded and only the juice is fermented.
At this point, the winery workers really get going. Bunches are fed into a de-stemmer/crusher, a machine which removes the stems then crushes the berries. This produces a slurry of juice, skins, pips and pulp, called “must”. Red must is pumped directly into a large open-topped fermenting tank. White grapes are also de-stemmed and crushed, but white must is then pumped into the wine press. This allows the “free run” juice to drain, then squeezes the skins and pulp to extract the remaining juice.
The must can then be inoculated with yeast. Put simply, fermentation is the consumption of grape sugar by yeast, the main product of which is alcohol. During fermentation the winery workers need to be continuously monitoring the progress of the ferments in a range of ways, adding yeast nutrient if necessary, adjusting refrigeration temperature on white wine tanks so the must stays relatively cool, and regularly “plunging” or “pumping over” the red tanks to keep the raised cap of skins moist and healthy, and to assist colour extraction from the skins.
This means hard and unrelenting physical work, right through the night for the three to five days which it typically takes a red must to complete fermentation, and for very long hours during the remaining weeks of the vintage period. There is no family or social life for the winery worker at this time of year – cellar hands are wedded to their ferments!
None of this acknowledges the biochemical magic which happens when grape juice becomes wine – but maybe the explanation of such magic is best left to Plato, who said around 2400 years ago: Nothing more excellent or valuable than wine has ever been granted by the Gods to man. Amen to that.
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