Has the moment to snip arrived?
It's harvest season in the northern hemisphere. Thousands of winemakers are sharpening their secateurs hoping they get the moment right. All will taste the grapes – ripe & sweet? sour & acidic? – to snip or wait, that is the question. As Jon Bowen, winemaker at Domaine Sainte Croix states: “It’s the single most important decision in the winemaker’s calendar”. The greatest contributing factor to the style and quality of the wine. In our post-industrial age is easy to forget that nature does a damn good job providing for us.
Grape composition & ripening
“The grape is a self-contained winemaking machine” says scientist Grady Wann at UC Davis. It not only has the sugars to ferment into alcohol, but acidity to balance flavour and host yeast to kickstart the process.
Before the monks discovered this magical machine, like most fruit, the design (colour, taste, pips) enticed birds to eat, digest, and poop the seeds of tomorrow’s vine (in a healthy dollop of manure). A self-reproduction system. Ripening in the hot summer sun triggers several reactions on the vine that fall into two distinct processes: sugar ripening that we can see (the grape skin changes colour) and taste with sugar accumulating and acids mellowing, Farmers also use a refractometer to measure sugar concentration and therefore alcohol %.
The second, more complex chemical process is termed ‘phenolic ripeness’ and follows its own trajectory – this is nature’s elusive flavour enhancer, and the two chemical processes are not synchronised. Scientists have limited molecular understanding of this phenomenon so the farmer evaluates phenolic maturity – colour pigments (anthocyanins), phenolics (those tannins) and other flavours specific to the terroir – with experience, nous and for some, the pips. Have they softened? Are they woody? Those adored secondary flavours bringing complexity and lots of fanciful adjectives.
Grape chemistry & flavour
Chemistry. To capture the impact on flavour of the ripening dilemma – too early or too late – I feel the need to tabulate. It’s nowhere near this neat in nature, so here’s what we know is going on in the veraison stage:
With sugars rising and acids reducing it’s the phenolic phenomenon that transforms alcoholic grape juice into the majestic subject of wine.
The art of the decision & getting it right
If the chemical activity within each vine is not complicated enough, there are factors that vary plot-by-plot:
- Temperature – a scorching summer speeds ripening
- Altitude – cold nights lengthen the ripening cycle, enhancing flavour
- Grape varietal – varies by grape, especially non-indigenous
- Soil type, etc, etc.
With all these variables, flavour development and the texture of the tannins is evaluated by the farmers’ long-earned intimacy with the terroir. When harmony between sweetness / acidity / phenolic ripeness is pinpointed, the moment to snip has arrived.
Teamwork
Harvesting is a team sport. Early rise. Hand-harvesting. Small crates. Ton-after-ton. Back-breaking work. Getting the grapes to the cellar quickly allows the winemaker to get out of nature’s way and eek the flavours from this ‘self-contained winemaking machine’. The winemaker marks this moment with an end-of-harvest lunch party, the shenanigans of which, remain legendary.
