Wednesday, 15 October 2014

A little chemistry lesson for a story teller at harvest time

Pressing the grapes skilfully at harvest time is the single most important stage in champagne-making. Get that right and everything else should flow smoothly afterwards. "Flow" is the operative word, for a careful monitoring of the juice, as it moves along the pipe from press to vat, gives the winemaker a precise pointer to the juice's purity, structure & quality - or otherwise, not least when these positives  fade towards the end of the final pressings.

 We are into a very technical area. Happily, a clear explanation of the science comes from Philippe Thieffry, senior winemaker of Veuve Clicquot, formerly at Henriot, where he created the magnificent  prestige Cuvée Les Enchanteleurs. Philippe stresses that "on the subject  of the measures like connectivity, carried out on the "must", what this is about is in fact CONDUCTIVITY. This measure appreciates the richness in minerals of the juices, of which potassium is the most important. The more ions (atoms with an net electric charge) there are, the more conductivity will be raised and the more the juice will be the conductor." It's also worth noting that conductivity and of course pH are at their highest on the juice at the end of the pressing (tailles). That end-juice is clearly less stable and will be used, one hopes sparingly, in  budget non-vintage champagnes for quick consumption.

" Conductivity is also employed  to appreciate the stability of  wines vis à vis tartaric precipitations - by calculating the temperature of saturation  of the wine through a differential measure of conductivity before and after saturation of the wine with tartaric acid," Philippe concludes.

That's quite enough science for one session. If you prefer a more artisanal approach, you will be reassured by the advice of one outstanding chef de caves, who as always thinks outside the box. "  Don't get preoccupied with the science. Traditionally, the most careful champagne-makers taste the   juices constantly throughout  the pressings to gauge their purity and balanced richness appropriate to  a classic Cuvée ( first two 'serres') ". The palate of an experienced press manager may be the surest  test of all.

I am very grateful also to Manu Fourny, Guillaume Roffian, Laurent Champs and Arnaud  Margaine for their approaches to pressing. And not least to my friend and colleague Anne Krebiehl MW for   urging me to ask them the right questions!  

PS. This post is offered as a rider to my "Pressing Matter revisited" feature  published in the October issue of the Drinks Business. I hope  the issues are now clear to the reader.