Thank the microbes for your favourite wine

(TimesColonist) - We rarely see grapes being crushed by foot these days, but visitors to the Cowichan Wine and Culinary Festival this month witnessed an old-fashioned grape stomp. Seven teams, dressed in costume, with grape juice soaking the hems of their trousers, shorts, gowns and dresses, competed against each other to stomp the grapes the fastest.

Their bare feet and enthusiasm served to remind spectators of wine making’s fundamentals.

The making of wine, here and everywhere, starts with sun, water, a bit of soil and vines that take all of the above and turn them into the purple, red or green globular clusters we call grapes. Those who tend the vines and those who transform the grapes into wine strive to create a product that represents and reveals all the most desirable qualities of the fruit, the place, the climate and so on. Each resulting bottle contains a bit of the heart and soul of the land and of the people who work it.

Yet, behind the growers of grapes and makers of wine, other players call the shots. In the most basic sense, microbes make the wine.

Yeasts turn grape juice into wine through fermentation, and in most red and some white wines, bacteria complete the process with a second fermentation that mellows flavour and keeps the wine from going fizzy in the bottle. Growers and vintners shepherd and shape the process that turns sunshine and water into wine, but micro-organisms do the heavy lifting. They determine flavour, alcohol content, feel and, well, success of the resulting beverages.

Humans have sought and savoured wine for thousands of years, yet fewer than one per cent of the estimated 700,000 strains of wine yeast worldwide have been identified. This knowledge gap leaves the potential of most strains undocumented and untapped. It also puts important but lesser-known strains at risk of disappearing as use of industrial wine yeasts becomes standard.

But scientists and wine technologists are working to remedy that. For instance, researchers recently catalogued more than 200 strains unique to just seven wineries in Sicily. The scientists — Italians all — tested the native strains against industrial wine yeast, using two previously undocumented local strains to make wine from local grapes. They found the local yeasts outperformed industrial wine yeasts, creating flavourful, high-quality wines that, according to industry experts who blind-tasted the wines, captured and preserved the local grapes’ character better than the industrial yeasts did.