I spent most of a recent rainy afternoon researching yeast and I came across so many pages of information, I quit after the ‘L’s. So I’ll boil it down to some essentials. It’s easier to digest that way.
Yeast is necessary component in fermentation process, and is added to the juice when in the barrel or fermentation vessel. It melds with the sugar in the juice, producing heat to convert sugar to alcohol. This reaction continues until the yeast dies off. Fermentation ceases, and we have wine. The end.
Okay, maybe I oversimplified there.The type of yeast is also important: yeast is generally selected for both the amount of alcohol content it will produce, and the taste it will create. It can come from two main sources: ambient (wild) or commercial.
Bloom ~ refers to the pure or native yeast strain found on grape skins, and a common view is that to produce a truly indigenous wine, thus expressing terroir, one can only use wild yeast. A problem exists when using ambient or wild yeast: very few can consistently reproduce the qualities a wine maker is looking for. Where commercial yeasts win is that they are incredibly reliable and make it easier to control the outcome of the end-product.
For some purists, adding commercial yeast disrupts the ‘expression of terroir’ in a wine. That’s fair enough, I guess, but I’d imagine that to be easier to control if you’re making very small quantities of very specific wine, that’s going to a very limited customer; like your Aunt Lorraine. Most wineries, cottage or otherwise, have to answer the call of supply and demand, moreover, must address consistent quality issues. That is something that wild or native yeast can’t regularly deliver.
Terroir or no terroir, the last thing a winemaker needs, at the end of the day, are bottles of undrinkable wine coming back from the consumer.
What I want to know is: does the yeast go in before or after your feet?