[Sca-cooks] Verjus

[Edouard de Bruyerecourt]

Wanda Pease wrote:

>I have a Thompson seedless grape in the back yard, originally planted in
>about 1945.  I tried picking the grapes and mashing them in a conical sieve
>then letting the juice drip and putting it into a freshly scalded crock
>which was allowed to sit in a cool place for a couple of weeks.  It didn't
>seem to ferment much, but it did mold.  Next batch went into the crock for a
>couple of days with scalded cheese cloth over the top, then into the fridge.
>Was tasty and tart.  I'll have to get a bottle of the labeled stuff to see
>if they are anything alike.
>
>Regina
>
My understanding is wild yeast (and possibly other microbes) are on the 
grape skin, that they are the white bloom coating on grapes. Basically, 
breaking the skin starts fermentation. And grape juice as just the right 
amount of sugars, pH level, and nutrients for yeast to live on (a 
co-evolution). On an interesting corallary, for matzo to be kosher for 
Pesach/Passover, they have to be baked withing 18 minutes of contact 
with the water. Otherwise, they could be leavened naturally (and 
therefore not kosher for Pesach), which might give you an idea of how 
fast natural fermentation can start.

If the grapes are tart enough, the pH may be too low for the bacteria to 
survive, thus cancelling any need to clean the grapes before crushing. 
For comparison, household wine vinegar is pH 2, along with lemon juice. 
More than orange juice (ph 3), less than stomach acid. The pH of wine 
must (grape juice) is supposed to be around 3-4. From orange juice to 
tomato juice.

On the other hand, yeast is far more tolerant to acid levels and will 
ferment at pH lower than 3.5. I don't know how low yeast can go. Dry 
sherry can start as low as 2.7.

As far as when to pick grapes for verjuis, usually wineries pick and 
crush for wine in October, maybe late September, depending on the local 
climate and that particular season. I would say early August to early 
September. Mostly a guess. You might want to step out once a week to the 
vine and check.

-- 
Edouard, Sire de Bruyerecourt
bruyere at jeffnet.org
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