Cellar Dweller Getting the best with small batches
Fermentation, filtration and other tips for testing your wine through ‘microvinification.’ By Gary Strachan
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very now and again, you just have to make a small batch of wine. This may be a new grape variety with only one vine, a new treatment you want to try or any other departure from standard protocol in which you don’t want to risk creating a large batch that is a departure from your normal wine style.
One of my biggest small projects was a series of fermentations to test yeast strains. I had accumulated a sampling of commercial yeasts and supplemented the list with another dozen strains ordered from the American Type Culture Collection.I blended some settled white juice from various grape varieties and sulfited to an appropriate level for the pH. The juice wasn’t sterile, but inoculation of clean juice at 300 mg/L of rehydrated yeast should be enough to outgrow a low population of wild yeast.
The tricky part was to find a conveniently sized fermenter. I used 1.5-litre wine bottles with 1.25 L of juice, stoppered with a rubber bung and a fermentation lock. At the end of the fermentation I racked to a 1 L wine bottle and then filtered into a 750 mL bottle.
To sample during fermentation, I removed the bobber from the fermentation lock, inserted a fine tube and drew up a sample with a syringe. I ran the fermentations in triplicate, so I finished the project with three bottles for each yeast strain.
It can be a challenge to find a way to filter small batches of wine. For the very smallest filtrations, a syringe filter can be used. I used to keep a supply of Swinney filters in the lab, but they are pretty small for any volume above 50 mL. A step up from that is to use a MiniJet filter. The MiniJet uses three pads, about 12 cm
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Three-pad MiniJet filter is a step up from using a syringe, but there is some wine loss involved.
square. Accept that you will lose about 250 mL of wine to fill the dead volume of the filter. With a syringe filter you have almost no loss. The MiniJet is also a good lab accessory to use when trying to estimate how much filtration capacity you’ll require for a commercial batch of wine. Choose the same filter porosity as you intend to use and measure the volume to plug 432 square centimetres of filter area. Divide the observed filtration volume
into the volume to be treated and this will indicate how many sq. cm. of filter you need for the batch. It can be a head-scratcher to figure out how to treat a small batch of wine with such things as bentonite or sulfite. Sulfite isn’t a problem because pH sampling doesn’t require that you remove a large volume to test it. Bentonite will require your best guess.
I prefer to add bentonite to white wines immediately after the first
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