July 04, 2019
When We Last Left the Barkshack Gingermead it was fermenting strongly, fizzing away for five days. When the vigorous fermentation dropped off, we took a specific gravity reading.
The reading went from 1.044 to 0.994, indicating complete dryness and an alcohol by volume of around 6.5%. That was a little more than expected: the Saison yeast is very thorough!
The colour is great, and the aroma is fantastic, but the flavour is dry. It isn’t overly acidic, and the tannins derived from the raspberry seeds aren’t overwhelming (on the contrary, they're like a backbone running through the mead) but it needs some sweetness to bring out the character of the fruit. Interestingly, it has a light but definite honey aroma and flavour. It's great that it carried over the fruit, ginger and lemon notes as it really adds to the character of the mead.
To get it into shape for carbonating and drinking, we're going with a standard winemaking processing addition for fruit wine: sorbate, sulphite, and finings, followed by an adjustment for flavour. The three need to be done to any wine that’s going to be back-sweetened and not Pasteurized or sterile-filtered.
Sulphite stuns yeast and forces some cells to dormancy while preventing oxidative damage. Without sulpite additions the mead would lose that gorgeous colour and start losing flavour pretty rapidly, especially after getting exposed to oxygen. The measured pH is 3.2, and a single dose to bring it up to 50 PPM FSO2 will allow for some to be burned off in processing and absorbed by oxygen extant in the mead already.
If you have questions about sulphite, we'll be addressing it in a future blog. Short answer, it's a wonderful, magical additive that makes life better for everyone, nobody is allergic to, and everyone should use it all the time.
The finings act to remove colloids, proteins and other material from solution, making it clear, but more importantly from a stability standpoint, they remove yeast cells, and that’s part of the strategy to get the mead stable enough to bottle. A good fining regime can reduce the yeast population to the point where they will no longer make alcohol and carbon dioxide, even if there is enough nutrients and food for them to do so.
This is because yeast has two different schemes that are in operation in an alcohol fermentation. First, they breed up to culture strength, which is on the order of 10 to 20 million live yeast cells per millilitre of wine (or beer or whatever). When they hit that mark the population levels are too high, so they stop breeding. It happens all at once, and while it’s got to be some kind of chemical signal that does it, nobody has caught them at it yet.
After they stop breeding, they change their metabolic pathways and start turning sugars and nutrients into carbon dioxide and alcohol, rather than into millions more daughters. They’re ruthless, but practical. When they run out of food, they mostly go dormant, and a good percentage of them die. Between the sulphite stunning them and the finings pancaking most of them down to the bottom, they cease most activity.
The next stage, adding back sugar to balance the flavour of the mead, will cause any yeast cells present will start breeding again, and when they hit that magic 10-20 million mark, the wine will go cloudy and re-ferment. And that’s where sorbate comes in.
Sorbate is a polysaturated fat in the form of sorbic acid. It’s found in blueberries, huckleberries and mountain ash berries in large amounts. It’s a food additive recognized by Health and Welfare Canada, and it’s classified as GRAS (Generally Recognized As Safe) meaning it’s pretty darn benign. One of the more thorough studies I’ve read showed that the only side-effect to large-dose feeding of sorbate to rats was a slight extension in life span (attributed to a protection against lung infections engendered by the sorbate).
Here’s the fun thing about sorbate: it doesn’t kill yeast. It doesn’t even make it late for work. What it does, is prevent yeast cells from budding off new daughters. It’s birth-control for yeast. That’s why it’s so useful. When you get the yeast population below the fermentation level, then add sorbate, the yeast can’t climb back up to the point where they can start making carbon dioxide and alcohol, and they leave the sugar and nutrients alone, so the wine doesn’t change character or flavour/aroma.
After the sulphite, the mead gets 250 PPM of Sorbate and a dose of gelatine finings. Gelatine is a potent fining agent, and it reacts strongly with tannins, working to tame some of the raspberry seed tannins.
After filtering we get a beautiful, sparkling clarity, but more importantly we reduce the yeast cell populations to a very low level, ensuring that with proper care it won't re-ferment.
The mead is still very tart and crisp, so to make it lively, crisp and luscious we'll need to sweeten it.
A kilogram of sugar heated in 500 ml of water, along with a pinch of citric acid, makes invert syrup. The advantage of invert is that it not only dissolves easily, but also it won't re-crystallize over time. Adding to taste, about 2/3 of it went into a 19 litre Corny keg and was gently stirred to mix.
Frothy shiny goodness
Chilled and carbonated, it's time to taste! The glass looks cloudy, but that’s condensate: the mead is perfectly clear, and it's fresh, crisp, lightly but positively gingery and redolent of raspberry, lemon and honey.
Success! So popular we have to make another batch right away--but that's pretty easy.
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January 31, 2020
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