How to approximate when half the sugar has been fermented

Question

How to approximate when half the sugar has been fermented

lawman

2020年2月18日 19:33

The EC-1118 datasheet suggests a procedure wherein you pitch the full amount of yeast in 10% of the total volume of your liquid, and let it ferment until approximately half the sugar is used up, and then adding this to the rest of your liquid.

While this specific procedure may not be necessary for me, I’m confused on how to do the measurements. How do you calculate when half the sugar has been used up? Measure the brix with a hydrometer and keep remeasuring until it’s half the original brix?

Edit to add: I do understand that calculating the exact amount of residual sugar is much more complex, and is best done with something like clinitest. For this, I don’t think it’s necessary to be extremely precise. I’d just like a method of approximating halfway done.

Topic specific-gravity wine mead yeast cider homebrew

Category Mac

Philippe · Accepted Answer · 2020年2月18日 19:33

Lalvin website recommends to rehydrate the yeast:

Rehydrate Lalvin EC-1118 in 5 times its weight of potable water at 40°C. Let stand for at least 20 minutes then gently stir occasionally to break up any clumps. Add to the must.

https://www.lallemandbrewing.com/en/canada/product-details/lalvin-ec-1118/

What you describe is basically a starter. The difference is that rehydration will only "wake the yeast" and make it ready to start, as opposed to a starter where the yeast is actually starting to multiply and is more vigorous...

In your case, I wouldn't even measure the 50%, I would just wait to see the yeast active (bubbling, foaming) and then add to the must.

Frank van Wensveen · Accepted Answer · 2020年2月18日 10:39

DMTaylor is correct: dry pitching dried yeast almost always works. However, there are situations in which the yeast may rehydrate, come out of hybernation and start the fermentation better if certain procedures are followed. Wine yeast strains are different from beer yeast strains and can be a little more temperamental. If Lallemand suggests such a procedure, my assumption is that they don't do that just to make the use of their products more entertaining. :-) This may be a way to minimize the production of unwanted organoleptics, for example, or to get the yeast to follow a certain preferred metabolic pathway. I'm just guessing here, but my approach would be to follow Lallemand's recommendation for optimum results.

Apart from that, I totally agree with DMTaylor's statements on gravity readings and the fact that you don't need to worry too much about exactly 50% attenuation.

dmtaylor · Accepted Answer · 2020年2月17日 01:08

Refractometers don't measure Brix accurately when alcohol is present. You're better off using a hydrometer if you really want to know when sugar is half gone, then it's just when gravity points are half of what you started with, e.g., when 1.100 becomes 1.050, approximately.

That being said, their procedure isn't critical. Many people would just give it a day or two, then combine with the rest of the batch, and with good success. Personally with dried yeast I don't even go that far. Just sprinkle it into the main batch right away, no "starter" required, and it turns out fine every time. Dried yeast is extremely reliable. If you have concern, you can always use 2 packs instead of 1. Whatever you feel comfortable with.

How to approximate when half the sugar has been fermented

About