SG for newbies

[Scientific hippie]

OK, I am confused again, despite having acquired some books.

I siphoned my elderberry wine from concentrate at an SG of 0.990 the the other day according to the recipe; because I didn't realize that fermentation had stopped naturally, I added a packet of Montrachet, which quickly fell to the bottom. Today I decided to rack it again; I didn't feel like bothering with the siphon and tubing for one gallon, so I filtered it into a clean jug using a coffee filter. It took a long time, but it looks and smells very good. It tastes like a wine under construction; a somewhat harsh but nice nose, definite fruit flavor, and a short, bitter finish that I guess is from the tannin.

As I mentioned, I am making elderberry wine from several different recipes that call for concentrate (one recipe) or dried berries (two recipes, one with raisins and one without), in anticipation of my own elderberry harvest next year. The other two recipes call for beginning secondary fermentation when SG reaches either 1.010 (no raisins) or 1.030 (with raisins). I measured an SG of 0.992-0.995 among the four buckets (two with raisins and Montrachet or Lalvin 1122, two without raisins and the same two yeasts). The books don't clearly state that SG goes up or down with alcohol concentration. These all smell strongly of alcohol; there is an occasional bubble in each of the airlocks. Did I ferment them for too long? Do I need to add sugar and then secondarily ferment? I see some recommendations that one measure the starting SG; I didn't do that (I will next time; live and learn).

 

[bernardsmith]

My preferred approach - and others will have different protocols - is to rack from my primary bucket when the gravity drops to around 1.005. The fermentation is still active and the yeast is still pumping out CO2 but much of the yeast is likely to have dropped towards the bottom of the fermenter. If you rack earlier and you don't "degas" (ie stir regularly to remove CO2) then you can rack the mead or wine off too much of the yeast (you will leave behind all the sediment and that sediment is full of viable yeast cells) and so the fermentation CAN stall. Others suggest that you rack when the gravity drops to 1.010...

But the point when you rack should have nothing to do with the recipe and whether there are raisins in the mead or wine. In fact many older recipes suggest the addition of raisins AS IF raisins are a source of nutrients. They aren't. Sure grape wine may not need added nutrients but then you are using bushels of grapes (the unoxidized fresh "raisins") and not a handful of dried grapes.

How much sugar fresh elderberries (or dried) may have in them I don't know. You might check out what the sugar content of elderberries are. I think they may have something like 7 g of sugar /100 g of fruit. (450 grams of sugar (about 1lb) mixed with water to make 1 gallon will raise the gravity of that gallon by about 40 points (1.040). If you know how much sugar you added to your must, you know how much fruit was in the must and you know the total volume of the must then you can calculate the starting gravity. (and if you know the finishing gravity then you can calculate the alcohol by volume (ABV) of your wine).

 

[Scientific hippie]

So if my SG is < 1.005, I should rack? I added 2 lb. sugar to the raisin-less 1 gallon batches and 2.25 lb. to the batches with raisins. Do I need to get the SG up to the recommended 1.010 and 1.030, respectively, and then rack? I can't find anything on the sugar content of dried elderberries.

 

[bernardsmith]

Not sure I completely understand. When we ferment sugars we are typically looking only to ensure that the gravity continuously drops from the starting gravity to the gravity we aim for to bottle - A continuous downward trend. There are two exceptions.
1. When that final gravity is reached and you want to "back sweeten" the wine or mead. You then stabilize the wine and add more sugar. That added sugar increases the density so in fact you have increased the specific gravity. But in this case you are not fermenting the added sugar. You want that sugar to remain unfermented which is why you have stabilized the wine (preventing any remaining yeast cells from fermenting the sugar).
2. The other exception is when you step feed the yeast more sugar as the fermentation continues and the gravity drops towards 1.000. You step feed if you want to make a sweeter mead or wine but you don't want to back sweeten. In that case the technique you use is to provide the yeast with more sugar to make more alcohol than the yeast itself can tolerate. It then quits fermenting leaving some sugar unfermented. The problem here is that that amount of sugar in concentration at day 1 may be too much for the yeast to transport the sugar molecules through the cell walls of the yeast and so no fermentation may occur: think undiluted honey as an extreme example. Step feeding provides the yeast with concentrations of sugar it can handle.
All that said, I am not sure if your last post suggests that you now want to add more sugar to raise the gravity so that it is "high enough" for you to rack. If the gravity has dropped to about 1.000 then the only thing you want to do is rack right away to inhibit oxidation. Adding MORE sugar is contra-indicated IF you started off with the amount of sugar you needed to create the wine you want.

 

[Scientific hippie]

Thanks, Bernard! I think I get it now.

 

[Scientific hippie]

I just racked everything; one bucket spilled; I cleaned it up. Glad I still have four more gallons to experiment with.

 

[bernardsmith]

Herding carboys is just as hard as herding cats.

 

[Scientific hippie]

Yeah, especially the plastic buckets that tip over easily! I ought to change my personal photo to a photo of my latest spill! I've had two with the elderberry juice. I also had to make an emergency elderberry run and had to improvise a closure for my first batch of graf with the original apple juice bottle cap that my husband drilled and lined with a rubber grommet ("Oh, you wanted a grommet! I don't know why you kept asking for an O-ring; that wouldn't work!") Drill presses: the gift that keeps on giving.

 

[bernardsmith]

But buckets should be designed to have a low center of gravity. Tipping over a bucket should be a real challenge - TRIPPING over a bucket, on the other hand,
can be a problem if you use the floor as your fermenting surface.

 

[Scientific hippie]

I think I had a lot of the must siphoned out. I was standing at an awkward angle (I have four gallon jugs on a low shelf) and I must have been pumping the siphon in a way that pulled on the tube and that pulled the bucket over.