Too much copper?

[Detritus]

Hi,

I made a WN1 variant recently, I couldn't any WGJ so I used a couple of small cheap Munton's kits.

I thought I'd be clever and introduce the nutrient in three batches, theoretically to prevent the yeast thinking they had a vast supply of nutrient and then finding at their peak that there was now none left and making life stressful for a larger population than they would otherwise have bred to.

This was either a bad strategy or, more likely I executed it badly, and it created the biggest bad egg smell I've ever concocted. Maybe I should have let it fix itself, but while reading on the internet about mercaptans and disulphides I talked myself into introducing copper.

I used a stack of copper scrubbing sponges in a 2L drinks bottle with the bottom cut off. I rinsed this with gallons of water, but I noticed when draining it that a few drops of surprisingly coppery water came out.

I siphoned the 5 gallons through it. It totally killed the smell.

I'm wondering now though how much copper I've really added to this wine. I've tried a small sample and didn't detect a metallic taste, but I don't trust that much as I've a chequered history of chilli abuse.

What do you reckon? Chuck it to be on the safe side, test it some how (cheaply?), or assume it can only have been a few mg's?

Regs, Tom.

[Cellar_Rat]

This is something I have thought about but never actioned.

Copper is avoided in general winemaking. With this one exception -to remove hydrogen sulphide (rotten egg smell) if the fermentation has proceeded with two little nutrient.

Contact with copper (stirring with a rod) or the addition of copper sulphate can be used in these circumstances.

Racking over copper scrubbers was something I had considered, if I ever had the problem because it would increase the surface area contact, but reduce the risks associated with adding copper sulphate.

I think it sounds like it has worked - you are certainly more bold than I - I would have perhaps started with just the one scrubber

Do not give up hope, I would bed the wine down for bulk storage now adding metabisulphite normally.

BUT please remember excessive amounts of copper can be harmful. The next stage is testing it (before drinking it)

SO.....

What we really need now..... is a chemist to pop along and tell us how to conduct a copper test - I see some ammonium hydroxide and a titration coming on !!

[SiSandrine]

I have had this problem occasionally, it is usually caused by as Brian says stressed yeast due to too little nutrient or reduction caused by leaving on the lees too long (this is where it usually gets really pongy).

Whenever I do this I favour adding copper sulphate solution as you can be reasonablly sure exactly how much you add. I also then fine the wine with bentonite and leave for a few months. Rack carefully and then filter/bottle etc in the normal way.
With the copper rod or scrubbing brush this is much less certain and whilst it may not seem a lot you just can't be sure. Whilst it doesn't sound like you added a lot here, if you are concerned then unless you really can get a chemist (there are a few around here somewhere) to help you work out exactly how much copper is in there then you could put it down to experience and start up a new batch.

Hope this helps.

[Cellar_Rat]

Don't bin this yet. There are as Simon says some pipette jugglers on there. Stablise and store. Labs will test for you for c.£20

Simon - What maths do you use for adding copper sulphate ?

[NorthernWiner]

I have had this problem occasionally, it is usually caused by as Brian says stressed yeast due to too little nutrient or reduction caused by leaving on the lees too long (this is where it usually gets really pongy).

Whenever I do this I favour adding copper sulphate solution as you can be reasonablly sure exactly how much you add. I also then fine the wine with bentonite and leave for a few months. Rack carefully and then filter/bottle etc in the normal way.
With the copper rod or scrubbing brush this is much less certain and whilst it may not seem a lot you just can't be sure. Whilst it doesn't sound like you added a lot here, if you are concerned then unless you really can get a chemist (there are a few around here somewhere) to help you work out exactly how much copper is in there then you could put it down to experience and start up a new batch.

Hope this helps.

Simon has the absolute correct approach. This is exactly what I do as well. Using Copper Sulphate solution is the most effective (and measurable) method for removing H2S. Bentonite is then added to fine out the residual copper.


Not surprisingly, this is also the method used by commercial wineries (and anyone who tells you the big wine producers don't have these same problems is spinning a yarn).

[NorthernWiner]

Here is a great article on treating hydrogen sulphide issues;

http://www.bcawa.ca/winemaking/h2s.htm

[Cellar_Rat]

Steve - Would fining with Bentonite work for Tom? How do you know that all the residual copper is fined out ?

[NorthernWiner]

I'm fairly certain it would. Using copper scrubbies, there's no way of knowing how much copper ended up in the wine. But in my country winemakers are allowed to add up to 10 times the legal limit for removing H2S, provided it meets federal safety standards after fining. From what I've read, bentonite is so effective at removing it, that it's rarely a problem.

Of course the only way to know for certain if it's safe is to send a sample off to a lab for analysis.

[Detritus]

Thankyou everybody for your comments, most insightful.

I have some copper sulphate but I figured I could make an order of magnitude error with that quite easily and would be safer with copper solid; I had no idea that copper (not even a compound of it) would leach so easily from the sponges. I shall use sulphate next time, sanity check my sums against that link you provided Steve, and maybe post my sums to be on the safe side!

It's been in bulk for a month so I'll whizz up some bentonite and add it this weekend and leave it a few more.

I thought bentonite left for a few months would impart an earthy taste? Lesser of two evils either way, especially if bentonite is that great at removing copper.

A couple more questions if I may:

Any hobbyist-approachable UK labs you guys have used that I should be aware of?

I have a vinbrite mk3 and some medium filters. Should I use a 'fine' filter instead do you think? I haven't used it yet and no idea which of the two meshes to use when.

Cheers, Tom.

[SiSandrine]

Don't bin this yet. There are as Simon says some pipette jugglers on there. Stablise and store. Labs will test for you for c.£20

Simon - What maths do you use for adding copper sulphate ?

The article that Steve sent was the one I use. I am fairly sure that Steve pointed me to it previously. I bought the ascorbic acid from Holland & Barrett and the copper sulphate on line. I have a life times supply of both.

[Detritus]

I've just filtered the coppery wine to which, at your suggestions, I added 5tsp bentonite a few months ago.

I couldn't believe how much fluffy sediment appeared to collect at the bottom of a previously fined and cleared wine, I couldn't see any of the bentonite at all just half an inch of extra sediment. Very surprising.

I'm not sure the (Vinbrite) filtering did much - viewed at right angles I could just about see the passage of a torch beam through it both before and after, but the filter did have a small amount of muck on it afterward.

Thanks all, I'm very glad to not pour this one away, it's the first and only wine I've added elderflowers to and the pepperyness and bouquet is great; might add a bit less next time