Sodium hydroxide as pH adjuster for rum wash?

Discuss safety issues here.

Sodium hydroxide as pH adjuster for rum wash?

Postby RumFiend » Tue Dec 23, 2014 6:11 pm

Scenario: a 4th gen rum wash didn't take off when yeast was pitched so 4 tablespoons of NaOH (sodium hydroxide) were added to bring the pH to 5.10. This pH level was chosen based off the result of a similar batch (3rd gen wash of same dunder lineage) whose pH needed adjusting (up to 5.48) to get the fermentation to take off.

There was a considerable amount of dunder used for this wash, 50% in fact, which is a bit more than the usual.
I couldn't find much on sodium toxicity except for this article on google scholar, http://mmbr.asm.org/content/74/1/95.full, which I couldn't really extract any meaningful information from. There was one thread here which concerned NaOH and listed ppm values but nothing as the details of the toxicity (are toxic byproduct pathogenic to humans produced? is the toxicity to do with the yeast?).

After the pH was adjusted, stirred thoroughly, and left to sit for 3 hours the yeast appeared to spring back into action, creating swirls of activity on the top of the wash. However an unusual smell was noted, slightly 'fishy' and/or pungent, much more so than a Pugirum wash usually would.

I'm going to monitor the wash over the coming days but I was wondering if anyone could provide some safety info regarding sodium hydroxide in washes. Does it suffer a similar ammonia-producing problem that sodium carbonate during distillation of low-wines does?

If NaOH proves troublesome I'm either going to have to use less dunder in each new wash (not ideal as I want to build up flavour quickly), or find a better pH adjustment compound (and it looks like sodium (bi)carbonate is outa the picture as a inconveniently large amount would be needed). I wonder how the commercial distilleries deal with this problem?
If NaOH proves troublesome I'm going to have to either use much less dunder so as not to effect
RumFiend
 
Posts: 71
Joined: Wed Jan 09, 2013 12:31 am
equipment: idea reflux.
common-sense condenser.

SS plated bubbler

Re: Sodium hydroxide as pH adjuster for rum wash?

Postby Meatheadinc » Tue Dec 23, 2014 9:01 pm

Although I have no personal experience with lye- caustic soda. I have heard of its use in distillation.

It has been long time since chemistry class but I believe it will make a great buffer ( sodium citrate) when combined with citric acid, similar to sodium carbonate and citric acid but will require less volume.
Meatheadinc
 
Posts: 561
Joined: Thu Aug 29, 2013 9:00 pm
Location: Far North Coast NSW
equipment: 2" LM/VM on 30L boiler
4" FSD Neutraliser 50L boiler
4" carter head thump column
"Control Freak"- Semi Automation

Re: Sodium hydroxide as pH adjuster for rum wash?

Postby wynnum1 » Tue Dec 23, 2014 9:20 pm

POTASSIUM BICARBONATE they use for wine but wine may have different acid to rum.
wynnum1
 
Posts: 1494
Joined: Tue Jul 26, 2011 1:18 pm

Re: Sodium hydroxide as pH adjuster for rum wash?

Postby db1979 » Wed Dec 24, 2014 12:20 am

I suspect your problem with the fishy odour is more to do with your dunder or the amount of dunder. Sodium hydroxide will not have any impact on anything other than adjusting pH, unless it isn't stirred in well (at high concentrations it could cause unwanted degradation of esters and other chemicals that you may want to keep in your ferment, but stirring during the addition should prevent that and it would only be minimal and affect only a very small portion of your wash).

It will react with acids to neutralise them and the result will be the sodium salt of the acid and water. The sodium salt of any acid that you currently have in your dunder will not be any more toxic than the acid itself so there shouldn't be any concerns there.

Now the fishy smell is most likely due to an amine that WAS protonated (in its acid form, and far less volatile, or smelly) or acidified prior to the addition of the sodium hydroxide whereupon it then became the free amine (after reacting with the sodium hydroxide) which is much more volatile and hence the smell.

So I think you've already answered your own question... use less dunder if you want to minimise the smell.

Also potassium bicarb and sodium bicarb will have the same result... the smell is not caused by the base that you use, rather that the pH has been adjusted to a point where the smelly chemicals are now volatile.

As meatheadinc said, sodium hydroxide when used with citric acid will buffer your wash.

Hope this makes sense, I've had some beers...
db1979
 
Posts: 1760
Joined: Sat Dec 29, 2012 3:47 pm
Location: South of the big smoke in banana bender land.
equipment: Eve - 4" x 4 plate solid state bubbler (sieve plates), 330 mm packed section on a keg boiler with 2 x 2000 W elements.
Currently having a makeover: 2" x 4 plate solid state bubbler (1" bubble caps, no sight glasses...maybe not for much longer!) on a bain-marie boiler.

Re: Sodium hydroxide as pH adjuster for rum wash?

Postby db1979 » Wed Dec 24, 2014 12:28 am

The article you linked to basically says that yeasts are known to have ways of dealing with high concentrations of sodium and potassium ions and it was summarising the research that has taken place to work out how yeasts do this.
db1979
 
Posts: 1760
Joined: Sat Dec 29, 2012 3:47 pm
Location: South of the big smoke in banana bender land.
equipment: Eve - 4" x 4 plate solid state bubbler (sieve plates), 330 mm packed section on a keg boiler with 2 x 2000 W elements.
Currently having a makeover: 2" x 4 plate solid state bubbler (1" bubble caps, no sight glasses...maybe not for much longer!) on a bain-marie boiler.

Re: Sodium hydroxide as pH adjuster for rum wash?

Postby RumFiend » Tue Jan 13, 2015 12:51 am

db1979, fantastic reply, thorough and thought out, and definitely made sense. Cheers mate 8-)
RumFiend
 
Posts: 71
Joined: Wed Jan 09, 2013 12:31 am
equipment: idea reflux.
common-sense condenser.

SS plated bubbler

Re: Sodium hydroxide as pH adjuster for rum wash?

Postby RumFiend » Fri Jan 16, 2015 5:49 pm

RumFiend
 
Posts: 71
Joined: Wed Jan 09, 2013 12:31 am
equipment: idea reflux.
common-sense condenser.

SS plated bubbler


Return to Safety Discussion



Who is online

Users browsing this forum: No registered users and 12 guests

x