View Full Version : PH and sulphur smell

03-12-2013, 10:18 PM
So, I have two traditionals and two hydromels on the go. Recipes as follows:

3lb / 1.5lb honey (trad/hydro)
Water to 1gal
yeast: 71B

- Prepared musts, added campden tablet to each, waited 24hrs.
- Pitched yeast. Added 1tsp nutrient (tronozymol) to each after lag.
- 24hrs later, aerated and took SG and pH readings

At this point I went out for 6hrs. On my return, was met by an eggy sulphur smell. Took some new pH readings. Changes from 6hrs previous were as follows:

Trad 1: 3.8 -> 3.1
Trad 2: 4.3 -> 3.0 (worst smelling)
Hydro 1: 3.8 -> 3.0
Hydro 2: 4.0 -> 3.4 (least smell)

So I reckon the smell was due to the high acidity. Have added 1tsp of calcium carbonate to the first three, .5tsp to the last to raise the pH. Also gave the traditionals their next lot of nutrients. Hopefully that'll work.

Now these drops in the pH seem quite large to me, given the time period. Any idea what might be the cause, and how can it be avoided in the future?

03-13-2013, 12:36 AM
No probably wrong correlation........

The sulphur smell is caused by stressed yeast. Generally by yeast that are under nourished.

The cure is usually to give it a damn good stirring to and then more nutrients.

03-13-2013, 03:23 AM
I've found 71B can be a pain, although I still like the results.
Got one in secondary that had a very similar problem, partly nutrient and partly pH related.
Fatbloke is right about the yeast being stressed though. If the pH had got much lower then it would become a real problem, but a big contribution to the smell would be that they were just hungry little buggers.
Keep an eye on the pH as you go and be sure to aerate lots and feed as necessary.

A Stephenson
03-13-2013, 04:02 AM
Hi SilentJimbo,

What temperature was the must?

Next batch of mead try and use potassium carbonate to raise the PH prior to pitching the yeast, mine dropped by 2.9.
Had the same problem with 71B, my starting PH was 6.5 and after about 48 hours the 10g of 71B were going strong, I had plenty of nutrient with 840g of pollen plus half nutrient addition, PH dropped to 3.6 and started to get a light rotten egg smell, however the must did reach a temp of 24.5c

I pitched 1L of water with 14g of calcium carbonate, 4 tsp of Tronozymol and raised PH to 4.1, dropped temp to 18-20c and aerated must. Smell dissipated. My OG was dropped from 1120 to 1000, which is around 16%.
The yeast were so happy that I cold crashed at 1004 to try and prevent must becoming too dry. Checked the PH and it dropped from 4.1 to 3.9.

In my case I think temp was too high and caused them to become smelly. As the final PH drop was 2, had I not increased PH it may have ended up at 3.4

Starting a new batch of traditional mead today with 71B and will post results under the Lalvin 71B experiment under the mead log. Hopefully the starting PH will be around 6.5 and I will keep the temperature under 20c and add only 5g of 71B for 27 liters, as 10g dried out my must and I want to keep residual sugars.

The recipe for my last batch is below.

Sweet Sack Traditional Mead

25 Litre Batch (Adjusted to 28L due OG)
Abv 14 - 15%
OG 1135
FG 1025
PH 3.7 - 4.6 Fermentation Range.
Starting PH 6.5
At Racking PH 3.9
Desired PH 3.3

Honey Tesco Honey EU & Non EU Blend - 26 x 454g Jars @ 11.80kg
Values Per 100g; Protein 0.5g, Sugar 81g / Tablespoon Sugar 12.2g, weight of honey 15g.
(454g Jar = 367.74g Sugar content x 26 = 9.561Kg)

Spring water 20 L (10 L Chilled)
Pollen 30g/L = 840g
Tronozymol (Yeast Nutrient & Energiser) @ 28L 3tsp/4.5L = 18.5 tsp.
Staggered Additions 18/4 = 4.5tsp per addition
Yeast Lalvin 71B-1122 10g

03-13-2013, 07:26 AM
This morning the sulphur smell had been replaced with more of an apple smell, so I guess my additions did the trick. Will have to keep a close eye on things though.

BTW, how much Tronozymol do people recommend using? I had reckoned on about 9g/2tsp per gallon, with half of that at the end of lag, but it seems this might not have been enough.

Must temperatures are at about 21C, so shouldn't be a problem.

And Stephenson, my understanding is that amount of yeast added won't make a difference to the final gravity, as they multiple to the same amount anyway.

A Stephenson
03-13-2013, 09:08 AM
I follow the instruction on the back. Medium to Sweet mead 3tsp/4.5L
for my 28L batch I would use 18.5 tsp.

I would add 5 tsp to the must before pitching.

4.5 tsp 24 hours after fermentation starts
4.5 tsp 48 hours after
4.5 tsp 72 hours after

Dry mead would only require 2tsp/4.5L

You could also add a cup of pollen, can buy it from Ebay and this has really kept my yeast happy.

Using too much yeast is said to impart more esters, off aromas etc.
If 5g will act on 23L then nearly 6g will ferment 27-28L

I will use less yeast have decided to make a mead using Lalvin D47 6g for 27-28L and I am testing another 4L batch with pollen and the remaining 4g of Lalvin D47.

Good to know what PH level 71B starts kicking off smells.


03-13-2013, 04:49 PM
Tronozymol isn't too common in the US, so there probably isn't a lot of info here. Looks like the UK folks will be your source on that.

Sharp pH drops in the first day, or even few hours, of fermentation are common. During the lag phase, the yeast are acclimating to the environment, and also changing it to their liking. Organic acids are produced to drop the pH and discourage the growth of competing organisms. Obviously this is #1 on the list of things for the yeast to do (defend your territory!). So usually the pH drops a lot on the first day, and then stabilizes or drops only a little more.

A pH of 3.4 is usually ok, although the yeast can still be stinky if underfed. Some strains are fine down to 3.2, and I've had a few fermentations go swimmingly at 2.8 (and that's low!). Proper nutrition will help the yeast defend against the low pH, so it's kind of a runaway feedback loop and best to catch it early.

If you have some DAP, FermaidK, Wyeast "yeast nutrient", or stuff like that, you might consider adding about 1/2-1 tsp per gallon (3.8 L) per batch, except for DAP which you only need about 1/4 tsp to start off (I think, I work in grams usually so you're best to double check the tsp numbers). Tronozymol? Go with A Stephenson's directions and see how that goes. The calcium carbonate also dissolves slowly, so be sure to wait a little while before deciding to add more. Having to correct your corrections is annoying.

03-13-2013, 06:27 PM
Thanks for the help. I think I panicked a bit from the smell and the sudden drop in pH, but it seems to be going smoothly again now.

So if the yeast want the lower pH, is it best to treat such problems first with extra nutrients, only using the calcium carbonate if things get critical, rather than trying to fight the yeast over the acidity. Also, what's the downside to raising the pH by too much?

I thought I'd take the opportunity to ask about Tronozymol having noticed that all the other replies were from UK people. Seem to only be able to get Trono and DAP over here...

03-13-2013, 07:08 PM
pH drops are ok...as long as it doesn't drop too far. Traditional meads (just honey, water, nutrients, yeast) are the most prone to rapid drops in pH, as they are the least buffered. Adding fruit, grains, etc tends to moderate the pH drop. Many people will add some bases (e.g. potassium carbonate) up front to traditional mead musts to add some buffering capability. Other times you just see how it goes, and add if necessary. Depends a bit on your source water too, as soft water typically has less buffering capability, although the difference is likely small unless you've got seriously hard water.

Nutrient additions will help the yeast out in lots of ways, and many will also buffer the mead as a side-effect. It's not a cure for the pH being too low, but well-fed yeast will be able to handle lower pH before it gets to be "too low".

Besides allowing for the growth of other organisms (most will kick out when the pH gets below 4.0), too high a pH tends to make your mead taste flabby. Acidity gives it a bit of a punch, and will counterbalance residual sweetness and the inherent sweetness of alcohol. This is why you will see some folks add acid blend as a flavor adjuster. Old recipes call for acid up front, but that is a holdover from fruit wine making, where you need to add acids to mimic grape must. Honey has its own acidity (as you've seen), so up-front acid additions are unnecessary.

A few ingredients tend to lower the pH, e.g. lemon juice, so when using a lot of those you might want to adjust the starting pH into the 4-ish range. Mead musts as-mixed seem to range anywhere from the high 3s to around 7 (neutral), but all typically wind up between 3.0 and 4.0. 3.4-3.8 is usually considered the "sweet spot".

03-14-2013, 08:23 AM
Random question: If someone was to, say, stick their nose into a demijohn full of H2S producing mead, could it cause a mild sunburn-like effect?

03-14-2013, 09:43 AM
Random question: If someone was to, say, stick their nose into a demijohn full of H2S producing mead, could it cause a mild sunburn-like effect?

Is that someone you Jimbo or a 'friend'? ;) Honestly i don't know

03-14-2013, 11:23 AM
The CO2 coming off a fermentation can make you light-headed (or flat-out kill you!). I can't imagine H2S would help with that sensation.

03-14-2013, 12:16 PM
It's more that the skin on my nose went a bit red and flaky shortly after doing so.
Could just be a coincidence - guess I'll find out the next time such a smell develops...

Marshmallow Blue
03-14-2013, 12:20 PM
The CO2 coming off a fermentation can make you light-headed (or flat-out kill you!). I can't imagine H2S would help with that sensation.

Sounds like a Darwin Award. I think it would be difficult to accidentally self terminate by sniffing CO2 from a Carboy / Demijohn, as there is plenty more air around the container. So when you started to feel the sleepy effects, you would put the carboy down, then be exposed to fresh air again. Even if you got to the point where you passed out I think you would be able to recover from air moving back through your system. I don't know, I'm not a scientist.

03-14-2013, 12:29 PM
When setting up my meadery (in a large cupboard in my bedroom), I calculated that (I think it was) 20 gallons of fermenting mead would produce CO2 at (very) approximately the same rate as a person does, so I don't think there's much risk of fatality...

03-14-2013, 02:06 PM
Small homebrew sized fermenters won't kick out enough CO2 to kill you, but you do occasionally hear of a production brewery where someone gets knocked out by a large (many barrels) container. Fatalities have occurred. :(

Marshmallow Blue
03-14-2013, 03:05 PM
It's sad. The real solution to this problem is obviously growing a tree inside the brewery, or your house.

Chevette Girl
03-17-2013, 12:46 PM
Or the waft test from chemistry lab... keeping your nose well away from the source of the odour, you gently waft it towards yourself with your hand, getting closer until you can just smell it (that said, even having taken a number of university level lab courses where this is standard procedure, I've still knocked myself on my butt more than once forgetting safe procedures and sniffing deeply of my musts, <snifffff> "Whoooo, I must sit down now!" <thump>).

And while it certainly is possible to give yourself a chemical burn, I don't think there could be enough to burn the outside of your nose without making the inside of your nose pretty tender too, if you were actually inhaling.

At least I've learned how to only inhale enough air to smell and not get it all the way into the lungs when I check my sulphite solution, if I take a good sniff near that stuff, I'm out coughing for a while, it irritates the hell out of my lungs.

And spiderplants. They are great for soaking up CO2 and don't need a lot of light so they're perfect for a brewing area!