Off Flavours

[Dave.T]

I have been getting off flavours and smells in my brews recently, the only change to my process this year was to fit a 65mm dia flexi stainless tube to the lid of my 100 litre boiler. Before that the boiler would be partly covered with the lid during the boil.
The tube is long enough to bend upwards out of the back of my shed and there is a good flow of steam during the boil, is this enough to drive off D M S or should i look somewhere else for the problem.

[f00b4r]

It could also be condensation running back into the boiler.
I think the easiest way would be to do a boil without the lid and see if you still get the issue, it would tell you if that is the culprit or if you need to look elsewhere.
What are the flavours/smells that you are getting?

[Dave.T]

Thanks for your reply, sulphur comes to mind but something else as well that i can't place. Another thing came to mind since my post, i bought a 500g pack of dried yeast in June last year that has been kept in the freezer, the freezer packed up before Christmas. It was caught quickly, some things had to be binned but i did'nt think any harm had come to the yeast.

[f00b4r]

If you think it’s the yeast you could always buy a 1 or 2 can kit and split it between two fermenters with your test and then kit yeast, it’s a simple and quick test that wouldn’t mean wasting hours on an all grain brew day.

[MashBag]

You don't say what the flavours or smells are?

But.. Is your steam extraction fan assisted and do you have a condensation trap?

[Dave.T]

I can't describe the flavour, a sulphur smell comes to mind and something else that i can not place, i don't have a condensation trap but the flue is angled upwards and then vertical out the back of the shed.
Would any condensation running back into the boiler not be sanitized anyway.

[MashBag]

Dave,

#1Thoughts about your flue
I am not convinced that the condensate is the issue. However boiling off is a purification process and even with modern ingredients it's necessary to get it right.
Chimney's don't work. You need a fan assisted flue. If you have a fan, you must let air 'in'. Steam doesn't move on its own. My "no boilover" lid let's air in the sides. Once the air is moving the stream will condense. It will run back. That's not good.

Simple fix, as soon as the hose leaves the boiler aim it downward before rising up (U bend) and then just make a hole in the lowest point. I use the cheap as chips flexible silver stuff.. Try it.

#2 Sulphur smells (mild rotten eggs?).
I would normally attribute this to lack of yeast nutrition.
Quick fix. Run the same recipe with a new supply of yeast. This shouldn't be a a problem for beer. It is teeming with goodness for the little fellas.

[guypettigrew]

When you say a 'sulphur' smell, do you mean a sharp, nose tingling smell or more of a rotten eggs type smell? If the latter it's probably hydrogen sulphide, which can be produced by some yeasts. Trying a different and fresher yeast would definitely be worth a go.

You say you've stored the yeast in the freezer. Is that as in -18°C? Or is that freezer as in a 'fridge, at +4°C? I'm not sure, but I don't think dried yeast likes to be at -18°C. Freezing and thawing might destroy a high proportion of the yeast cells, leading to off flavours.

Guy

[MashBag]

Good shout Guy. Dried yeast prefer fridge temps.

[john luc]

I believe in having copious amounts of notes for brew day as often weeks later when an issue with a beer pops up I can start with the notes taking on the day. As regards your issue you think it comes from an equipment change. This may be so and DMS and its precursor SMM may be your culprit.
Here is an description,
DMS (dimethyl sulfide)
Flavor & Aroma Indicators: Creamed corn, cabbage, vegetal, and stewed tomato in darker beers.
How it Happens: DMS develops at high temperatures (above 140°F) and is expelled easily while the wort (the beer before yeast is pitched) still boils. The precursor to the off-flavor is s-menthyl methionine (SMM), and comes from the grain during the boil.

“It presents as a sulfery-corn or ketchup aroma and is common in beers that utilize raw grains or lighter roast malts like pilsners and saisons,” says Rick Dankert, brewer at Georgetown Brewing in Seattle, Washington. “The best advice I can give is to use the freshest grain possible. If it’s a year old, throw it out. And make sure you get a vigorous boil for at least fifteen minutes”

[Dave.T]

Thanks for all of your reply's , i did a smaller brew yesterday with the lid completely off and see how it goes. The grain is fresh and i crush it myself.
In the past i have boiled with the lid partly on and not had any problems, it seems to be since i fitted the flu that the problems started.
At 65mm inside dia i thought that would be enough volume to drive off enough steam, seems not!.
Thanks again for all of your advice.

[MashBag]

If you go to 100mm that's a more usual size.
Duct, pipework, fans etc cheap as chips and will whistle the steam away.

[Dave.T]

Just a quick update on the brew, it's still got maturing to do but looking very good, No off flavours or smells, thanks again for the comments and advice.

Dave