Amateur BIAB with some off Flavours

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I'm a part time BIAB with a trusty Big W pot. Each step I've taken from extract, partial, biab, and now kegging with forced carbonation makes a great inprovement in the product.

However from my process I can't seem to shake what I preceive as a slight metallic taste and excess bitterness.

My steps are typical basic BIAB.
1. Mash 64-67 depending typically for 75 mins. Boil for 90 mins with hop additions from 60mins (typically lid on but cracked open to not loose too much to steam). SGs generally right on the money once I top up more water, beersmith uses 65%, but think I'm getting closer to 78%.
2. Cool down by putting it in the laundry trough, cool water fills the trough and hot warmed water exits at the top through the overflow (this is something I need to imrove as depending it can take 90mins to get to pitching temp, though gets down to ~50C reasonably quickly).
3. Pour the whole lot into the fermenter, trub and all (with half batches I can't afford to spare anything), pitch and wait.
4. Depending on the style I; put it in my beer fridge on the vacation setting (maintains 16C), wrap poly pipe around the fermenter with temp probe in fermenter that triggers a bilge pump in an esky that pumps ice water through the poly pipe (the method prior to the fridge), or do nothing (latest strong ale beer, ambient has been 20C inline with the desired fermentation temp). FG is generally where it needs to be +/- a few points
5. Purge keg with CO2, fill it either trough the dip tube or bottling tube to minimise O2 and agitation. Usually theres enough for a 9.5L keg and half a mini keg.
6. Purge the head space a couple of times, in the fridge to carbonate. If dry hopping a hop bomb is added and left at room temp for close to week, then removed, purged again and into the fridge.

The metallic taste slightly noticable, like if you licked a coin or tasted blood (none I can say I do regularly). After the first sips, the pallet adjusts and its not as noticable, but I know its there. All the reading suggests metal contact, which I doubt. The only metal may be from the pot.

The bitterness could just be me needing to adjust the hops, or my pallet, but mine always seem that bit more bitter compared to similar commercial beers.

Any thoughts on what to try to fix this would be appreciated.


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Ok, half of the people here probably know what I'm going to say - so I'll put that at the end...

Most common cause is metal, any brass fittings, especially if they are in contact with the stainless pot?
Metal as salts, how well are your mineral salt additions calculated (if any), are you using 5.2pH stabiliser or similar?
Excess Sulphate can aid in isomerisation of Alpha Acids, but can give a harsh metallic bitterness that tends to linger.
Taste your tap water, Iron from rusting old gal pipes or some brass fittings can throw metallic flavours.
Might be worth doing a brew with store brought water (make sure you add 100ppm or so of Calcium) and see if the metallic flavour persists.

Other causes are a bit more esoteric
Oxidised Lipids, think rancid fat, usually from very old or badly stored malt, massive over sparging. This can be a very complex field, we start getting into things like Auto Oxidation, oxidisation with out oxygen...Take steps to minimise the amount of lipids in the fermenter (as is in keep the ******* hot break out of the fermenter)
Infections, some bacteria can throw metallic flavours. Odds are the beer would get worse with age, if this is the case try a different sanitation regime.
Extreme yeast mismanagement can throw metallic notes, but if its that bad there will be lots of other faults that you aren't reporting.

To try to get rid of the metallic flavour I would -
Look for possible sources of metallic contamination, include above and look for rust or deep scratches in your kettle. When Murrays Brewing moved to their present site, they had to put in a fairly advanced water treatment system, there were a lot of organic iron complexes in the ground water, first trial batches were apparently a bit of a shocker.
Depending on the mash regime, but in the case of an isothermal mash there isn't a lot of point in going much longer than 1 hour, you might be extracting more undesirable fractions from your malt.
Leave the lid off, the highest boiling point liquids that we want to eject are the first to condense on the lid and drip back into the kettle. Boiling covered can do more harm than you think. If you are loosing too much water to evaporation, turn the heat down or top up to target volume/SG with clean (de-chlorinated, just boil the jug and use that) water.
Keep the hot break in the kettle where it belongs, really is important for lots of reasons! one being to reduce the amount of lipids going to the fermenter. I strongly recommend you Google something like "effects of hot break on beer" and read a few of the results.
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