My second brew was today and I have a sample from before the wart was throw in the fermentation bucket. It's a rye IPA and the sample tastes very bitter. I know that's to be expected, but I feel like it's more bitter than I thought and I am paranoid that the whole grain steeping might have released tannins. This is because we let the temp get slightly above 170 for a brief period (maybe 2 minutes - my girlfriend turned the burners up when I wasn't looking). I guess there's no way to know by asking on here. I guess my question in general is: does the wort(?) taste extremely bitter before fermentation vs. after? Would you be able to definitely taste tannins vs. hop bitterness? (Hops used were Magnum at boil followed by Omega at 35 minutes.)
To answer this specific question:
'does the wort(?) taste extremely bitter before fermentation vs. after?'
Typically yes. Bitterness from hops is in the form of hydrophobic (water-repelling) iso-alpha acids. During fermentation these will tend to associate with:
- Yeast cells (taste some yeast slurry and you're sure to notice how bitter it is)
- Fermenter walls
- Rising bubbles of CO2
- Pretty much any surface
and be lost from the finished beer. So, when we use hop utilization values during the boil and whirlpool (roughly up to 35%) these actually take into account how much bitterness will likely be lost during fermentation (i.e. it represents the overall efficiency, from wort to finished beer, not just the efficiency of kettle utilization).
This is also why it's good to use standard utilization values as a starting point for your own setup, not an absolute standard; your fermentation procedures may well cause you to lose noticeably more/less bitterness than the next brewer.
Tannins will be apparent as an astringent dry bitter mouthfell that doesn't fade on quickly at all.
It doesn't take much time to extract tannins. But requires temp 170°F or above AND a pH of 6.0 or more.
Of this temp slip happened late in the mash its very likely that your pH was below 6.0 and there's no risk of tannins.
One tell tell sign is that your pre hopped wort will be astringent right out of the mash.
An inexperienced palet may not be able tell the difference from hop bitter and tannin astringentcy. But they are very different, mainly tannins will feel like a dry wine mouth feel rather than a bitter flavor.