Temp hit 170 for a short time?

Tannins And Astringency

If you are worried about squeezing your bag too much or crushing too fine, relax! Astringent beers do not come from finely crushed or squeezed husks but come rather from a combination of high temperatures and high pH. These conditions pull the polyhenols out of the husk. The higher your pH and the higher temperature you expose your grain to, the worse the problem becomes. Any brewer, traditional or BIAB, should never let these conditions arrive. If you do allow these conditions to arrive, then you will find yourself in exactly the same position as a traditional brewer. Many commercial breweries actually hammer mill their grain to powder for use in mash filter systems because they have control of their pH and temperatures. This control (and obviously expensive complex equipment) allows them non-astringent beers and “into kettle,” efficiencies of over 100%.

Click to expand...

The two most influential factors affecting the extraction of tannins from malt into wort are pH and temperature. All-grain brewers are very careful not to allow wort pH to reach more than about pH 6 during sparging because tannin extraction increases with pH. In all-grain brewing wort pH typically rises during the last stages of wort collection and is one of the factors letting the brewer know that wort collection should be stopped.....

Temperature also affects tannin extraction. This relationship is pretty simple. If you don’t want to run the risk of getting too much tannin in your wort, keep the temperature just below 170° F.

This is where the answer to your last question begins. You ask whether steeping and sparging released "unwanted tannins" in your beer. For starters, all beer contains tannins. Some tannins are implicated in haze and some lend astringent flavors to beer.

The type most homebrewers are concerned about are those affecting flavor. In any case, it is up to the brewer to decide if the level of tannins in their beer is too high. The (in)famous decoction mash is frequently recommended when a brewer is in search of more malt flavor. Decoction mashes boil malt and — among analytical brewers who are not afraid of rocking the boat with unpopular ideas — are known to increase the astringent character associated with tannins. In general I wouldn’t consider 170° F dangerously high with respect to tannin extraction. However, if you believe your beers may suffer because of too much astringency, consider adjusting your steep pH and lowering the temperature a few degrees.

Click to expand...