BIAB and Hop Utilization

[hatbert]

I've done many batches of 5-6 gal BIAB brews with fairly consistent efficiency around 75-80% and have produced some decent beers. However I've always felt something was a bit off, beers tasting too sweet even though the final gravity was low, and something always felt missing but I couldn't quite put my finger on what.

A couple of weeks ago it finally hit me, I've been getting almost no bitterness in my beers, even in the ones with heavy hop additions. I'm not sure why I didn't realize this sooner after making IPAs which should have IBUs in the 80s and not getting that bitter punch.

So I've just switched over to a mash tun with false bottom and have completed 2 batches so far. One a simple kolsch and today an IPA. Immediately I can taste the difference and recognize the bitterness in the beer.

I guess my question is what would cause me to get such poor hop utilization with my BIAB batches? The only difference I can think of is the clarity of wort before I begin my boil. Could all the extra trub and particles from the BIAB mash somehow be removing the alpha acids or preventing isomerization?

 

[pricelessbrewing]

Already replied on reddit.

This.

Gravity effects hop utilization, but there's not really anything inherent in BIAB that would affect utilization as far as I'm aware.

However pretty much every study uses closed boil vessels so pressure is also increased somewhat. Not really known how evaporation itself effects utilization. Moreover boil off rates effect utilization since the gravity changes over time at different rates depending on the boil off rate. I've done some math modelling to a certain extent I can estimate it (it's a tiny difference for most setups unless you have a high boil off), no academic or professional studies have been done as far as I'm aware. Surface area has also been linked to IBUs in some papers, not so much of the hop utilization but because a certain % of the isomerized oils remain behind on the surface of the pot after the wort is pulled.

With all that said, tinseths formula is pretty accurate for the most part, except for above 75~ ibu where you hit a solubility limit depending on ph. Either way, 75 IBUs 150 ibu are both going to be rather bitter.

 

[slym2none]

Yeah, it isn't the BIAB part that is causing your issues. IDK what it is, but it definitely isn't the BIAB method.

 

[akthor]

How do you add hops to your BIAB? Loose in the bag or some sort of secondary bag or hop spider or some such?

 

[slym2none]

BIAB only happens during the mash. Even FWHing happens after the bag is pulled. During the boil, whirlpool/hopstand, and dry-hops, I just toss my hops in "naked".

 

[Oginme]

Already answered in your Reddit post but to elaborate:

The Chloride to sulfate ration in your water makes an impact on the perception of malt flavors (higher Chloride) or hop bitterness (higher Sulfate).

Want to test it? Take a very small pinch of gypsum (looking for about .07 grams) and put it in the bottom of a beer glass. Pour one of your beers into it and another into a clean glass. Let them sit for five minutes and then taste them. If the glass with the gypsum is considerably bitter, then that is your issue.

 

[akthor]

Sorry wasn't thinking it was late. But you are just putting them in "naked" so that's not the issue.

BIAB only happens during the mash. Even FWHing happens after the bag is pulled. During the boil, whirlpool/hopstand, and dry-hops, I just toss my hops in "naked".

 

[m00ps]

This thread has me very confused. Before, were you like tossing in your hops during the mash? Or boiling your malts?

 

[Foosier]

If you have not determined how your water is affecting your beer, you are missing the most likely culprit. Water plays a huge role in the taste perception of your beer. And we are not talking about bad tasting water = bad beer. We are talking about the ion concentrations (Sulfates, chlorides, etc...). These really make a big difference in your perception of bitterness and malty flavors. Additionally, if you do not know your water you are likely also having mash PH issues.

Take a look at the brewing water stickies in the Brew science forum. Tons to learn there, but it all starts simply enough. but this is one of the biggest areas where you can make siginificant improvements to your beer. Without doing this, it really won't matter how you mash.

 

[slym2none]

This thread has me very confused.

Me too...