AG and Tannins. What can cause tannin extraction with AG brewing?

[Jayhem]

So recently I've come across some information on this site that leads me to believe the following may be risks of tannin extraction when AG brewing.

1. Too hot a sparge water temp?

2. Sparging with too much water?

3. Crushing the grain too fine or without conditioning the grain may extract tannins in the mash?

Any truth to any of these? Educate me!

 

[passedpawn]

So recently I've come across some information on this site that leads me to believe the following may be risks of tannin extraction when AG brewing.

1. Too hot a sparge water temp? No


2. Sparging with too much water? Yes

3. Crushing the grain too fine or without conditioning the grain may extract tannins in the mash? No

Any truth to any of these? Educate me!

High pH causes tannin extraction.

What causes the pH to get too high? Over-sparging. Not a problem if you are batch sparging with 1 or 2 sparges. But if you sparge 3 or more times, or are fly-sparging, the pH can rise to the point where the astringent tannins get pulled out of the husks and into the wort.

The mash sits at a relatively low pH (acidic). As you sparge, the specific gravity of the mash goes down (of course), and the pH increases towards pH = 7. You could measure pH and stop sparging if it gets over pH=6.0. Or, you could watch the gravity (with a refractometer) and stop sparging if the mash gravity falls below 1.010. I'm not sure if those are the best numbers because I don't do any of that

 

[Jayhem]

Low pH causes tannin extraction.

You're telling me that 175F sparge water would be no worries?

What causes the pH to drop? I have a neutral water pH but I'm sure the grain effects that.

 

[cheezydemon3]

Just PH. AG?

PH of water to begin with may be low.

 

[janivar123]

After what i have heard/red you need to combine 1 and 2 to get too high temp and high pH
Effect is the same too much water but its high pH not low...

 

[passedpawn]

You're telling me that 175F sparge water would be no worries?

What causes the pH to drop? I have a neutral water pH but I'm sure the grain effects that.

I edited my post. Sorry, prematurely posted before I was done typing.

 

[brewit2it]

I edited my post. Sorry, prematurely posted before I was done typing.

Good info. So let me ask you this, when doing BIAB most (myself included) dunk sparge the grains in a fairly large volume of heated water at the end of the mash. Since the majority of the fermentables are already drained into the primary kettle I would think the SG of the dunk sparge kettle could be quite low. Would this be a risk for tannin extraction or would the large volume of water we are dunking into help buffer against a high pH?

 

[Jayhem]

Ok, so it's all about high pH and pH rises as the SG of the runnings gets lower.

What is the easiest tool to check the pH and where would you measure it?

If my runnings are getting too high in pH is there something I can add to the mash to lower the pH?

What is considered a pH that could cause tannin extraction? 6.0? 6.5? 7.0?

 

[TopherM]

What is considered a pH that could cause tannin extraction? 6.0? 6.5? 7.0?

Most of the brewing knowledge I've read says tannin extraction starts above 6.0 PH at a minimum temperture of 37C (99F). I've also read that it is very difficult to extract tannins from Pale Malts, as they pretty consistently create and maintain a 5.4 PH environment as part of the mashing process.

 

[broadbill]

Good info. So let me ask you this, when doing BIAB most (myself included) dunk sparge the grains in a fairly large volume of heated water at the end of the mash. Since the majority of the fermentables are already drained into the primary kettle I would think the SG of the dunk sparge kettle could be quite low. Would this be a risk for tannin extraction or would the large volume of water we are dunking into help buffer against a high pH?

I'd be surprised if you were getting enough gravity dilution during BIAB to get tannin extraction.

 

[Homercidal]

I'd be surprised if you were getting enough gravity dilution during BIAB to get tannin extraction.

I agree, however your water profile and grain bill both play a significant part in how this all goes down. If you have highly alkaline water and are using a very pale grain bill and a low portion of it too, then there is a good chance you might not have enough buffer in your grain to prevent the pH from reaching 6.0.

Keeping the sparge temperature down is one way to help. I have recently read that experiments show that there is negligible loss in efficiency in using a slightly cooler sparge water.

 

[Jayhem]

I agree, however your water profile and grain bill both play a significant part in how this all goes down. If you have highly alkaline water and are using a very pale grain bill and a low portion of it too, then there is a good chance you might not have enough buffer in your grain to prevent the pH from reaching 6.0.

Keeping the sparge temperature down is one way to help. I have recently read that experiments show that there is negligible loss in efficiency in using a slightly cooler sparge water.

What temp sparge water would be "slightly cooler"? 160F? When we say "sparge water temp" are we talking about the temp of the water being poured into the mash tun or the temp of the mash during sparging? I've read conflicting information on this. If I sparge with 165F water the temp of my mash during the sparge drops by about 5 degrees to 160F.