Over-sparging with 5.2 ph sparge water

I've been using a step infusion mash with my water cooler MLT but over sparged on a recent batch (dough-in had too much water and it spiraled from there...) I got great efficiency (around 93%) from the over-sparging but am worried about astringency from the tannins. Unfortunately I did not read the gravity of the final runnings so I'm not sure how low I got but I know it was low as I was running this pretty thin.

The reading I have done describes the tannin leaching as resulting from the ph increase of the mash. So I'm curious, how much of a concern is over-sparging if one uses ph corrected (say 5.2) sparge water?

I like the efficiency that the over-sparge creates, but certainly not at the cost of astringency (haven't tasted the beer yet to know as it has another week to go before bottling). Certainly another downside is the longer boil time to get to the target volume.

Cheers,
-Brad

Rdwhahb

The sparge water pH should not typically be below about a pH of 5.5 for most waters. Sparge water pH typically falls between 5.5 and 6.0 and its really the resulting alkalinity of the treated sparge water that is the controlling factor with regard to tannin extraction potential. Keeping the sparge water alkalinity around 20 ppm or less seems to be a good target. You can read more about sparge water treatment in Bru'n Water.

A more important factor in avoiding tannin extraction is avoiding oversparging. That means keeping a better assessment of the runoff gravity. Proper treatment of sparge water only improves the cushion against tannin extraction, but can't prevent it.

Hi Martin,

Thanks for your reply. I certainly have a lot to learn about water chemistry and look forward to learning what I need to do with my local well water to make the most of it for my brewing. Thanks for pointing me to your Excel application, I've just sent a couple of samples of my water (softened and untreated) to Ward labs for analysis. I'm expecting that my untreated well water will be the best to use but I expect it to be hard and was hoping that I could make certain styles with the untreated water (e.g. stouts) and others with the softened water (e.g. pilsners), but after a bit of reading I'm not sure my treated water will be suitable to use. The results from Ward Lab should tell me for sure.

But back on the topic of sparging. I agree that it's best to avoid the over sparge, but when step infusion mashing it's easy to use more water than desired. So (and I'm sure it's not as simple as this), is 1.010 generally considered the lower limit on the SG of final runnings? i.e. one should avoid going below this value? What is the maximum efficiency that one should expect when sparging to this gravity?

BTW, I sampled my stout (made with my untreated well water) when I took my gravity test yesterday and I'm pleased to report that it's not at all astringent. Yay! It goes in the keg next weekend.

Cheers,
-Brad

Geigon said:

Hi Martin,
I'm expecting that my untreated well water will be the best to use but I expect it to be hard and was hoping that I could make certain styles with the untreated water (e.g. stouts) and others with the softened water (e.g. pilsners), but after a bit of reading I'm not sure my treated water will be suitable to use. The results from Ward Lab should tell me for sure.

Click to expand...

Softened water..... as in water that's been run through a water softener? If so, it will be unsuitable for brewing anything. What a water softener does is remove many of the minerals we need for brewing, and replace them with large quantities of either salt or potassium depending on the type of softener. Large quantities of either are bad for brewing. If your water is hard and suitable for darker beers, you'd want to dilute it with RO or distilled water for brewing lighter beers. The "softened" water should never come into play.

As far as preventing tannin extraction from oversparging, the best option as mentioned above is to simply avoid oversparging. As long as you're only collecting enough to reach your pre-boil volume, oversparging should only be a concern for low gravity session beers. You're already aware of two huge downsides to collecting more than you need, so why do it? Let's say oversparging increases your efficiency a few points. Is buying an extra 0.5# of grain really worse than an extra 30 min of boil time and the risk of tannin extraction? If you can't avoid the issue somehow and you're having issues with the ph of the late runnings, I'd use an acid (lactic, citric) to adjust it rather than a bunch of buffers known as 5.2.

Thanks, Juan, for the feedback on my question about softened water. I'll definitely avoid this, and look at correcting my well water using other beer friendly means like those you suggest.

Regarding my question about oversparging and tannin extraction I'm looking for better understanding of the sources of astringency and tools for how to handle various situations such as this. I was fortunate in this case to avoid astringency, and was surprised at the efficiency that I got so this got me thinking...

I'm actually not quite sure what is the common accepted definition of oversparging. Is it?

A) Using more sparge water than 2.5 qts/lb of grain in the mash (or some other quantity/lb of grain).
B) Using sparge water that yields more than your target pre-boil volume.
C) Using sparge water that starts to extract tannins and cause astringency.
D) Using sparge water that yields a final running SG of less than 1.010 (or some other SG).
E) Something else.

Definition B doesn't feel right to me for the following reason: if my mash efficiency was really good (I overshot my expected efficiency), if I stop at the target pre-boil volume I will have a higher OG than desired. So I could: 1) Stop at the pre-boil volume target and just add water to correct the gravity, or 2) continue the sparge with ph corrected water to get to the desired gravity. My intuition is that option 2 should yield (a bit) more beer (more beer = good , and if the ph of the sparge water has been corrected does one run a high risk of extraction tannins?

Does this line of questioning make sense? Just to be clear, I'm not trying to advocate a different method or approach, just trying to understand oversparging better and the risks of tannin extraction.

Thanks for the discussion.

Cheers,
-Brad