Nothing. You won't notice a bit of difference.

 

I only mash out when I batch sparge, otherwise in my no sparge batches it goes straight into the kettle to get boiled.

 

It won't make a bit of difference.

 

You may loose a little efficiency, the enzymes are active for a time at 168-170 and then denature fairly shortly at that temperature. There are some dextrins formed at higher temps that may contribute to mouthfeel and head retention.

 

At 156 for 75 minutes I doubt there'd be enough left to make a distinguishable difference unless the crush was pretty coarse.

 

I suppose more properly, at our scale you won't notice any difference. I've done batches with and without a mashout and have not noticed a difference in efficiency. I suppose if you did enough of them, there might be a statistically significant difference but that would be more a function of the number of batches than any actual benefit from doing a mash-out.

 

I wonder if the temperature is more important than the added volume of water in an infusion addition. I think that by loosening up the mash thickness, it allows easier rinsing of sugars. The temperature difference may or may not contribute but as BOB says, it's likely that enzymatic conversion is pretty wrung out if we're staying at it for extended periods. By the time we're let it sit for over an hour, there's probably not any enzymes to denature.

 

I think mash-out is a control mechanism big brewers use to create uniform worts, all things considered. It would not improve efficiency - you're actually destroying enyzmes that might convert a few more molecules of starch to sugar and if that were the case, the big guys wouldn't do it. As to loosening up the mash thickness, our sugar solutions aren't saturated enough that 10 degrees Fahrenheit is going to make much of a difference in viscosity. I've even read (not that I intend to try it) that heating the sparge water isn't necessary. A lot of things that matter if you're trying to make the next million gallons of Coors taste like the last million just don't matter at our scale and I think mash-out is one of those things.

 

Agreed...That's why I think that the mashout in an step-infusion situation would be more likely to make a difference based on the added (boiling) water volume added to raise the temp, not the temp itself. Just raising the temp and leaving the water volume the same isn't likely to have much of a bearing.
And, yes, I think it's a big-brewer thing. I still do it out of habit. I hate messing with good results.

 

It does improve efficiency, it’s simple to check, the gravity increases. Enzymes are still active as high as 168F, they will begin to denature at that temperature fairly quickly. If all the starches are converted at lower temperatures, there wouldn’t be a gravity increase and conversion rates of 90% would be common and easy to hit.

That being said, mashout can be skipped without much of an affect on the beer. I prefer to mashout for two reasons. Clearer wort, which leads to clearer beer and more complete conversion. If you can mashout simply by turning up the temperature on the controller, why wouldn’t you? If you had to try to add the correct amount of boiling water to hit the right temperature, it might be a lot easier to skip. It could be a real PITA

 

I recently changed my mash process as follows

• Mash at.1.3 qt per lb at whatever mash temp for 60 minutes
• Add boiling water to raise temp to 168. Stir good and rest for 10 minutes
• Drain to Kettle as fast as possible
• Add remaining water at 168. Stir well and rest for ten minutes.
• Drain to Kettle as fast as possible

Since making this change my typical Kettle and brew house efficiency have jumped ten points to 91% and 77% respectively.

My brewhouse is low because I leave a gallon of trub/wort in the kettle.

 

Coincidentally, I changed my mashout procedure this last brew in hopes to tame some harshness* I picked up on the last brew of the same recipe. And judging by a sample at fermentation completion, I can taste a difference in the harshness* already. Previously, I added boiling water (a lot) to raise from mid 150’s (f) to 168 (f). I wondered what the boiling water would do to the grains until it attenuated down to 168. This latest brew, I sparged with 168 (f) water only, and the harshness is gone. All this with no effect on efficiency.

I’ve heard and read that anything over 170 (f) can yield an astringency characteristic.

* harshness... it’s an IPA, but since going with boiling sparge, I’ve noticed a slight increase.

Sorry for straying abit off topic, but the discussion was heading that way

 

Another reason for raising mash temp to mash out is less time to reach boil.
I too do a 75c "mash out" every brew.

 

When I did BIAB I never did a mash out. Since I switched to all grain, and mashing in a cooler I have been adding boiling water to do a mash out rest for 10 minutes, then a batch Sparge with the balance of the water at 170 with a 10 minute rest. I have been wondering if it would be better to do a first runnings with 1.5qt/lb mash, then do a batch Sparge with the balance of the water. Skip the mash out step...

 

For batch sparging the best results are said to come from getting half of the wort from first runnings and the other half from the sparge. I've found that anything close to that will net good results. In the past I have done boiling infusions for a mashout and didn't gain a thing. Now, it's the KISS method with good results.

 

I use cold water for the Sparge. No difference from heating to 170 or whatever google is suggesting currently.

 

Interesting, hope you don't mind if I pursue this a little further jmac...

So Bob, if my total water volume is 8.6 gallons, with 12.6 lbs of grist, mash thickness 1.5g/lb, strike 4.7g, should I just do a batch Sparge with the balance of the water after first runnings?

 

That's why I mash at 1.3qt/lb. Doing that makes the mash + mashout equal roughly half of the entire volume leaving the other half for sparge. Truth be told I don't ever hit 168 for the mashout. For some reason the mash calculator always leaves me three or four degrees short.