Mash-out and wort fermentability
 

Does a direct-heat mash-out (taking about 10-15 min. on a 10-gallon batch to go from 150-something°F to 168°F) result in a slightly less fermentable wort (although with slightly higher efficiency) compared to a batch sparged no mash-out or a hot water infusion or decoction mash-out that doesn't spend that extra time in the alpha-amylase temperature range?

Over a year old and no answer? I found this at the bottom of another page. I was thinking the same thing. Any answer from anyone smarter than me?

efficiency wont be affected as conversion should be complete by that point. attenuation may be, but thats cuz you're denaturing enzymes with a mash out where as the other way you're still letting the amylase chop up sugars

Fermentability and attenuation are set by the main mash. The mash out step does not affect that. Although, the mash out does denature the remaining enzymes and stop any further starch and sugar conversion.

But, the mash out does have a significant effect on the efficiency of the mash. You will get several points more extract from the mash when performing a mash out.

Raising the wort to 168-170 does not denature the alpha-amylase. It will keep working. The beta will be denatured, so the alpha will be breaking up longer dextrins into medium dextrins, which may be fermentable.

As to the original question, raising the temperature above 162 will denature the beta amylase, which will significantly decrease the formation of maltose, and lead to a less fermentable wort. However, if you spend enough time before raising the temp., the effect will probably be minimal.

As temperature is unrelated to efficiency, can you please explain how a mash out could raise your efficiency.

There's two ways a mash out might increase efficiency. First, if you really were not fully converted, the early stages of a mashout ramp up will peak beta amylase and increase alpha activity also. Of course, it's relatively short lived but if you were at 95% conversion before the mashout, you may end up with 98% by the end. Second, the slight increase in sugar solubility at higher temps may increase lauter efficiency. Kaiser messed with cold sparging a bit and may have at least partially busted the latter claim so it's less influential if at all.

I thought maybe the higher temp might liberate some starch that otherwise would not have been and since the alpha is not fully denatured (as pkeeler mentioned) those newly liberated starches would get converted.

I think it may depend what temp your mash was before the mashout...big difference between 148* F and 158* F.

I don't think an extra 10 min heating from 150*-something to 168* would make much difference in fermentability but I'm just shootin' from the hip. I usually either mash-out via direct-heat, infusion, or thin-mash decoction (almost always one of the three) and don't notice a difference.

Ah, temperature is directly related to starch and sugar extraction from the grain, thus the improvement in extract that is evident when performing decoction mashing. Additionally, I have performed over a hundred RIMS mashes and have observed 'many' points of increased gravity with my refractometer with before and after mash out samples (I say 'many' since I don't have my brewing logs in front of me).

Anyone that does not perform a mash out step is leaving some efficiency behind.

sure mashing out increases your efficiency out of your first runnings, but does your overall efficiency change with and without a mash-out? even if it did increase it by a few meager points, they're highly unfermentable and thus mostly useless added points. aside from causing the alpha amylase going into hyper mode and converting whatever starches are left, the mash out doesnt add any sugars that your sparge wouldnt.