I was wondering something. When I brew beer, I mash my grain for an hour or so at 60-70oC. I then separate the wort from the grain. Then I add hop into the boiling wort for 90 minutes.

My friend told me that he is doing his hopping boil for with the grain still in the mashtun. I mean after the mashing part, instead of separating the grain and the wort, he leaves the grains in the mashtun. He then proceed to add hops in this boiling mixture of wort and grain.

Is that bad or people do this ?


  • I really don't understand what you are saying your friend is doing. "boil for hopping with the grain still in" can you edit that to make it more clear. Maybe its just me.
    – brewchez
    Dec 9, 2015 at 22:04
  • corrected, hope this help better understand what i meant! Maybe what is unclear is that i feel its very weird practice so even with correct wording it could not have made sense to you!
    – MastaJeet
    Dec 9, 2015 at 22:11
  • 1
    Have you tasted this friends beer before?
    – brewchez
    Dec 10, 2015 at 12:41
  • That is a very good question and no not yet but he has been producing over a year. He'S going to give me samples during the holidays!
    – MastaJeet
    Dec 10, 2015 at 12:54
  • No trouble MastaJeet. Brewchez, you shouldn't presume what others have or have not tried. It was not indicated that no astringency would come from decoction. Yes pH plays an important part in tannin extract and so does temperature, and they act independently with symbiotic increase of extraction when both variables are supporting tannin extraction. Keep in mind boiling grain for 90 min per question is very different than just long enough to achieve homogenous temp with decoction.
    – John
    Dec 10, 2015 at 15:34

3 Answers 3


Raising the mash above 78 C generally runs the risk of extracting polyphenols, which will add astringency to your beer.

Additionally you'll extract other compounds that will make having a clear product more challenging.

Boiling with grains can be done if your boiling a small portion of your mash and returning it to increase the temperature of the overall mash. This is known as decoction mashing.

You can add hops to your mash, you will derive some benefits from this. Keep in mind the solubility and extraction of your alpha acids will be lower unless boiling and any oils and flavour compounds extracted will be volatolized inn the boil.

Would not recommend boiling your mash (grains)

  • Thank you for your answer! I'll make sure to have a chat with my friend !
    – MastaJeet
    Dec 9, 2015 at 19:13
  • 4
    If decoction doesn't add astringency to the beer then why would boiling the whole thing? Usually in most decoctions half or more of the grain is pulled and boiled. I don't think that statement is correct. The pulling of polyphenols is usually a pH driven thing not temperature alone. I still don't think boiling the whole thing is a great idea, but if you haven't tried it then you don't know.
    – brewchez
    Dec 10, 2015 at 12:40

Boiling the grain will add a LOT of starch and fiber into suspension. I wouldn't do it, though I guess if you are after a specific character that can only be had through boiling your grain, then I'd go for it. I would imagine this will be hard on clarifying and make you burn through more filters, if you do filter.

  • If the boiling is done post starch conversion/mash then there shouldn't be a problem with starches getting into the beer.
    – brewchez
    Dec 10, 2015 at 12:41
  • I was under the impression that the regular mashing could only get / convert like 60%-80% percent of the available starch. wouldn't the boiling help extracting whatever is left (and of course not transfering it to fermentable sugar since temperature killed the enzyme responsible for cutting starch?)
    – MastaJeet
    Dec 10, 2015 at 12:57

Sounds like your friend is doing a decoction ( a way of stepping up the mash temp by boiling some of the grist then adding it back to the mash) this also adds some classic characters to styles, like dopplebock. Boiling grain is safe from tannis since it is only done once the mash is below 6.0 pH. Tannin extraction needs two things temp above 170° and a pH higher than 6.0.

As far as the hops in the mash, it's simular to first wort hopping. Some Pliny clone recipies I've seen call for some of hops in the mash.

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