Grain Reaper Brewing
how strong of a boil? does it matter?
  • frydogbrewsfrydogbrews
    11374.00 KarmaPosts: 28,585
    after a double brew day today, i was thinking about boiling. i was running low on propane and with my big banjo burner needs a pretty full tank to maintain pressure. so for the second beer it was a very light boil, not really breaking the surface. still about 210 degrees though.

    so, let's talk about boiling. does it need to be a rolling boil? if so, why? seems to me that 210 degrees woudl be plenty hot and totally unlikely to scorch anything, so its a win?

    thoughts?
  • FromZwolleFromZwolle
    6436.00 KarmaPosts: 28,376
    i usually keep mine to just barely boiling. the only real difference that i've encountered is the boil off volume.
  • frydogbrewsfrydogbrews
    11374.00 KarmaPosts: 28,585
    FromZwolle said:

    i usually keep mine to just barely boiling. the only real difference that i've encountered is the boil off volume.


    so what is just barely boiling?

    my kettle is large, so for me, i like to keep it where maybe every 3-5 seconds, a large bubble breaks the surface, but for the most part, the surface is flat and you can see the liquid moving beneath.
  • FromZwolleFromZwolle
    6436.00 KarmaPosts: 28,376
    frydogbrews said:

    FromZwolle said:

    i usually keep mine to just barely boiling. the only real difference that i've encountered is the boil off volume.


    so what is just barely boiling?

    my kettle is large, so for me, i like to keep it where maybe every 3-5 seconds, a large bubble breaks the surface, but for the most part, the surface is flat and you can see the liquid moving beneath.


    you can see the wort churning, but the surface is flat. there are small bubbles that push all the foam to one side, but no big bubbles.

    something like a low simmer.
  • ceanntceannt
    28927.00 KarmaPosts: 19,104
    Too hard a boil is bad ..... thermal loading ..... bring it to a good boil until it settles down, then turn down the heat to what is described above ..... that's my my motto
    From the sweat of man, and God's love.... beer came into the world
  • BenSBenS
    603.00 KarmaPosts: 3,297
    A stronger boil is suggested.

    Proof: http://bavarianbrewerytech.com/news/boilhops.htm
  • frydogbrewsfrydogbrews
    11374.00 KarmaPosts: 28,585
    BenS said:

    A stronger boil is suggested.

    Proof: http://bavarianbrewerytech.com/news/boilhops.htm


    i read it, but i'm not convinced. a 3-5 degree difference shouldn't matter for any of the reasons they listed.

    also, the point about driving out the oxygen is silly.

    boiling hard enough to drive off 5% is easily achieved with a violent boil.
  • ceanntceannt
    28927.00 KarmaPosts: 19,104
    I have read for years how important it is to maintain a good hard rolling boil ...... I call BS ...
    that is a sure way to end up with DMS and other off flavors ... especially with lighter malts like pilsner .... a longer boil ... say 90 minutes ... at just barely boiling is way better
    From the sweat of man, and God's love.... beer came into the world
  • ceanntceannt
    28927.00 KarmaPosts: 19,104
    Thermal loading and a fast chill together is the devil!
    From the sweat of man, and God's love.... beer came into the world
  • BenSBenS
    603.00 KarmaPosts: 3,297
    ceannt said:

    Thermal loading and a fast chill together is the devil!



    What do you guys mean by thermal loading? Once water reaches a boil at a non changing surrounding pressure, the enthalpy of the water does not change no matter how vigorous of a boil it is.
  • BenSBenS
    603.00 KarmaPosts: 3,297
    Water also does not go above its boiling temperature. It simply becomes vapor. Which can be much hotter.
  • ceanntceannt
    28927.00 KarmaPosts: 19,104
    BenS said:

    ceannt said:

    Thermal loading and a fast chill together is the devil!



    What do you guys mean by thermal loading? Once water reaches a boil at a non changing surrounding pressure, the enthalpy of the water does not change no matter how vigorous of a boil it is.


    Wort isn't just water ..... the particles in suspension can reach temps above 212.... way above ....
    From the sweat of man, and God's love.... beer came into the world
  • ceanntceannt
    28927.00 KarmaPosts: 19,104
    That is why wort boils so crazy hard ... with huge big bubbles .... the water turns to vapor like mad since the suspended material is hotter than the water ...
    From the sweat of man, and God's love.... beer came into the world
  • ceanntceannt
    28927.00 KarmaPosts: 19,104
    And why I say its important to insure that the non water components don't go over 212
    From the sweat of man, and God's love.... beer came into the world
  • ceanntceannt
    28927.00 KarmaPosts: 19,104
    This is more important for bigger beers .... not so much for bud light clones ....
    From the sweat of man, and God's love.... beer came into the world
  • ceanntceannt
    28927.00 KarmaPosts: 19,104
    Remember ... specific gravity
    From the sweat of man, and God's love.... beer came into the world
  • BenSBenS
    603.00 KarmaPosts: 3,297
    A 10 per cent solution of sugar is one that contains 10 grams of sugar and 90 grams of water or one having these proportions.

    Read more: http://chestofbooks.com/food/science/Experimental-Cookery/The-Boiling-Point-Of-Water-And-Solutions.html#.UStzH6XCaSo#ixzz2LvA5U8QV


    Let's assume that 10% of the weight of the wort is solubles that have come from the mash, which I think is realistic. Of course it could be lower or higher depending on the beer being produced. I also realize that we aren't pulling straight sucrose from the mash but it puts us in the ballpark.

    The above listed website has a chart that shows that a 10% sugar(by weight)/water solution has a boiling temp of 100.4C, 20% sugar/water = 100.6C. Not much difference from water.

    None of that explains the idea of thermal loading. From the same website above,

    If a thermometer is held in the liquid it is found that when this point is reached the temperature is constant. This is the boiling point. A child might say that when a liquid is bubbling it is boiling, and it would be a fairly good definition. However, the chemist or physicist would word his definition differently. With vapor formation, pressure is exerted. Since the bubble is less dense than the liquid it comes to the surface. But the bubble cannot reach the surface until the pressure within it is just a little greater than the pressure of the liquid on the bubble. The pressure on the bubble in an open pan comes from the weight of the column of liquid above it and the atmospheric pressure on the surface of the liquid. Another way to define the boiling point is to say that it is the temperature at which the pressure of the saturated vapor within the liquid is just greater than the outside pressure on the surface of the liquid.

    Read more: http://chestofbooks.com/food/science/Experimental-Cookery/The-Boiling-Point-Of-Water-And-Solutions.html#.UStzH6XCaSo#ixzz2LvCyP1sl


  • BenSBenS
    603.00 KarmaPosts: 3,297
    No matter how hard you boil a liquid, it will not raise the temp above the 'boiling temp'. This is because the pressure of the saturated gas in the liquid will be released to the atmosphere as soon as its pressure is greater than the atmosphere. This is the basis of pressure cookers. They raise the pressure of the vapor above the liquid in the pot, thereby increasing the pressure of the staurated vapor in the liquid and the resulting temperature of the liquid is raised to ~250F at 15psi.
  • BenSBenS
    603.00 KarmaPosts: 3,297
    frydogbrews said:


    i read it, but i'm not convinced. a 3-5 degree difference shouldn't matter for any of the reasons they listed.

    also, the point about driving out the oxygen is silly.

    boiling hard enough to drive off 5% is easily achieved with a violent boil.



    The temperature difference between a simmering pot of wort and a 'violently boiling' pot of wort is not 3-5F, it is very minimal.

    Boiling water does drive out oxygen, I don't know the exact reason why it's important for brewing, but there's no argument that boiling does reduce the % of oxygen dissolved in water. Of course, lots of oxygen is also re-absorbed into the water when cooled.......

    A 5% evaporation rate is easily achieved
  • morsmors
    130.00 KarmaPosts: 46
    The only real reason for a rolling boil is to drive off DMS and to further evaporate water if that is your desire. A low boil you will drive off less DMS.
  • ceanntceannt
    28927.00 KarmaPosts: 19,104
    mors said:

    The only real reason for a rolling boil is to drive off DMS and to further evaporate water if that is your desire. A low boil you will drive off less DMS.



    You actually drive off less DMS if the boil is too strong .... this is why the Belgians "simmer" their wort. I noticed a huge difference in my beer after I read "brew like a monk" and stopped boiling the hell out of my wort.
    From the sweat of man, and God's love.... beer came into the world
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