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Post Mash gravity changes with Boiling time ???

piertous

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On a Weissebier recipe, my post mash density varies with boiling time (in the Session view). This doesn't make any sense to me. Increasing boiling time reduce the post mash density. Funny it doesn't do it on other recipe (infusion), but on this Weissebier it does. I have a mashing schedule of a Ferrulic rest, and a saccharification rest. I don't catch it???
 
This is because the program uses Brewhouse Efficiency to determine the gravity readings. It applies this efficiency to the total available sugars from the grain bill entered. This determines the end of boil gravity. It then works backwards to calculate your pre-boil/post mash gravity reading. Since you changed the amount of water which was boiled off (loss of volume being a function of time of boil), this means that the volume change dictates the beginning volume while the amount of sugar remains a constant. If you, as an example, have a profile with a 90 minute boil time, the volume is higher for the pre-boil than if you changed the boil time to 45 minutes. The amount of sugars remains the same, so the expected gravity reading post mash would be higher for the 45 minute boil time than the 90 minute boil time.
 
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Hi understand what you mean, but having a fixed mash efficiency, it should not changed. And why it doesn't do it on every recipes. I did an IPA yesterday, and if I changed the boil time from 60 min to 150 min, my post mash density stayed the same ???
 
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Read through my response again. BeerSmith does not work based upon a fixed mash efficiency. It works based upon Brewhouse efficiency, which is the amount of sugars from the grist which makes it to the fermenter. I doing this, the mash efficiency becomes a variable based upon the process losses of sugar.
 
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