MatRat
New Member
So yesterday I did my first full boil AG batch. At the moment, Ive got two kettles, one with 5 gallons capacity and the other 4 gallons (i.e. neither with enough to do a full boil). In the past, as a solution to this conundrum, Ive done smaller boils and added DME at the end of the boil + topped up fermenter with water to hit my intended batch size (5 gallons).
This time around I opted to do two separate boils: one with the first runnings from my mash tun and one with my second runnings. The S.G. of my first runnings (at 76 F) was 1.062, while the S.G. of my second runnings (at 86 F) was 1.030 (I realize this is entirely indicative of inefficiencies in my mash process but that is another story) and the boils were approx. 40 min staggered apart which gave me enough time to chill the wort from the first boil prior to the completion of my second boil.
One outcome I realized this would have on my finished beer was the IBU utilization rate. For instance, lets assume the following: (i) an estimated boil-off rate of 12.50% / hr; (ii) starting total boil volume of 6.25 gallons; (iii) starting boil gravity of 1.049; and (iv) four additions of 10% AA hops at 60 min (1 oz), 30 min (1/2 oz), and 15 min (1/2 oz). My estimated IBUs in the resulting beer is 46.
Now, if I adjust for two boils (one with an initial volume and gravity of 2.8 gallons and 1.063, respectively; and the other with an initial volume and gravity of 3.4 gallons and 1.032, respectively) and the same hop schedule just split in half for each boil, the IBUs of my first boil come out to 45 and for my second boil come out to 50, for a weighted average of 48. Now I wouldnt consider a difference of 2 IBUs anything to write home about, but consider if I had been able to better manage the sugar extraction in my first runnings and assume that my second runnings were at 1.015. Under the same scenario, the IBUs of this second boil would go up to 59. Furthermore, if one were to put ¾ of the hop additions into that second boil, its estimated IBUs would increase to 88!
Out of this, my question then becomes whether there is any downside to this method, aside from running two separate boils (and consequently having to watch for two boil-overs as well as chilling two kettles rather than one), what disadvantages are there to running two separate boils like this?
This time around I opted to do two separate boils: one with the first runnings from my mash tun and one with my second runnings. The S.G. of my first runnings (at 76 F) was 1.062, while the S.G. of my second runnings (at 86 F) was 1.030 (I realize this is entirely indicative of inefficiencies in my mash process but that is another story) and the boils were approx. 40 min staggered apart which gave me enough time to chill the wort from the first boil prior to the completion of my second boil.
One outcome I realized this would have on my finished beer was the IBU utilization rate. For instance, lets assume the following: (i) an estimated boil-off rate of 12.50% / hr; (ii) starting total boil volume of 6.25 gallons; (iii) starting boil gravity of 1.049; and (iv) four additions of 10% AA hops at 60 min (1 oz), 30 min (1/2 oz), and 15 min (1/2 oz). My estimated IBUs in the resulting beer is 46.
Now, if I adjust for two boils (one with an initial volume and gravity of 2.8 gallons and 1.063, respectively; and the other with an initial volume and gravity of 3.4 gallons and 1.032, respectively) and the same hop schedule just split in half for each boil, the IBUs of my first boil come out to 45 and for my second boil come out to 50, for a weighted average of 48. Now I wouldnt consider a difference of 2 IBUs anything to write home about, but consider if I had been able to better manage the sugar extraction in my first runnings and assume that my second runnings were at 1.015. Under the same scenario, the IBUs of this second boil would go up to 59. Furthermore, if one were to put ¾ of the hop additions into that second boil, its estimated IBUs would increase to 88!
Out of this, my question then becomes whether there is any downside to this method, aside from running two separate boils (and consequently having to watch for two boil-overs as well as chilling two kettles rather than one), what disadvantages are there to running two separate boils like this?
