buttersd70
Beerbelly's bitch :)
- Joined
- 28/11/07
- Messages
- 3,550
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- 8
A glib remark by myself in another thread about not being happy with the hop utilisation in Beersmith got a curious reaction as to why? Personally, I've always felt that the IBU given in Beersmith, using the Tinseth calculation, is under what it should be.several people on the forums have noted at various times that they feel their beer is more bitter than what Beersmith is telling them. (Irrespective of any possibly perceived difference in utilisation between chill vs. no chill) Given that I brew English Milds, which due to the low gravity and the low hopping rates have a finer tolerance to any error on the IBU, it got me curious.so I took one of my recipes, and loaded it into Promash (trial version), keeping all the details exactly the same.what I found was that Promash gave me a higher IBU. (20.1 compared to 18.1. Now 2 IBU doesn't sound a lot, but taken in context of the low OG of 1035, and the low IBU to begin with, it's actually just over 10% difference, and that is reasonably significant. There's a fair difference between a 0.517 bugu beer and a 0.574 bugu beer)
So, curiosity got me and I decided to have a play, making direct comparison to Beersmith, and Glenn Tinseths calculator on his web page. Unfortunately, his metric one is on the blink, so I switched Beersmith over to US measures, and started punching in random recipes, varying the batch sizes, alphas, gravities and boil times, and comparing the results. I make the assumption that Tinseths calculator is based on whole hops, so all the testing I did had whole hops selected in Beersmith. I varied the batch sizes between (the gallon equivalent of) 20-25L, set all losses to 0 apart from evaporation, which was set to 9%, set the boil size as calculated from the boil loss, and took the boil gravities from the BG estimation in the efficiency calculator.
I did high gravity, medium gravity, low gravity, 60 min addition, 40min, 15 min and 2 min, varying the alphas between 5% and 10% throughout. What I found was that Beersmith consistently came in with lower IBU across the board, for each addition. Under the equipment details there is a 'large batch utilisation factor', which, by default, is set to 100% ...I found that by changing that to 111%, all of a sudden all the numbers added up, to within less than an IBU with Tinseths calculator (which rounds to the nearest whole number anyway).
Going back to the recipe that I compared between Beersmith and Promash, which used a combination of pellets and flowers, and changing this overall utilisation to 111%.....all of a sudden, the numbers matched. The 60 minute addition was off by 0.1 IBU, the 15 minute addition by the same amount, but in the opposite direction, and the total IBU was spot on to the decimal place between the two.
So from now on, I'll be keeping the overall utilisation at 111%.....
So, curiosity got me and I decided to have a play, making direct comparison to Beersmith, and Glenn Tinseths calculator on his web page. Unfortunately, his metric one is on the blink, so I switched Beersmith over to US measures, and started punching in random recipes, varying the batch sizes, alphas, gravities and boil times, and comparing the results. I make the assumption that Tinseths calculator is based on whole hops, so all the testing I did had whole hops selected in Beersmith. I varied the batch sizes between (the gallon equivalent of) 20-25L, set all losses to 0 apart from evaporation, which was set to 9%, set the boil size as calculated from the boil loss, and took the boil gravities from the BG estimation in the efficiency calculator.
I did high gravity, medium gravity, low gravity, 60 min addition, 40min, 15 min and 2 min, varying the alphas between 5% and 10% throughout. What I found was that Beersmith consistently came in with lower IBU across the board, for each addition. Under the equipment details there is a 'large batch utilisation factor', which, by default, is set to 100% ...I found that by changing that to 111%, all of a sudden all the numbers added up, to within less than an IBU with Tinseths calculator (which rounds to the nearest whole number anyway).
Going back to the recipe that I compared between Beersmith and Promash, which used a combination of pellets and flowers, and changing this overall utilisation to 111%.....all of a sudden, the numbers matched. The 60 minute addition was off by 0.1 IBU, the 15 minute addition by the same amount, but in the opposite direction, and the total IBU was spot on to the decimal place between the two.
So from now on, I'll be keeping the overall utilisation at 111%.....