Oliver Posted July 10, 2011 Share Posted July 10, 2011 Hi guys, There seems to be a bit of confusion about the reasoning behind the formula used to calculate the bitterness that cans contribute to an unfermented wort. I was hoping that you could clarify it for me as I haven't been able to find the answer by doing a search. In the Coopers Brewing FAQs you say that the formula is: Bitterness of can * 1.7 / final volume. So a Mexican Cerveza up to 23 litres would be: 270 x 1.7 / 23 = 20 IBU From this, I assume that the bitterness figure quoted on your website (270 for the Cerveza, for instance) is for 1kg of the product, hence the need to multiply by 1.7 because the tins are 1.7g? Looking forward to hearing from you. Cheers, Oliver Link to comment Share on other sites More sharing options...
NewtownClown Posted July 11, 2011 Share Posted July 11, 2011 In a word, exactly. As per the FAQ's * We use the weight because our quoted colour/bitterness figures are based on a weight/volume dilution. Link to comment Share on other sites More sharing options...
Oliver Posted July 11, 2011 Author Share Posted July 11, 2011 Thanks NewtownClown. I must say though that while I don't think I'm exactly a dunce, the phrase "our quoted colour/bitterness figures are based on a weight/volume dilution" isn't the height of clarity! It may as well be in Greek [smile] Coopers guys, how about simply saying "our quoted colour/bitterness figures are for 1kg of concentrate"? That would make it clear and unambiguous for all and sundry? Sorry, it's the journalist in me ... Link to comment Share on other sites More sharing options...
PB2 Posted July 11, 2011 Share Posted July 11, 2011 There's no confusion here, Oliver [sideways] Extract, being quite thick at around 80-81 Brix, is treated as a solid rather than a liquid. Therefore, our laboratory measures extract samples by weight rather than volume. This is why the FAQ recommends that the bitterness and colour figures are multiplied by the weight in the can rather than the volume. Link to comment Share on other sites More sharing options...
PB2 Posted July 11, 2011 Share Posted July 11, 2011 In response to an email requesting further clarification on this topic, I offer the following: In Oliver's OP, the quoted formula is not quite correct. He says, "Bitterness of can*1.7/final volume." The formula is - Product bitterness x 1.7 / Brew volume = Brew Bitterness before fermentation It is bitterness of the product and not bitterness of the can. It's important that we are as technically correct as possible when quoting our product specifications because these same figures are also supplied to customers who are commercial brewers. [rightful] Beer Fact - IBUs are expressed in milligrams (mg) of isomerised alpha acid per litre. So, a 375ml bottle of beer with a bitterness of 28 IBU will yield 28 * 0.375 = 10.5mg of iso-alpha acid. However, in the case of extracts, both hopped and un-hopped malt extract, we determine the Bitterness and Colour by preparing and measuring a 10% solution weight/volume. As said before, we dilute it in this manner because thick product is measured out by weight rather than volume. Therefore, multiplying the quoted product IBU value by the weight - a typical beer kit can weighs 1.7kg - does not give the IBU of the product, rather the total amount of iso-alpha acid (milligrams) in the can. I guess, when it gets down to it, the formula is intended as a tool for brewers to formulate the estimated bitterness of the fermented brew. It's generally accepted that one does not need a high cognitive understanding of the science behind a formula in order to use it effectively. [biggrin] Link to comment Share on other sites More sharing options...
Guest Posted July 12, 2011 Share Posted July 12, 2011 In response to an email requesting further clarification on this topic, I offer the following: In Oliver's OP, the quoted formula is not quite correct. He says, "Bitterness of can*1.7/final volume." The formula is - Product bitterness x 1.7 / Brew volume = Brew Bitterness before fermentation It is bitterness of the product and not bitterness of the can. It's important that we are as technically correct as possible when quoting our product specifications because these same figures are also supplied to customers who are commercial brewers. [rightful] Beer Fact - IBUs are expressed in milligrams (mg) of isomerised alpha acid per litre. So, a 375ml bottle of beer with a bitterness of 28 IBU will yield 28 * 0.375 = 10.5mg of iso-alpha acid. However, in the case of extracts, both hopped and un-hopped malt extract, we determine the Bitterness and Colour by preparing and measuring a 10% solution weight/volume. As said before, we dilute it in this manner because thick product is measured out by weight rather than volume. Therefore, multiplying the quoted product IBU value by the weight - a typical beer kit can weighs 1.7kg - does not give the IBU of the product, rather the total amount of iso-alpha acid (milligrams) in the can. I guess, when it gets down to it, the formula is intended as a tool for brewers to formulate the estimated bitterness of the fermented brew. It's generally accepted that one does not need a high cognitive understanding of the science behind a formula in order to use it effectively. [biggrin] Arrr yep, like he said [alien] Link to comment Share on other sites More sharing options...
Muddy Waters Posted July 12, 2011 Share Posted July 12, 2011 It's generally accepted that one does not need a high cognitive understanding of the science behind a formula in order to use it effectively. [biggrin] I've always had problems understanding cognitives! They speak furny [whistling Link to comment Share on other sites More sharing options...
BakersAle Posted July 14, 2011 Share Posted July 14, 2011 I've always had problems understanding cognitives! They speak furny [whistling easy way to understand it muddy is drink six beers 1 after the other and it will come to you Link to comment Share on other sites More sharing options...
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