tag:blogger.com,1999:blog-8081751738815878503.post3465162696306462041..comments2023-04-14T03:40:29.342-04:00Comments on Sui Generis Brewing: Brewing Science: Gelatin & Clearing BeerBryanhttp://www.blogger.com/profile/16672407110077541595noreply@blogger.comBlogger7125tag:blogger.com,1999:blog-8081751738815878503.post-78854399149246796602016-11-01T17:35:34.486-04:002016-11-01T17:35:34.486-04:00Thank you, excellent explanation!Thank you, excellent explanation!Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8081751738815878503.post-41915286925184246372016-06-29T13:52:26.391-04:002016-06-29T13:52:26.391-04:00His reply was basically a copy and paste from what...His reply was basically a copy and paste from what biobrewer/theyeastbay said on beer advocate.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8081751738815878503.post-29537685497307186212016-03-28T14:22:30.887-04:002016-03-28T14:22:30.887-04:00Boiling does negatively effect the efficacy of gel...Boiling does negatively effect the efficacy of gelatin, for the simplest of reasons. Above ~77C you denature the gelatin fragments sufficiently enough to completely denature the hydrophobic regions. These will then promote rapid gelatin aggregation once the solution begins to cool - this is the major mechanism by which gelatin forms into a gel (i.e. jello). But in beer this leads to the formation of gelatin blobs, which greatly reduces the surface area of gelatin available for adsorption of haze materials.<br /><br />Solubilized gelatin (i.e. heated to 70-77C) retains enough structure to limit aggregation while still exposing some of the poly-hydrophobic motifs of the collagen peptides. Because it remains soluble, it has a huge surface area compared to over-heated (and thus aggregated) gelatin, as the resulting beer-gelatin solution is a suspension of single gelatin molecules & minute gelatin aggregates. This gives you an absorptive area much, much larger than gelatin which has aggregated.<br /><br />Like most colloidal clearing agents, gelatin is amphipathic and functions by aggregating materials through a combination of hydrophobic and electrostatic interactions. Whether the electrostatic or hydrophobic elements dominate a clearing reaction depends on the target molecules; for carbohydrates its the electrostatics; for proteins (which is the bulk of haze) hydrophobicity is primarily responsible for clearance. You can use gelatin to precipitate proteins under conditions which otherwise eliminate electrostatic interactions (e.g. low or high pH, high salinity), with little loss in efficacy compared to conditions where electrostatic interactions occur.<br /><br />Moreover, most gelatins in grocery stores are type b gelatins, prepared by hydrolysis by acid and base, not by acid alone (acid hydrolysis limits the collagen sources used to prepare gelatin; base hydrolysis allows nearly any collagen-containing item to be converted into gelatin). B-type gelatin has a pI of 4.7-5.2; right in the pH range of beer. Or, in other words, gelatin in beer is largely unchanged. Type A (acid-only) gelatin has a much high pI and thus would be charged in beer; however, type A is somewhat of a specialty item as it tends to be more expensive and not overly useful as a food thickener/gel agent as it undergoes less crosslinking during cooling.Bryanhttps://www.blogger.com/profile/16672407110077541595noreply@blogger.comtag:blogger.com,1999:blog-8081751738815878503.post-31529579338262205842016-03-28T13:53:30.990-04:002016-03-28T13:53:30.990-04:00You claim that gelatin will gel in the beer too mu...You claim that gelatin will gel in the beer too much if you heat beyond 77C. Isn't this a myth?<br /><br />First of all, it actually says “Boil to dissolve” on LD Carlson Gelatin. <br /><br />I believe this is due in large part to two things:<br /><br />1) Gelatin is simply hydrolyzed collagen, and is often produced by boiling source material rich in collagen in a mild acid to encourage hydrolysis. Boiling is an actual step that speeds up hydrolysis that many manufacturers use in the production of gelatin.<br /><br />2) Collagen, and therefore gelatin, is a protein/peptide based material. So, while boiling (or even heating to 180 F) would affect the structure, the structure is not what results in the clearing effect seen with the use of gelatin as a fining agent. It is the charge of the gelatin molecule The approximate amino acid composition of gelatin is: glycine 21%, proline 12%, hydroxyproline 12%, glutamic acid 10%, alanine 9%, arginine 8%, aspartic acid 6%, lysine 4%, serine 4%, leucine 3%, valine 2%, phenylalanine 2%, threonine 2%, isoleucine 1%, hydroxylysine 1%, methionine and histidine <1% and tyrosine <0.5%.<br /><br />The clearing effect of gelatin arises due to the fact that, at the pH of beer, the collagen is highly positively charged, allowing it to bind to negatively charged molecules/free proteins/cell surface proteins. The positive charge arises NOT because of structure, but because:<br /><br />the pH is slightly higher than the pKa of carboxylic acid side chains on aspartic acid and glutamic acid, making them negatively charged, but only slightly so, as the pH of beer is only slightly higher than the pKa of these acid sidechains.<br />the pH is significantly lower than the pKa of primary and secondary amines sidechains on proline, hydroxyproline, arginine, lysine, and hydroxylysine, making them very positively charged. The positive charge resulting from these residues is not only enough to offset the small amount of negative charge on the glutamic and aspartic acids, but it is sufficiently high enough to give a large positive charge to the overall gelatin molecules.<br />The remainder of the amino acids in the structure have primarily hydrophobic side chains, and do not result in contribution to charge.Jonhttp://jonkel.orgnoreply@blogger.comtag:blogger.com,1999:blog-8081751738815878503.post-70570738386032633852014-09-22T08:14:19.800-04:002014-09-22T08:14:19.800-04:00There is a slight typo above; you need a half pack...There is a slight typo above; you need a half packet to clear 5 imperial gallons (23L, ~6 US gal) of beer.Bryanhttps://www.blogger.com/profile/16672407110077541595noreply@blogger.comtag:blogger.com,1999:blog-8081751738815878503.post-82715612682842394452014-09-20T10:37:55.332-04:002014-09-20T10:37:55.332-04:00Thanks for the article. How much beer are you clea...Thanks for the article. How much beer are you clearing with this 1 packet (1 tablespoon) of unflavoured gelatin? It's the only missing piece of the puzzle. It's likely 5 gallons but figured I'd ask/confirm.<br /><br />Kal<br />TheElectricBrewery.comAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-8081751738815878503.post-73813845659598607672013-06-24T21:37:31.093-04:002013-06-24T21:37:31.093-04:00Great explanation of how to use gelatin and why it...Great explanation of how to use gelatin and why it works. Anonymousnoreply@blogger.com