Har sakset lid fra en tekst What to do about it: You're not going to believe how simple this is. Do a diacetyl rest; that is, leave your beer in the fermenter for two or three days after it looks like the fermentation is complete. That's it. That will give the yeast time to clean up the diacetyl they've produced. If you're brewing an ale, the fermentation temperature is already high enough that the cleanup will proceed rather quickly. If you're brewing a lager, try this trick: start allowing the fermentation temperature to rise once the beer has fermented to half its original gravity. By that point, you're far enough into the fermentation that the yeast aren't going to generate any more ale characters (such as fruity esters) and you've still got enough time to let the temperature rise to a useful level, say, 65°F. Maintain this temperature until the diacetyl is gone or until the end of fermentation, whichever is later, then rack for lagering.
How can you tell if the diacetyl rest is complete? There's an easy forcing test that will only cost you a few ounces of beer. Pull a sample from your fermenter and split it into two covered containers. Refrigerate one and heat the other to 140°F for an hour, then taste them both. If they taste the same, you're ready to rack your beer out of the fermenter. If you can taste butter in the heated sample, your yeast is still at work, and you should give it another day or two. Contrary to what the BJCP Style Guidelines might imply, beers without diacetyl taste a lot better than beers with diacetyl. Try this experiment: walk down the popcorn aisle at your local grocery store and take a deep breath. Do you want your beer to taste like that? I didn't think so. And now you know what to do about it. - Richard Stueven for the Green Bay Rackers newsletter April 2003 -----Oprindelig meddelelse----- Fra: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] vegne af Thomas Eibner Sendt: 18. oktober 2005 21:01 Til: [email protected] Emne: Re: [Brygforum] Undergæring og diacetyl Rasmus, On Tue, Oct 18, 2005 at 08:54:02PM +0200, Rasmus Nissen wrote: > Tak for svaret. > Næste gang vil jeg altså tilsætte gæren ved de 20 grader jeg formår at > køle min urt til, tilsætte gæren med det samme og smide det hele i > køleskabet. > > Med hensyn til diacetyl vs. estere: Hvordan smager diacetyl egentligt? > Jeg har selv læst at det skulle give en "butter scotch" smag. Men > hvordan er det lige det smager? Det er ikke alle der kan smage diacetyl. Jeg har selv problemer med det, men er ved at traene mine smagsloeg/mund op til at kunne smage det. Her er et snip fra BJCP's exam study guide: "This compound is responsible for an artificial butter, butterscotch or toffee- like aroma and taste. At low levels, it may also produce a slickness on the palate. A significant number of tasters cannot perceive diacetyl at any concentration, so every judge should be aware of his or her limitations. Diacetyl is a fermentation by-product which is normally absorbed by the yeast and reduced to more innocuous diols. High levels can result from prematurely separating the beer from the yeast or by exposure to oxygen during the fermentation. Low FAN levels or mutation may also inhibit the ability of yeast to reduce diacetyl. Note that high fermentation temperatures promote both the formation and elimination of diacetyl, but the latter is more effective. For that reason, lager breweries often employ a diacetyl rest, which involves holding the beer in the 50-55 F range for a few days after racking to the conditioning tank. Diacetyl is also produced by some strains of lactic acid bacteria, notably Pediococcus damnosus. Low levels of diacetyl are permissible in nearly all ales, particularly those brewed in Scotland, and even some lagers, including Czech pilsners and Vienna-style beers. " Selv er jeg begyndt at laegge maerke til det som en let smoeragtig fornemmelse i min gane. mvh Thomas _______________________________________________ Brygforum mailing list [email protected] http://www.haandbryg.dk/mailman/listinfo/brygforum To get off the list, send a blank mail to [EMAIL PROTECTED] -- No virus found in this incoming message. Checked by AVG Anti-Virus. Version: 7.0.344 / Virus Database: 267.12.3/141 - Release Date: 18-10-2005 -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.344 / Virus Database: 267.12.3/141 - Release Date: 18-10-2005 _______________________________________________ Brygforum mailing list [email protected] http://www.haandbryg.dk/mailman/listinfo/brygforum To get off the list, send a blank mail to [EMAIL PROTECTED]
