I made a 5% pale ale a couple weeks ago using 2nd gen Kviek Lutra repitch. It’s been hot as !#$ and I was bored so I stuck the bucket on the back porch and left it sit at 95F after pitching. The tilt showed the gravity dropping within a couple hours. It sat overnight and was back up to 95F the next day. By 3pm, the tilt was showing 1.008 and sat there for another two days. It tasted OK so I kegged it, carb’d and chilled. I was drinking a pretty good beer 5 days after mash in.
I don’t taste or smell any off flavors. How does Kviek ferment so fast and not leave behind “green beer” or diacetyl or other off flavors? Did I just get lucky or can I expect to make 5-day 5% beers this way in the future?
Diacetyl is most commonly caused by alpha-acetolactate, which most beer yeasts produce, but then reabsorb near the end of fermentation. If the alpha-acetolactate is not “cleaned up” after fermentation diacetyl can result. Some strains produce less alpha-acetolactate than others.Some have even been engineered or selected to create almost none.
“Green beer” iscaused by Acetaldehyde which is also generated more or less by most brewing yeasts. Some strains produce less than others. Acetaldehyde usually fades over time, the less that is produced during fermentation, the less of a problem and the shorter the aging time to remove it.
My guess is that kviek doesn’t generate very much alpha-acetolactate or acetaldehyde, or it is very good at cleaning it up.
I brewed a pseudo lager Festbier using Lutra. Fermenting at 68 and it’s cranking away. I read several places that Kviek/Lutra does not need a diacetyl rest, so going to skip it.