Lette litt etter en god bekreftelse på dette med det konstante forholdet mellom de to vdk'ene:
"(VDKs) are a group of flavor components in beer, most notably 2,3-butanedione (generally referred to as diacetyl) and 2,3-pentanedione. Sweet butter, caramel, or butterscotch flavors and aromas are characteristics of diacetyl, while pentanedione contributes more honey-like notes to beer. See
diacetyl. Both compounds are derived from two ketone groups on adjacent (vicinal) carbon atoms. See
ketones.
They are formed during beer fermentation in consistent proportions, and derivation in this ratio can indicate possible bacterial contamination." (
https://beerandbrewing.com/dictionary/OFH8CHBicP/vicinal-diketones/)
Hvilken gjær bruker du, forresten? Noen produserer mer enn andre, og særlig notorisk er visst wyeast2308/wlp838 (begge fra Weihenstephan 308). w-34/70 er i den andre enden.
Her er noe interessant, også:
"Pentanedione on its own has a sweet honey-perfume smell and diacetyl resembles butter or butterscotch. Of the two, diacetyl is more significant because it has a taste threshold 10 times lower than its partner does, and most yeast strains make more diacetyl than pentanedione. If the pentanedione fraction overpowers the diacetyl fraction I strongly suspect bacterial contamination.
Pentanedione is very similar to diacetyl but only one-tenth as much is found in beer. For most people the flavour threshold for diacetyl is about 0.15mg/L and 0.90mg/L for pentandione."
http://draymans.com/the-role-of-diacetyl-in-beer/