I've never really given much thought to attenuation until I was planning my current beer and was planning for some hop creep. That, combined with a brut IPA I brewed last fall got me thinking about yeast and the published attenuation ranges for them.
I've always just sort of envisioned it as a matter of they somehow could only eat say 75% of the sugars (+/- some amount). The reality, I think, is much different.
Let me start with my rudimentary "I don't want to think chemistry" perspective on mashing, sugars and yeast. My understanding is that the malted grains contain complex sugars that are, in general, very hard for the yeast to consume. I think of yeast as snakes and the sugars are simply too big for them to swallow.
Enzymes in the mash do one of two tasks. One enzyme chops the big sugars in half, leaving them still hard to digest, but marginally edible. The other lops one chunk of of each end and those chunks are really easy for the hungry little yeasties to munch on. Those two enzymes work best at different temps (with some overlap). When combined, the one that chops in half leaves more ends for the one that chops off the ends, resulting in a more fermentable wort.
So, when we talk about the average attenuation of the yeast, it's not that one eats 75% and gets full and another can eat 80%. It's that one is, perhaps, slightly better at eating those larger chunks than the other such that they both eat all the simple sugars and one eats more of the varyingly more complex sugars than the other. This would explain then how adding enzymes can get much higher attenuation than the published numbers for a given yeast. It would also explain hop creep, where the hops have enzymes that break down more of the bigger sugars allowing the yeast to have desert.
Do I have this about right or am I missing something? Anything to add or correct?
I just sort of had this revelation today and wanted to see if I have it about right (though very simplistically).
I've always just sort of envisioned it as a matter of they somehow could only eat say 75% of the sugars (+/- some amount). The reality, I think, is much different.
Let me start with my rudimentary "I don't want to think chemistry" perspective on mashing, sugars and yeast. My understanding is that the malted grains contain complex sugars that are, in general, very hard for the yeast to consume. I think of yeast as snakes and the sugars are simply too big for them to swallow.
Enzymes in the mash do one of two tasks. One enzyme chops the big sugars in half, leaving them still hard to digest, but marginally edible. The other lops one chunk of of each end and those chunks are really easy for the hungry little yeasties to munch on. Those two enzymes work best at different temps (with some overlap). When combined, the one that chops in half leaves more ends for the one that chops off the ends, resulting in a more fermentable wort.
So, when we talk about the average attenuation of the yeast, it's not that one eats 75% and gets full and another can eat 80%. It's that one is, perhaps, slightly better at eating those larger chunks than the other such that they both eat all the simple sugars and one eats more of the varyingly more complex sugars than the other. This would explain then how adding enzymes can get much higher attenuation than the published numbers for a given yeast. It would also explain hop creep, where the hops have enzymes that break down more of the bigger sugars allowing the yeast to have desert.
Do I have this about right or am I missing something? Anything to add or correct?
I just sort of had this revelation today and wanted to see if I have it about right (though very simplistically).
