Biotransformation? Hops? Schedule?

[Dirty Dingo Brewing CO.]

Scott Janish says that ale yeast in general can biotransform

"You can see from the two charts below the biotransformation by the ale yeast (S. cerevisiae). Although its cutoff in the charts, the bottom line represents time (days) during fermentation. It’s amazing to see geraniol basically disappear during fermentation and transform into citronellol!"

With lallemands NEIPA yeast, I would say that like verdant, the yeast itself is attributing to most of the flavour

 

[GFHomebrew]

Scott Janish says that ale yeast in general can biotransform

"You can see from the two charts below the biotransformation by the ale yeast (S. cerevisiae). Although its cutoff in the charts, the bottom line represents time (days) during fermentation. It’s amazing to see geraniol basically disappear during fermentation and transform into citronellol!"

With lallemands NEIPA yeast, I would say that like verdant, the yeast itself is attributing to most of the flavour

Remember yeast manufacturers would have to back up their statement if putting it (Biotransformation) on the label.

Alot more I'd comming out way with this.

I've been wondering if adding additional fruits to the fermentor and what affect Biotransformation has on ther flavour compounds eg turning one flavour compounds into another.

I've got a crap ton of passionfruit on the vine ATM I'd love to give this a whirl again in a tropical hop forward Blonde ale.

 

[Brewer #335694]

I don’t understand the science behind it. But I dry hop on the 2nd or third day after fermentation starts. Versus waiting until it was almost completely done (or done) which I used to do. I experienced a big difference in flavor doing it earlier and I still get a fair bit of hop aroma (it’s not “scrubbed” out). So I am a believer in the bio-transformation trend.

There's a fair bit of evidence coming out that the original biotransformation that people targeted, i.e. hop oils transformed from one type to another during active fermentation (e.g. geraniol to citranellol), may not make much of a sensory difference. So while it happens, it may not be worth the effort depending on your process. I still do it, but I've really scaled it down and for me it's more about oxidation control than biotransformation.

There's still a few other biotransformations that are being chased by people looking for bigger and different hop flavours. Some of them are hardly even related to fermentation. Thiol release is probably the trendiest at the moment and people are examining process changes focused on mash hopping (with Saaz would you believe?), reducing whirlpool additions and using later and shorter dry hops to maximise the chances of releasing the thiols with the tropical fruit flavours.

Everything is changing every few months in this space, so who knows where the process changes to encourage/discourage different types of biotransformation will settle down? Actually, with the complexity of organic chemistry it's sure to take ages, if it ever does.

On the idea of which hops to use and when and not really related to biotransformation, Yakima Chief have released a great PDF showing the typical compounds in their hops. It then shows how likely these compounds are to survive the various stages in a brew day. So if one compound has got zero chance of surviving the boil, they suggest using hops with a lot of that compound in the dry hop. But if a hop has a fair bit of a compound that survives the boil, think of adding that at ten minutes or flameout. So Azacca should only be used in late dry hop, but Citra is good late in the boil or the active fermentation dry hop.

It also talks about matching hops with different compound profiles. So don't blend two hops with high concentrations of the same compound, look to find two hops with different concentrations. So for their hops, don't blend Loral and Talus, they're too similar. Try Loral and Crystal instead.

To me it's a really helpful document. Just wish we had the profiles for a few of the other hop companies - https://cryopopblend.com/wp-content/uploads/2021/10/Survivable-Compounds-Handbook.pdf

Some resources if you want to dig into these things more:

• https://byo.com/article/biotransformation/ - interesting summary on different types of biotransformation
• https://www.masterbrewerspodcast.com/231 - a review of the sensory impact of different types of biotransformation
• http://scottjanish.com/the-locksmit...hops-and-phantasm-powder-to-thiol-drive-beer/ - Scott Janish going to ridiculous lengths to free thiols
• There's also a few on the bru lab podcast (https://brulosophy.com/podcasts/the-bru-lab/), some not so biotransformation focused, but things like episode 35 and 44 are interesting and in this space.