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Andy: There are two types of finings, there's auxiliary finings
and there are isinglass finings.
Isinglass finings are basically the main fining that will clear the beer
the auxiliary finings are something we add to the tank
and they will help the clarifying process
they won't clarify the beer on their own,
but they will just help to make it more clear when we do add the isinglass
The isinglass are essentially swim bladders from sturgeon
It's a fish product if you like
Rik: Fish guts!
Yeah, we usually don't like to advertise that fact!
Rik: Presumably that's not left in the beer when you're drinking it?
No, because what it does is drop the yeast out
So at the moment, we add the finings to the cask
the finings will cause the particles of yeast to come together
and form larger flocculations, if you like
Rik: so that's to do with charges?
That's to do with charges, yes
the auxiliary is negatively charged and I think the isinglass is positively charged
Rik: Either way they're oppositely charged causing them to stick together
They're oppositely charged, yes
Rik: And that then pulls down the sediment?
That will pull down the yeast yes
so it will cause the yeast to come together,
So the yeast will clump together and form larger flocs
and in doing so it will then be able to drop out.
Rik: It'll be denser and sink.
exactly, so if I give this a shake
You'll see the yeast coming from the bottom
and going back into suspension
So you can see there's some reasonably large flocs there
Now they're only there because
this has already been fined and settled for a little while
If we take this one for example
you can see this hasn't cleared yet
It will probably take another 3 hours for this one to clear
So the yeast is still forming larger flocculations and then dropping down
So, really it's a process of
the yeast coming together and getting larger
and you can see the larger bits
are already starting to fall down
by process of gravity, to the bottom of the finings bottle.
Rik: And this is done partly because people want a clear beer?
Exactly, yes
Rik: And also the yeast does affect the taste I imagine?
The yeast does affect the taste but largely this is because
people want beer that's clear
they drink with their eyes as well.