Floating layer in bottling tank

[Gus]

Hi all,

Once we have proofed our gin down to 40% abv and let it rest for a few days, we get a white layer that floats on the top of the tank as per the attached image. This layer gets more defined over time.

We can skim it off, but we don't get all of it as when disturbed it turns into fine wisps.

Does anyone know what this is, or has anyone else seen this before?

Cheers,

GusNZ

[Foreshot]

Please describe your process for proofing (one shot or slow proofing), from what ABV, what product it is (gin, rum, etc), does it have an abnormal flavor, what cleaning protocol/products do you use for the tank? That will help us figure it out. 

From the details you provided you might be getting phase separation of esters/fatty acids or saponification, but that's WAY more than I've ever seen. Anytime you go from above ~45% ABV to below that's always a possibility.  That's a lot of stuff so if you use PBW or another detergent maybe it did not get rinsed out properly? 

[Gus]

Our process for proofing is:
Day 1 - run the macerated gin through the still, comes off at ~83.2% for the run
Day 2 - Proof to 45% abv
Day 4 - Proof to 42.5% abv
Day 6 - Proof to 40% abv

Our gin is always louchy in the tank when dropping below ~44% abv, but we rest for 4+ weeks which with warmer summer temperatures allows the gin to clear up and in winter it remains cloudy and simply clears up when filtering through our 5micron enolmaster filters. We run 32.2g/l and 34.7g/l botanical loadings in our gins too, which are macerated at 50% abv, then diluted to 40% for running through the still.

Apart from the first thorough clean when brand new, we have never cleaned these tanks (~2yrs since new) as these tanks only ever hold gin.

 

[Golden Beaver Distillery]

You using RO water, spring or tap water?

[Gus]

In that photo it was tap water, and we now use carbon filtered water but we still have the same thing happening. 

Water test results attached

[Gus]

On 8/16/2022 at 7:50 AM, Foreshot said:

Please describe your process for proofing (one shot or slow proofing), from what ABV, what product it is (gin, rum, etc), does it have an abnormal flavor, what cleaning protocol/products do you use for the tank? That will help us figure it out. 

From the details you provided you might be getting phase separation of esters/fatty acids or saponification, but that's WAY more than I've ever seen. Anytime you go from above ~45% ABV to below that's always a possibility.  That's a lot of stuff so if you use PBW or another detergent maybe it did not get rinsed out properly? 

I've been doing a lot of research on phase separation based on your post @Foreshot, so thank you very much for your pointers. I've got some trials planned for todays gin run based on what I've read so I'll let you know how things go.

[Gus]

So still trying to figure this out, but I suspect it's coming over in the heads then separating out with resting.

Has anyone else experienced anything similar to this?

Cheers, Gus

[Kindred Spirits]

Can you filter it out with a fine, pleated filter? If so, you might just need to switch to a .5 or 1 micron filter.

[jocko]

What is your base spirit?  NGS?

[Gus]

2 hours ago, jocko said:

What is your base spirit?  NGS?

Neutral cane spirit, 96.4% abv.

5 hours ago, Kindred Spirits said:

Can you filter it out with a fine, pleated filter? If so, you might just need to switch to a .5 or 1 micron filter.

Yes it is removed with 5 micron filters currently, but it would be nice not to produce it in the first place.

[Gus]

Here is a photo of todays batch for bottling, with the same floating layer on top but not quite as significant.

The 5 micron filters do remove it, but over time I assume they will saturate. 

My guess is still that it's coming over early in the run based on what demisting tests are showing, but still trying to figure out exactly what it is and how to stop it from happening in the first place.