Grapefruit zest flavour not scaling from bench still to production still

[needmorstuff]

I have a 5l bench still, I used 1.5kg of grapefruit per 1l of NGS. Just the zest and the flesh of the fruit. I got a very good extract and the grapefruit oils came over immediately and for the entire run. It's a pot with a 2" riser heated on a heat plate.

I scaled that up and used 57kg of grapefruit for 35l of NGS, again the zest and the flesh. The still is a 100l kettle with internal elements.

I am getting hardly any oils coming over.

I have tried increasing power, reducing column diameter from 4" to 3", then reducing column height all with varying levels of power and still hardly anything.

It is currently running in pure pot still mode, no column to speak of, 2" take off, 3kw power, 100l kettle type still.

I am hopeful that during the 6 hour run that the citrus will come through but it's a bit worrying considering how it came through on my bench still from the start to the end. Also concerning as i thought the citrus came of mostly at the start of a long run as the oils are lighter.

thoughts?

[JustAndy]

Is the lab still glass and the other copper? Grapefruit aroma is sulfur based, which copper can reduce.

[needmorstuff]

Bench still is copper, production still was ran with just SS, no copper

[needmorstuff]

update.

What i failed to mention is i had my other gin botanicals in the boiler. 

Normally i run nice n slow, about 9" per second vapour speed, even then when I usually have to rest it for a period after proofing, to allow some of the earthier notes to dissipate, all fairly standard practice.

I think what I did with this run is use too much power, trying to get the grapefruit bouquet that was so prevalent on my bench still - this amplified those earthy notes that are so pungent and this masked the grapefruit almost completely.

I discovered this as I placed the distillate back into the boiler after the cleanup, proofed back to 30% (60 proof) - it immediately clouded up like milk showing the high concentration of citrus oil. I ran it again, nice n slow like normal... BAM - grapefruit straight off the bat.

Did the full run with a cut at the start and turned off boiler at my normal switch off and it's got the grapefruit all right.

Strange how the other botanical oils masked the grapefruit so effectively.. you live n learn.