Rotovap

grim

F@ck yeah.

CothermanDistilling

Other than a bit of a problem with the rotary seal leaking a bit, Rotovap is workign pretty well...

Did Ghost Pepper and Carolina Reaper this weekend, noticeable 'oils' left when done...

and did pink peppercorn today and rolled till nearly dry... will compare result with the small heat still..

CothermanDistilling

So I found a scoring on the vapor tube that was causing the slight leak, and ordered a new replacement form Ace Glass... Quality is not what it used to be...

https://www.youtube.com/watch?v=12xab60hixw

TheMechWarrior

I feel your pain mate. I've been burnt numerous times by cheaper Chinese imports. The most annoying thing for me is they do know how to make a great quality product when it's required. I suspect all the cheap items we find are from the reject pile.

CothermanDistilling

So I also got a 2L evaporator flask, because my cheap Chinese one wobbled a bit... the new one form Ace looks beautiful, but the lip on the edge id too small and round to hold the wire safety bail... it nearly fell off the rotovap twice while I was installing it... Switzerland, China or NJ can all make good stuff, just some places are harder to wade through the BS...

N_D

Finally our beauty arrived and she is up and running, still waiting for delivery of 2L & 3L evaporator flask.

Let's get this thread going again!

Is there a reason why you guys like to go from straight neutral a part from geting more product? From first run there was clear that we need to macerate to reach more flavour, do you guys macerate prior every run?

CothermanDistilling

nice rig! I am still in the experimental phase for most products other than Jalapenos, which I macerate and use 170 proof.. (I did 190, 170, 150, and the 170 had the best balance of flavor and aroma to me... a friend actually liked the 150 better, so I may try 160 and 170 side by side..) I macerate and strain off and do liquid when I can.

N_D

Thanks! We narrowed it down to two manufactures and went visiting them for demo run and this setup was miles ahead in quality and functionality, great vacuum controller with different operation programs. We have only played with the automatic function now in the beginning using setpoints.

Have you found any settings with mbar/temp that you think works best? Found great tips on the cooking issues article. We are going to look at a Peristaltic Pump since it had been great to be able to taste during the run. Do you have a product in internal tube to fill the evaporator flask? We missed that, must check if there is one available to this system.

CothermanDistilling

if working with non-volatile flavors, 100mbar 20/40/60 (celsius temps of chiller, vapor, water bath) are good.

with things that 'cooking' ruins flavor, such as cucumber or jalapeno, I go for a bit lower, 20c chiller/,30-35c vapor, and 45c bath temp..

since were are almost always dealing with a 'mix' of solvents (ethanol and water), you will see the vapor temp rise through the run.. if you can program yours to ramp or do a gradient, that will probably be best...

I have not done the internal fill tube yet, I got the internal tube that goes through the vapor tube into the flask a few months ago, and just got the external tube to suck out of a container from amazon yesterday... hopefully will try this week..

also, the rotary seal seems to be a bit finicky, order some spares...

grim

I wish there was some easier way to clean the condenser, one that didn't include always praying before the procedure.

grim

I think colder is better, the whole point of vacuum distilling is to eliminate the potential for thermal degradation - lower boiling point. Colder the chiller you got, the deeper vacuum you can pull, and lower the boiling point you get. Flirt with the bleeding edge where bumping goes bad when you just look at it the wrong way.

We use a VWR chiller, it runs at a set point of -25c. We use an insulated Igloo beverage jug as a chiller glycol reservoir, and it takes a little while to pull down so cold. Fun to watch the poly lines ice up when it's really humid. The condensation is annoying though, I really need to find small diameter (3/8") tubing insulation.

We've got the dry ice condenser too, for when we want to be really silly.

grim

Think I need to switch my pump, 50% glycol at the chiller set temp is like syrup.

N_D

Great inputs from both of you!

We also think that one big reason of the investment is thermal degradation with respect for botanicals volatile for heat. Other fact that the system gives us a great mini lab fooling around with recipe development is also a great. We are running it straight from water-pipe in the beginning since we have almost constant 10 degrees Celsius water at no cost. Were we are now 10 degrees Celsius if good enough, but we will probably get a chiller in the future when we’re more experienced.

Do you have any picture on your setup @Grim ?

CothermanDistilling

I rinse my condenser from the top, the bottom, and the vapor tube with 190 proof then distilled water using the nalgene bottles you can see in the pictures of my setup. I just squirt it in and try to hit everything...

My glycol is just propylene glycol and water, guessing 50-50, I have a few drums I got from a recycler friend.. very thin, chiller has a sticker saying to not use Syltherm 800 Silicone Heat Transfer Fluid Product Information (PDF)

N_D

When you guys say that you macerate and use neutral, do you really macerate in neutral or strain off and blend with neutral?

CothermanDistilling

macerate in neutral.. mainly for the sanitary/preserving qualities of ethanol, but also because it distills off a LOT easier in a rotovap than water..

N_D

Interesting, we have not done a run yet on neutral but definitely buy your point that it will distill a lot easier. Will definitely give it a try, probably limit which botanical you can use, but that's the fun with this - you can play around while doing runs on the bigger still.

Have an idea of try to 'infuse/quick macerate' in a siphon using N2O, have you guys tried that?

One other thing, does your Rotor have a vapor probe or have you modified it? Did not get it when you mentioned 100mbar 20 (celsius temps of chiller) /40 (vapor) /60 water bath...

grim

We do neutral only, but fresh fruits and vegetables have enough water in them to reduce the proof of the collected distillate quite a bit.

I've run with solids in the boiling flask as well. I tried a few runs where I put the maceration through a bullet blender and basically disintegrated everything prior to distilling.

If you are using a really big flask, and trying to maximize run yield, you start to run into flask weight limitations - and solids become a waste of space, and a pain in the ass to clean.

grim

The 20/40/60 is just a rough rule of thumb.

You adjust your vacuum to hit a vapor temp of 40c:

Buchi 20/40/60 rule for Rotary Evaporators (PDF)

Keep in mind, the minute your pure ethanol gets water in it, as the run progresses, it's going to require a deeper vacuum to maintain 40f, and if you have lots of water, you may need to adjust your vacuum a few times through the run. Keep in mind, a rotovap runs like a pot still.

Or, you can very, very slowly increase your bath temperature. Don't do it quick, impatiently, like I did once.

grim

Pulling 100mb vac on azeotrope ethanol is probably closer to 30c, not that it matters all that much, you can shift the rule however you like.

10/30/50 for example, just maintain the 20c differentials.

My rig does not have the cool vapor temp probe that @CothermanDistilling has. While we have the same rotovap, but I am using older glass.

CothermanDistilling

I have never adjusted my vacuum to hit the vapor temp, I usually just pull as strong as I can without boiling the flask over or having condensation more than 2/3 the way up the condenser...

The glass in the pics with V850 controller has the vapor temp probe come in from behind, you can see it to the left of the green power switch. The V855 that I hope to run soon has an additional temp probe that comes in from the top and has multiple sensors on it to tell the gradient in the column for automatic distillation..

kimbodious

This is a rotovap still being commissioned at a new local distillery.

grim

Here's my little rig. Buchi R-215, J-Kem DVR 280 Vacuum Controller, Vacuubrand MD-1C 3 stage teflon diaphragm pump.

CothermanDistilling

R-215 with V-855(with $500 sensor wire) AND buchi glass for $2k... this is a very good deal

Buchi Rotavapor R-215 Rotary Evaporator System + V-855 Vacuum Controller + Tubes @ eBay

Joemcdo

@kimbodious said: This is a rotovap still being commissioned at a new local distillery.

Who is building/ designed this still for you? It looks beautiful!

kimbodious

@Joemcdo said: Who is building/ designed this still for you? It looks beautiful!

Not my still but it is a local business. The guy in the picture adapted the design which is built from components sourced from China.

jbierling

Old thread I know, but I'm curious if anyone has tried vacuum distillation (with a rotovap perhaps) on a barrel aged [whiskey] product. Is it any different than distilling at atmospheric pressure? Anything from the barrel lost by the high temp?

Bolverk

I remember reading something on BA where Stephen rotovap'ed some aged spirit and added what was left to an unaged spirit and if I recall it made that unaged taste just like it was aged for the same number of years.

grim

We de-alc finished spirits and wines with the rotovap all the time.

Did a few bottles of bourbon for "dry January" for friends. Not necessarily zero alc, as you need to distill off a 'heads' fraction first, and add that back in after removing the bulk of the ethanol.

You absolutely can not do this at atmospheric, the higher temperature will absolutely destroy numerous flavor compounds, you need to do this under deep vacuum at very low temperatures, and have a chiller that can support the temp ranges you need (we run around -10c or -20c depending on the time of year).

When doing these kinds of temp sensitive evaporations, we run the water bath at a few degrees over ambient so we have some way to control heat input.

grim

Adding "heads" back in to make the finished de-alcoholized product is absolutely critical for the aromatics and lighter flavors, otherwise the finished product is flat/bland. This product absolutely needs to be kept very cold, and is not stable for more than a few weeks. The esters will disassociate back into acids as the reduced alcohol content throws off the equilibrium.

Have played around with concentrating the flavor of bourbon as well with this. Where we take a bottle, extract the heads portion, and then remove all the water and alcohol to form a thicker concentrate, and add both of these back to an unaltered bottle (less a little volume).

It's interesting, but more isn't always better, lots of these were bitter oak bombs. It's kind of like breaking off a piece of the "sap" off a leaky large barrel and tasting it.

I've never tried fractionally distilling an entire bottle. Breaking vacuum with every fraction is very time intensive, would probably take me half a day of babysitting to break 750ml into 15 50ml fractions. I know they make a 'cow' for the Buchi, but I've never seen one come up for sale on eBay.