Rotary evaporator. More than just for cocktails.

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Just another equipment post. It seems to me that there is currently a lot of buzz about the rotovap, and for good reason. It does some amazing things, but some terrible things as well. I’ll make sure to touch on as much of both as I can.

First thing, what is it? Essentially its a machine that distills under a vacuum. The vacuum lowers the boiling/evaporation temperature of the liquid, therefore allowing you distill liquids at temperatures as low as 35 degrees Celsius. The rotating flask is there to increase surface area, therefore increasing the rate of evaporation. Pretty easy to understand isn’t it?

First, the coolness factor of the rotovap. You are able to collect 2 liquids from it. One is the percipitate which is the clear liquid, and there’s the concentrate which is in the rotating flask. The percipitate has the aromatics of the original liquid. Aromatics are usually volatile and will usually be carried with the evaporation. From what I’ve experienced, acidity carries over as well. But keep in mind, the percipitate usually does not carry over flavour! Though, some aromatics (like chocolate) does have some taste, like a mild bitterness, but usually no flavour. Distilled apple juice will smell like apple juice but have no taste. And also, since the percipitate only has the aromatic component, the smell seems more intense since there are no other components mixing with it. The concentrate, is simply that, a concentrate of the original liquid; this would be similar to a reduction that’s been boiling for a period of time. The MAIN DIFFERENCE is that in the rotovap, the process is under a much lower temperature, so the flavour will be different; things didn’t get “cooked”. So imagine that flavours that disappear due to the high heat will be preserved.

Here is a photo of the percipitate.

Now for the other part. Sometimes, you think you’re going to get this amazing smelling liquid, but you just end up with water. Sometimes, the water just tastes downright offensive. Certain aromatics that were masked in the original liquid now become apparent in the percipitate. Perhaps those aromatics need to be balanced with the other components in the original liquid to taste good. I suppose the lesson here is that if it ain’t broke, don’t fix it! Though, I can’t help but test that statement once in a while. Well, a lot actually.

With that said, it’s a really interesting piece of equipment. I think bartenders/mixologists would be the ones who will primarily benefit from this. Separating the alcohol from vodkas, bourbons, whiskies, etc can certainly widen the amount of drinks you can make. The concentrate can be mixed with various sugars to be a mind blowing syrup. The high alcohol percipitate can be infused with anything you want, and alcohol absorbs flavour much better than water. As for chefs, the fun here is that you can make something that looks like water, smell like something completely amazing. Also, keep in mind that you can add white sugar, acid powders, and other ingredients that can keep the clarity. Call it a mind game type experience (ie clear chocolate milk).

I hope this post was informative. Oh, one more piece of information, if you want one, start saving up. Total is about $9,000 for all the components. If you want to play around with it, come by the Food Lab.

Things I’ve made with it:

1. Edible tobacco vanilla perfume

2. “Grappa” from crappy white wine. The “grappa” was actually quite delicious

3. Nice bases for syrups made from the concentrates of whiskies, bourbons, etc.

4. Clear chocolate milk (inspired from Alinea)

5. Components for a clear caesar. Or in the US, its bloody mary.

6. Also helps to dry up a wet iPhone.



2 responses to “Rotary evaporator. More than just for cocktails.”

  1. SousVide Dash (@SousVideDash) Avatar

    Try rotovapped habanero some time. None of the heat makes it across into the distillate. Your nose tells you it is going to be blazing hot, but it’s not. When you taste it you just get pure fresh pepper flavor.

    1. torontofoodlab Avatar

      I have in fact tried it. Though I didn’t make it myself. PolyScience had the stuff during the NRA.

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