Limoncello Distillation

[Mad Scientist]

I'm making limoncello and having trouble proofing with a hydrometer. After distillation to remove the sugar and adding water to bring to volume in the volumetric flask the distillate is very cloudy. There are lemon oils visible in the volumetric. Does anyone know if these oils will interfere with the hydrometer reading. We can't get the TTB on the phone so I thought someone here would know.

[InsuranceMan]

Don,

Shoot me a PM and I will get you some info. I have quite a few clients who specialize in this and I will see if I can put you in direct contact with a few of them.

[HedgeBird]

A search for 'obscuration' should bring up a few thread discussing this process, but I don't recall ever seeing anyone ask about oils affecting the hydrometer reading before.

After distillation to remove the sugar and adding water to bring to volume in the volumetric flask the distillate is very cloudy.

We use a lot of citrus/lemon in our gin and typically it also starts out cloudy because there is too much oil. Typically we have been able to "water down" the distillate with pure vodka until it clears up. In one batch we "watered it down" with 7 parts clean vodka to 1 part botanical distillate. This removed all the cloudiness and surprisingly there was little to no loss of the botanical flavor. All this was to say I can't answer your questions, but you might be able to use a lot less citrus for the same result and then not encounter this issue at all..

[mcsology]

The way I've always done it is to blend a sample of your finished product using weighted averages to get as close to your target as possible, while taking extremely detailed notes on details of your blending process. Then, send that sample to a lab that does .001% accuracy ABV testing. Note the variance from your weighted average blend, and then back add water/spirit/syrup to hit your target on the nose with the weighted average method. Then you could use the info on how much you had to add to the batch to adjust to target as an 'adjustment percentage' for future blending without sending to lab. If you want to be extra neurotic about it, you could then lab your adjusted batch to see if you were dead on. Making sure that your blending stocks (spirit, water, sugar syrups, etc...) are all the same temperature will increase accuracy with weighted average blending of complex liquids.

Unless you have a pretty legit lab setup, i'd be worried about incorrect data from non-laboratory-environment ebulliometry.

If you're small scale this method should get you as close as possible without spending dough on unnecessary testing. If you are making big batches of the stuff, it might be best to send every batch to lab and adjust as necessary if you want to be within acceptable % ABV variance.

Also, if you're worried about cloudiness it might be worth considering that citrus oils are pretty volatile and that by doing a 'demisting test' on your 'heads' coming out of the run you can pretty much exclude most of the oil that ends up clouding the batch. I do this on my gin and after about 1% of the run is collected the oils drop below the threshold that causes cloudiness at bottle proof. I just throw the oil-bearing 'heads' back into subsequent batches of macerate. I imagine that it would work about as well with your method for limoncello.