What is a fixative? How do we use them?

[Single Malt Yinzer]

Fixatives are used in Gin, Amaro, Absinthe and other flavored spirits. What are they? Fixatives reduce the volatility of other ingredients so that their aromas last longer. For spirits the most common fixatives are Angelica and Orris root. Others include grains of paradise and cubeb pepper.


https://distilling.com/distillermagazine/the-fixative-effect/
https://gin-mag.com/2018/07/20/the-botanicals-2/
Youtube: The Effect of Different Botanical Fixatives, Dr Anne Brock, Bermondsey Distilery


Non-Beverage fixative links. Good for reference. DO NOT use any of these fixatives unless you know they are food safe.
https://en.wikipedia.org/wiki/Fixative_(perfumery)
https://www.bmvfragrances.com/productcategory/fixative

[contrahead]

Good links. The BMV Fragrances > Products link has lots of information.

[Evil Wizard]

The way I understand it, fixation in distillation has to do with antioxidation. I feel that these herbs or rather their essential oils in the distillate are able to scavenge the oxygen from the water added when proofing and the oxygen that gets into the bottle and dissolves into the liquid.

In the same vein, CO2 is used to purge oxygen from beer cans before bottling.

Gins and Absinthes made without these fixatives will age over time and the plant flavours get woody and spicy in a way I recognize from the difference between fresh cucumber juice and 2 month old cucumber juice (in alcohol). This aging is very noticeable in absinthe due to the herbs added post distillation for coloring and was very prominent in a batches I diluted to 40% and below.

When I was making a vegan cream liqueur with nut protein, the proteins would turn rancid over time (wet cardboard taste) without the presence of Vitamin E and ascorbic acid to scavenge the oxygen. This is common food practice and not hard to understand.

Well, there is plenty of protein in plant material, certainly there is some attached to the chlorophyll that colors absinthe green. But is there any protein in gin post distillation? I seriously doubt it. But there are oils both coarse and essential. Do oils go rancid? Sure they do, and that's usually an oxidization (and heat) reaction.

"essential oils are known to be susceptible to conversion and degradation reactions. Oxidative and polymerization processes may result in a loss of quality and pharmacological properties." https://onlinelibrary.wiley.com/doi/ful ... 4337.12006

The idea that fixatives reduce volatility sounds like a holdover from perfume making, one of my old hobbies. Reducing volatility would give the perfume a long period of action. They would also use something like ambergris to INCREASE volatility.
Here's the thing, if those fixatives decreased volatility wouldn't we notice it during distillation by a small change in temperature required to distill the liquid? Some scientist would have noticed by now.

Anecdotally, the first time I made 1000L of absinthe and I was grinding up the herbs, I got a whiff of Angelica dust that put me on my ass. It was like getting a face-full of CO2. I'm pretty sure it scavenged all the oxygen out of my lungs.

Are Angelica and Orris known antioxidants? Sure they are - google it.

source: 15 year pro distiller specializing in herbs.

[Single Malt Yinzer]

I think it's two separate chemical processes. Fixation is about reducing volatility so that the botanicals aren't lost to evaporation. Oxidation, in this context, is about maintaining the flavor quality of the botanicals.