Common Applications of Wiped Film Stills: Citrus Oils

For the next application, let’s talk about Citrus Oils.

Citrus oils are primarily obtained by cold pressing the peels of a citrus fruit to extract release the essential oil.  Cold pressing is done to avoid damaging the valuable compounds in the peel by exposing them to high heat of methods like steam distillation.

After pressing, the oil is refined further by centrifuging and filtration and at this point is a complete essential oil and can be used as is.

However, a lot of processors then proceed to distillation to separate the oil into various components.  The oils typically consist of mono-terpenes (predominately D-limonene), sesquiterpenes, and various waxy compounds. 

A process known as “folding” is often done to distill the D-limonene away from the rest of the compounds.  The D-limonene is often used as an industrial cleaning agent, solvent, insecticide, and cosmetic.  Then the sesquiterpenes are distilled away from the waxes to be used in the flavor and fragrance industry.   Finally, the residual tars are often distilled further to target high value compounds like nootkatone and sinensal.  All of these distillations are performed on wiped film stills. 

Many times, the initial folding is performed on traditional fractional stills, because the monoterpenes can be removed gently with a minimal of damage to the sensitive flavor compounds.  However, performing the subsequent distillations on wiped film stills is often preferred.  Wiped film distillation is gentler than fractional distillation due to the minimal heat exposure.  Traditional stills cook on the material for hours or days, while wiped film stills only see the feed material for seconds to minutes.  Therefore, wiped film stills avoid creating burnt notes, and can produce higher value flavors.

However, wiped film stills do have limitations.  They are simple distillation systems and don’t have the fractionating ability of the traditional stills.  Therefore, they are often used in tandem with traditional stills, and their use needs careful planning and research. 

If you have questions about your exact citrus application, please reach out to learn more.