Extract Winterization: Background and Basics

An Overview of Winterization and Dewaxing for Botanical Processors

Extract Winterization: Background and Basics
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What is "Winterization"

Winterization, also commonly called “dewaxing,” is a refining process that removes undesirable plant waxes from botanical extract. If these waxes are not removed from the extract, then the final product can exhibit cloudiness, reduced potency, and off flavors. Winterized extracts are said to have longer shelf life than unwinterized extracts.

Winterization in Other Industries

Winterization is a process that is common within the botanical extraction industry as well as in other industries. The edible oil industry, for example, winterizes Canola and other food oils to ensure their shelf stability and clarity. Cloudiness or haze in an edible oil would reduce its consumer appeal and would be damaging to sales. The biodiesel industry winterizes their fuel to ensure that the fuel flows well when it is cold out.

Do I Need to Winterize?

This depends upon the extraction technique and on the final product specifications.

Generally, processors will want to winterize their extract if their product specifications include any of the following:

  • All botanical extracts that are going to be vaporized or inhaled should be winterized. Some plant waxes and saturated fats can create foul flavors or aromas when smoked or vaporized.
  • All extracts that are going to be judged, selected, or priced based partially on their physical appearance should be winterized. Cloudiness / haziness is unappealing to bulk extract buyers and to end consumers and will reduce the value of your product.
  • If you wish to achieve the highest potency of CBD or other active ingredient in your extract, then you will want to winterize. Winterization can increase the potency of an extract by 5-15%.
  • If shelf stability is important for your extract, then you will want to winterize. Winterization tends to extend the shelf life of an extract.
  • If you are performing reverse phase chromatography in a subsequent process, then you will want to winterize your extract thoroughly. Plant waxes adhere to reverse phase chromatography media and shorten the media’s life.

Which Extraction Methods Require Winterization

The extraction technique plays a large role in determining the amount of wax that is present in the unrefined extract. Some extraction techniques produce extracts that are low enough in wax that they are considered “winterized” for most purposes without further refining. Other extraction techniques produce extracts that are super high in wax content, and that cannot be used for any purpose without dewaxing.

Listed below are the common extraction techniques and the generalized characteristics of each extract:

  • Cold Alcohol Extraction: Extracting botanicals in ethanol or methanol at temperatures below 0° F will produce extracts that are very low in wax. Unless you are going to conduct chromatography or unless you have extra stringent product specifications, you generally will not need to conduct a winterization procedure.
  • Cold Butane/Propane Extraction: Extracting botanicals in butane or propane at temperatures below -40° F also generally produces an extract that is very low in wax content. These extracts will generally contain a slightly higher wax content than the alcohol extracts, but still low enough to be considered “winterized” in many cases.
  • Supercritical CO2 Extraction: Supercritical CO2 extracts contain substantial amounts of wax. These extracts will almost always need to be thoroughly winterized before they can be used.
  • Warm or Room Temperature Solvent Extraction: Extracting with ethanol, methanol, isopropanol, heptane, hexane, butane, or propane at temperatures above ambient will create an extract that contains a noticeable amount of wax. These extracts will generally need to be winterized, but there are some exceptions.

How To Winterize

Winterization is a simple process. The basic steps are described briefly below:

  1. An extract that needs to be winterized is dissolved in an alcohol solvent. Ethanol and methanol tend to work the best, but methanol is very toxic and should be handled with care. The extract is typically dissolved in the solvent at a concentration of between 1:3 and 1:10 by mass, depending upon the exact process specifications.
  2. The resulting solvent and extract solution, called miscella, is then chilled. Plant waxes and saturated fats will become insoluble at the lower temperatures and will fall out of solution. These plant waxes and fats appear as a cloudy semi-solid gel in the solution. The temperature that winterization is conducted at depends on the facility and the operator, but generally solutions are cooled to either -20° C, -40° C, or -80° C. The colder the temperature required, the more expensive the chilling equipment.
  3. After the waxes and fats have precipitated, the suspension is passed through a fine particulate filter with pore sizes between 1 micron and 45 micron. The suspended fats and waxes will be caught in the filter, and the cannabinoids and desirable compounds will pass through the filter unimpeded. Fats and waxes tend to blind over filtration equipment, so proper equipment selection and sizing is important.
  4. After the fats and waxes have been separated from the winterized miscella, the solvent must then be removed from the extract. The winterized solution is then transferred into a solvent recovery apparatus, such as a rotary evaporator, or Aptia RX-FFE.

Winterization Equipment

There are several ways to winterize extract. The most common way, and the way that Aptia recommends, requires a winterization reactor, a stainless filter housing, and a solvent recovery apparatus.

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The winterization reactor is a stainless steel jacketed tank that is mixed and that is cooled by an external refrigeration unit. The extract and the solvent are loaded into this vessel and they are mixed together into a solution. Then they are also cooled in this vessel. Aptia manufactures a series of reactors, ranging from 50 Liter / 15 Gallon capacity up to 660 Liter / 175 Gallon capacity, that are designed specifically for this purpose.

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After the solution has been chilled in the reactor, it is sent through a filter housing to separate the waxes from the miscella. Aptia manufactures the DWF stainless filter housing specifically for the moderate scale filtration requirements that are so common in the hemp industry. Aptia can also provide larger equipment for larger filtration requirements.

The winterized miscella then needs to undergo solvent recovery to separate the winterized extract from the solvent. Aptia manufactures many solvent recovery systems to meet each different facility’s requirements.

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