Emulsion, Nanoemlusion, Microemulsion, Micelle and Liposome

We believe hemp CBD or cannabinoid-infused beverages or energy drinks, combined with other functional botanical ingredients, represent the future for the struggling hemp cannabinoid industry.

Formulating hydrophobic cannabinoids into beverages is not easy, much more difficult than incorporating them into gummy capsules, tincture, or other solid food forms. Although it is no longer a challenge for the pharmaceutical industry, it still is for the hemp industry especially when cost-effectiveness and clean label formula are at the center of consideration. One may hear of many terms related to cannabinoid-infused beverages, such as emulsion, nanoemulsion, microemulsion, micelle water, liposome, encapsulation, nano powder, water-soluble powder. What do they actually mean? Before diving into the real science behind those terms, let’s enjoy a few fun facts.

1. Nanoemulsion is the drug delivery system for Covid vaccine.

2. It is a fact that micrometer is larger than nanometer, but in the emulsion world, the average droplet size of microemulsion is smaller than that of nanoemulsion (we prefer it be called miniemulsion).

3. Nanoemulsion first appeared in peer-reviewed journals less than 30 years ago (in 1996). The word "nanoemulsion" only showed up in the title, "submicron emulsion” was actually used throughout the context.

4. The average particle size of commercial products labelled as “CBD nano-power” is actually not in the nanometer range. Commonly used spray-drying produces particles with sizes at the scale of low micrometer.

5. CBD or other hydrophobic cannabinoid oils don't dissolve in water. All of these techniques aim to disperse oils in water with desired homogeneity and stability.  Therefore, claims of water-soluble formula are misleading, should more accurately be termed as water-dispersible formula. 

To simplify reading, the multiple emulsion types are summarized in the table below (optimal viewing experience by a computer). Take note that science is not absolute, there is always disagreement on the definitions of those terms even within the scientific community. The definitions used by the majority are cited in this context.

Nanoemulsion is also called lipid nanoparticle, differing it from solid nanoparticle such as SiO2. Because its particle size is still in nanometer range, microemulsion also refers to self-emulsifying nanoemulsion, which we believe to be a better and more precise term.

Thermodynamically stable means the emulsion will be stable forever or until the product goes bad, while kinetically stable indicates a linear relationship between partial size and stability: the smaller the particle size, the more stable the system.

Although disagreement exists, we consider microemulsion and micelle are similar systems. Simply put, microemulsion is swollen micelle. As outlined above, microemulsion delivers the best bioavailability and fast adsorption, but its disadvantages related to dilution sensitivity and high surfactant usage (potential toxicity) greatly limit its commercial use in food and beverage industry.

Liposomes are often categorized to encapsulation technique too. Encapsulation is a more complex subject. The simplistic description of encapsulation is that CBD capsule is encapsulation. The most popular encapsulation technique used in the food industry is microencapsulation, because preferred particle size is in micrometer range. Originating from protecting sensitive compounds, microencapsulation can help water-insoluble compounds disperse in beverage homogeneously if the encapsulant (coating material) is hydrophilic. Commercially available water-dispersible (soluble) CBD powder or so-called nano-powder belongs to microencapsulation. The stability of dispersion relies on the properties of encapsulant, based on our evaluation, most water-dispersible or nano CBD powder is not stable enough for shelf-stable beverages. Because the list of encapsulants is much longer than that of emulsifiers, and the stability is affected by too many factors and competing with water dispersibility (hard to get both), we don’t recommend microencapsulation as the technology of choice for cannabinoid-infused beverages for cost-conscious manufactures, especially when enhanced bioavailability and fast effect on-set are also among the top priorities.

Be aware that some articles in less-known peer-reviewed journals contain inaccurate and misleading information about nano- and micro- emulsions. Anyone interested in exploring cannabinoid-infused drink formulations should seeks advice from reputable journals or experts with relevant educational background and experience (For instance, consulting a politician on how to produce nanoemulsion might not yield reliable guidance).

References

http://dx.doi.org/10.1039/C5SM02958A

https://doi.org/10.3390/nano10081608

https://doi.org/10.1002/fft2.94

https://doi.org/10.1186%2F1556-276X-8-102

https://doi.org/10.3390%2Fpharmaceutics14030543

https://doi.org/10.1007/978-3-642-20665-8_116

https://doi.org/10.3109/21691401.2014.953633

https://ascensionsciences.com/newsroom/technical-articles/snapshot-analysis-nano-emulsification-formulation-technology/