DISCLAIMER: Here at Terpene Fresh we believe it is important to keep cannabis as fresh as possible from harvest to consumption. We also believe it is important to use plastic packaging responsibly. We are concerned with the modern proliferation of plastic products and the impacts they have on our environment. We take our craft and the health of the planet seriously. That is why we are continuously learning and sharing information, and why we have created this informational piece on the star component of our stand-up pouches: ethylene vinyl alcohol, or EVOH.

What is EVOH?

EVOH is a low permeable packaging material that reduces oxidation and increases shelf-life.

In the 1950’s, Kuraray Co., Ltd invented EVOH amidst the rise of supermarkets across Japan to address the growing need for plastic packaging materials capable of keeping foods fresher, longer. By combining ethylene with vinyl acetate, copolymer engineers successfully created a new, versatile material.

• EVOH is a thermoplastic, which means that if you heat it to its melting point it will liquify, so it is recyclable. Other plastics, called thermosets, burn when heated to their melting point, making them virtually impossible to recycle. 
• Composed primarily of carbon, hydrogen, and oxygen, EVOH does not contain bisphenol A (BPA), phthalates, or other substances that have been proven as endocrine disruptors.
• EVOH film is flexible and crystal clear. It has excellent flex-crack resistance, which means it is extremely durable under repetitive strain. It is highly resistant to hydrocarbons, oils, and organic solvents. 
• EVOH is sensitive to moisture, so it is often sandwiched between layers of other, less moisture-sensitive materials, like linear low-density polyethylene (LLDPE). This sandwich effect allows · · EVOH to fully work its magic, keeping out environmental spoilers. And in the case of Modified Atmosphere Packaging with a proper heat-seal, EVOH keeps in the right levels of the right gasses.

Why is EVOH important to cannabis?

From the moment a farmer cures their cannabis crop to the moment a consumer, well, consumes it, the cannabis decays just like any other perishable commodity. This can be bad news for the farmer and the consumer alike. As cannabis decays it loses potency, making it less marketable and less desirable for purchase. Additionally, its entourage effects change and degrade as the cannabis decays, making it difficult for consumers to know exactly what they’re purchasing at the dispensary. (Entourage Effects: the effects a consumer experiences from the synergistic interactions of cannabinoids and terpenes.)

So, to maintain the integrity of cannabinoids, farmers can use a high-barrier film that prevents oxygen from touching the product.

EVOH allows for exceptionally low permeability rates, which means it acts as a superior barrier to gasses like oxygen, nitrogen, and carbon dioxide. In a standardized test at 23˚C with 0% relative humidity, EVOH allows for an oxygen transmission rate (OTR) of just 0.005-0.12 cc/100 in2/24hr. Other commonly used plastic packaging materials, like low-density polyethylene, allow for OTR’s of up to 500 cc/100 in2/24hr.

Which would you prefer: a screen door that lets in 500 mosquitoes, or one that lets in just a sliver of a mosquito’s wing? Even if you are not a science-minded copolymer engineer, it is easy to see that EVOH allows far less oxygen to pass through it than other packaging materials. 

Because of its status as a high barrier film, EVOH is also particularly adept at keeping smell contained. And anyone transporting or carrying cannabis knows this is a huge deal.

Terpenes are responsible for the smell of cannabis, among other things (remember the entourage effect?). Exposure to oxygen causes terpenes to oxidize, change, and decay – and even encourages the growth of aerobic bacteria, which leaves cannabis with the smell of wet, rancid hay. Past the curing stage, where oxidation is desired to a certain point in order to allow terpenes to blossom into more complex versions of themselves, it is imperative to keep cannabis away from oxygen so that terpenes remain intact and capable of performing their role in the synergy that is cannabis.

When used in the cannabis industry, EVOH can be an absolute life saver. It keeps out more oxygen than other plastic materials on the market, and when combined with a metallized layer (as is the case with our metallized pouches), EVOH provides gas and light barrier properties that are just as good, if not better than glass – and far superior to other cannabis packaging products that are currently available.

Here’s the bottom line: next to growing the right strains in the right ways, correctly packaging cannabis is the most important consideration when it comes to providing a legitimate product, and EVOH is especially suited for the job.