Science for product makers: The importance of oxidation control in cannabis beverages

Potency stability remains one of the most important objectives of making cannabis infused beverages. Unlike most cannabinoids, liquor can be stored for decades without losing its alcohol content because ethanol is stable against degradation caused by oxidation. When cannabinoids are converted into a water-compatible ingredient such as nanoemulsion, the enlarged molecular surface area accelerates the oxidation process. This makes oxygen control especially important in this industry. In today’s article, we’ll explore preservation methods and shelf life considerations for cannabis infused beverages.

In spite of what you may think, it is possible to keep dissolved oxygen levels low in infused beverages

We’re not the only ones battling oxidation — oxygen is the enemy of the beer industry as well! Oxygen can quickly alter beer’s taste, even when the total ethanol content stays the same. But over the past couple of decades, the beer industry has been able to develop standardized systems to monitor and control oxygen. That’s why finished beer products from high quality breweries usually contain no more than < 50 ppb dissolved oxygen (DO). I think the cannabis beverage industry could learn a lot from their mature systems.

The key to controlling dissolved oxygen during beverage production is to combine an understanding of oxygen entry points and the right equipment with a mindset focused on quality.

In order to control DO during beverage production, it is important to first equip yourself with the right tool to measure it. I recommend products from Anton Paar and Pentair, which set the standard in this space. Keep in mind that the most accurate DO measurement can only be taken from freshly produced beverages. This is because DO may change (usually decrease due to oxidation reaction) during packaging as it sits in the warehouse.

Now that you’re able to measure DO, let’s talk about the 3 most important oxygen entry points in the beverage making process:

1. Oxygen removal: One of the first steps to controlling oxygen is to remove it from the water. This is usually done by purging CO2 or N2, which pushes out the oxygen. Especially when producing a carbonated beverage, certain in-line carbonators can do a fantastic job to reduce the DO in the water tank to < 50 ppb (DM me if you need a good recommendation).
2. Ingredient introduction: The next step we need to pay attention to is ingredient introduction. In my experience, the best method for avoiding introducing oxygen during this step is to connect a hopper directly to the main tank. Ingredients are added to the hopper under the protection of inert gas and then pumped straight into the main tank. Always keep a positive inert gas pressure (15-20 PSI)  in the tank headspace during the run. This is to minimize the chance of oxygen ingress into the tank. When liquid starts to flow through the pipe, be careful of the connection point — a deformed gasket could lead to oxygen introduction.
3. Filling: The last potential point of oxygen introduction is at filling. A counter pressure nitrogen sparging filler could minimize oxygen pick up.

The operation team’s mindset is critical throughout this process. Assuring quality requires patience, attention to detail and constant DO checks along the way. If you want to learn more about the oxygen control during beverage production and what equipment is recommended, you can download a copy of the Cannabis Beverage Manufacturing Handbook.

What if my current beverage co-packer cannot achieve this DO level?

Controlling DO at a level below 50 ppb is the gold standard for preserving cannabinoid potency and beverage flavor over a long shelf life. However, I want to recognize two challenges that exist in reality:

1. To control consistently low DO levels requires high value equipment, strict protocol and an experienced team. Not all cannabis beverage co-manufacturers can confidently achieve that today, so it’s common to see DO in the 200—1000 ppb range.
2. Even with a low starting DO level, certain packaging (PET and HDPE for example) may still allow oxygen to ingress into the liquid, continuing to cause oxidation during the product’s shelf life.

But don’t worry — there’s still a way to combat oxidation.

To address these realities of an emerging industry, we can leverage antioxidants to help maintain potency stability in cannabis beverages.

There are many different types of antioxidants, and they can be water soluble or oil soluble. The Vertosa team has tested many different types of antioxidants and we’ve found L-ascorbic acid (vitamin C) and Ethylenediaminetetraacetic Acid (EDTA) to be the most effective in delaying THC oxidation.

Vitamin C (L-ascorbic acid)

Vitamin C (L-ascorbic acid) functions as a sacrificial agent by reacting with oxygen before it has the chance to impact the cannabinoids. Given it is a widely used food acid and most cannabis beverages are at lower pH, it can naturally fit into most beverage formulations. Due to the oxygen level in ambient water, I’ve found that it’s safe to include 200 ppm of ascorbic acid into the formula in order to delay THC oxidation.

EDTA

EDTA functions as a chelator, which has a special chemical structure that binds with metal ions, such as Fe3+, Ca2+ and Mg2+. Those metal ions can accelerate the oxidation reaction in beverages by lowering the oxidation energy barrier. Binding with EDTA deactivates those metal ions’ impact to oxidation, which is how EDTA is able to control oxygen. The FDA has regulated EDTA to be used at max level of 33 ppm in finished beverages, which is an efficient level for our purpose.

Oxidation continues to be the biggest challenge for long term stability of cannabis beverages, but we need to take quality seriously to gain mainstream trust.

While the gold standard would be to reduce DO levels to < 50 ppb in finished products, the cannabis beverage industry is in its infancy and many manufacturers may not have the ability to control DO like more mature industries. I think adding antioxidants can be an effective solution. However, there is a discussion around Ascorbic Acid reacting with Sodium Benzoate to form Benzene. I will address this reaction in the next post.

What do you think? Have you had challenges controlling DO levels in your beverage products? Have you found other helpful solutions? Let me know in the comments!

Dr. Harold Han — the “Happy Chemist” — combines his storied background in emulsion chemistry and science with curiosity and fascination in the rapidly growing cannabis industry. Developing nano and micro emulsions his entire career, Harold holds a Ph.D in Surface Chemistry from NYU and is the holder of multiple patents for his inventions in emulsion chemistry.

As the Chief Science Officer at Vertosa, Harold spearheads the company’s development of industry-leading and customized active ingredients for infused product makers, offering pre-suspended aqueous solutions to create incredibly homogenous and stable products while maximizing bioavailability, clarity, and taste.

To learn more about the science of cannabis, make sure to follow Harold on LinkedIn and check out his Happy Chemist videos.