Addressing the Challenges of Hemp Drying: Cannabinoid Preservation and Fire Safety

Cannabis 1

Hemp, a crop with a hundred and one applications, is experiencing a global reboot. Market analysts predict hemp’s recent exponential global growth will mean a market evaluation of USD $26.6 billion by 2025.

hemp field

There is big money to be made in hemp, and farmers worldwide are jumping at the chance. The problem? A steep learning curve around the methods required to cultivate, process, and store this lucrative crop.

Post-harvest processing poses significant challenges, especially for flower-focused hemp cultivars grown for the growing cannabidiol (CBD) and oil extraction markets. Careful drying of hemp biomass preserves the valuable cannabinoids and reduces the risk of total devastation from mould, mildew and other pathogens. It’s in a cultivator’s best interest to find cost-efficient, safe, and effective industrial drying systems for their new crop.

Why Hemp Requires Post-Harvest Drying

Hemp, a cultivar of Cannabis L. sativa, contains more than a hundred different compounds known as cannabinoids. Hemp specifically is valued for its cannabidiol (CBD) content, a non-intoxicating molecule in hot demand for its application in pharmaceutical and wellness industries.

Cannabidiol is naturally a volatile compound. Before and after harvest, it goes through many transformations from one cannabinoid into another, transformations that are accelerated by excessive exposure to oxygen, temperature, moisture, and sunlight.

The first line of defense farmers have against cannabinoid loss post-harvest is through prompt and consistent drying in a dryer. Reducing moisture content within the plant material and flowers preserves the CBD and other relevant compounds, making the biomass much more valuable for foods, medicines, and cosmetics.

Drying also reduces the risk of pathogens like mould and mildew from infiltrating the raw material. If the drying process takes too long, doesn’t have proper ventilation, or the oven itself is contaminated, mould and mildew will proliferate within only a matter of days.

Solving the Inherent Challenges of Hemp Drying

Many of the challenges experienced by farmers today stem from a lack of proven processes. What is the best way to dry hemp on an industrial scale? What are the most fuel-efficient and cost-effective methods to capture the essence of the plant? Cultivators are struggling to find processing methods that preserve the yield quality.

Alvan Blanch has been drying hemp for over 30 years and the Conveyor Dryer continues to evolve alongside the modern hemp industry to solve many of the inherent challenges experienced by farmers and processors within the burgeoning hemp sector.

Our dryer, proven in other industries, is now rolling out worldwide for hemp and cannabis production. It addresses many of the concerns cultivators have with drying tech, including fire safety, cannabinoid preservation, and moisture content.

Conveyor Drier Alvan Blanch CD16000 - Hemp Drying System

Hemp Drying system – Switzerland

Alvan Blanch Hemp Dryer with Sprinkling System

Internal view of the Hemp Dryer with sprinkling system above drying bed

Fire Safety

As highlighted by a number of hemp-drying system fires across the US, one of the biggest concerns producers have is fire safety. As with other crops, hemp-drying operations are at risk of dust fires. An enclosed space, oxygen, heat, dispersion, and fuel may combine for a possible deadly outcome.

The solution is keeping temperatures within hemp-drying systems low and building in fire safety from the start. Our Alvan Blanch Conveyor system maintains a consistently low temperature of 80°C with some of our clients going even lower, between 40 to 60°C. Temperature largely depends on the product and final quality required. The low temperatures, combined with a protective mesh around burners and heat exchangers, plus a just-in-case onboard sprinkler system, ensure fire-safe drying even at an industrial scale.

Cannabinoid Preservation

The proper preservation of cannabinoids is another serious concern, especially for farmers hoping to sell their harvests for CBD extraction.

Cannabidiol has a boiling point somewhere between 160 to 180°C. Many secondary cannabinoids, also found in hemp, are even lower, starting around 105°C for cannabigerol (CBG). The low temperatures within our conveyor dryer protect the harvest’s value by carefully preserving even the most volatile cannabinoids. However, some volatiles evaporate at much lower temperatures, which is why some clients decided to operate at around 40 to 50° C.

Moisture Content

Nearly all advice on hemp storage recommends bringing it down to below 10 percent moisture content. Some resources, like Alberta, Canada’s Department of Agriculture, suggest even lower, around eight to nine percent.

The higher the moisture content, the more expensive the final cannabinoid extraction. According to an article on Hemp Grower from 2020, processing raw material with more than 10 percent moisture can drastically reduce the available cannabinoid content, perhaps by as much as 20 percent. For the farmer, that’s a substantial loss in value. 

What’s more, incorrect moisture content from drying can end up with disastrous results in storage. A few mold spores and the right humidity in a grain storage bag or warehouse can make hundreds of thousands of dollars’ worth of hemp unusable for any consumable market.

Our hemp dryers use a self-cleaning louvered bed system, which ensures that airflow is even across all parts of the dryer. This system achieves the desired less-than 10 percent moisture content and works well with the site’s HACCP system (particularly from a hygiene and process control perspective).

Ensuring Quality and Fire Safety in Post-Harvest Hemp Processing

Hemp cultivators are frantically catching up to the scientific advances made in other global crops over the last century. The best techniques for planting, harvesting, and processing practices are ongoing experiments.

Alvan Blanch is working alongside cultivators and processors to address the most common concerns (fire safety, cannabinoid preservation, and moisture content). For over 30 years our Continuous Conveyor Drying systems have provided efficient and cost-effective drying to the hemp sector.

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