After several recent high-profile recalls in the cannabis industry, the pressure is on cannabis manufacturers to ensure they consistently make safe, high-quality products that do not exceed microbial contaminant limits. Although many cannabis companies boast that quality is a top priority, the industry has not established quality management best practices, and manufacturers often do not employ best practices from parallel industries. The bottom line is, if a manufacturer wants to prevent a recall, protect its assets and its brand, it’s time to put some good practices in place. 

Proper Storage, Final Packaging, and Transportation Conditions

A batch of flower may pass initial microbial testing, but that does not mean it has the green light indefinitely. Just like any other natural product, microbes can get a foothold and return with a vengeance. Those microbes can be a direct threat to consumers, causing infection and illness, and some can produce mycotoxins and endotoxins that are also very harmful to human health.

It is essential to carefully monitor and control storage conditions across the lifecycle of flower products to prevent creating an environment where microbes can grow. The most important variables are the temperature and the relative humidity (RH) of the environment. Typically, dried botanical products are stored in a controlled room temperature or cool, dry place. The United States Pharmacopeia (USP) defines a dry place as an environment that does not exceed 40% RH, and room temperature and cool temperatures are defined as 68–77°F or 46-59°F, respectively.

In addition to controlling the temperature and humidity, it is important to protect the flower from extreme conditions, such as rapidly moving flower from cold to warm environments. This drastic change in temperature, which is common when transporting in non-environmentally controlled vehicles, can result in moisture condensation, which may allow microbial regrowth. 

The types of containers and packaging that are used to store flower products also deserve consideration. Tight storage containers that protect the product from light should be used to store bulk flower. Final products should be analyzed for water activity (aw), a measurement commonly used in the food industry to assess the moisture ratio between the water vapor of the product and surrounding air media. The USP recommends aw = 0.6 +/- 0.05 to prevent microbial growth without drying out the product and compromising quality. The American Herbal Products Association recommends dried botanical products be protected from excessive humidity by packaging in sealed containers with a moisture barrier and moisture control packs as appropriate. 

Detailed documentation and careful attention must be made around selecting final packaging materials and optimizing storage conditions within a facility, in transport vehicles, and at dispensaries to prevent microbial growth. As an added bonus, these conditions also protect the cannabinoid and terpene profiles of the flower, so proper storage is good all around.

Aseptic Handling during Downstream Processing

Although a batch of flower may initially pass microbial testing right out of dry/cure, downstream processing steps, like grinding, trimming, pre-roll filling, and packaging, can introduce microbes resulting in unsafe products and recalls. Therefore, flower in this stage should be handled “aseptically” as if it were a sterile product. To establish aseptic handling measures, a manufacturing facility should understand the critical control points within their processing steps that may introduce microbes, and they must take preventative action so they don’t undo all of the painstaking work they put in to grow cannabis clean.

Appropriate personal protective equipment (PPE) should be implemented in all post-harvest processes, and employees must be trained to use PPE properly and informed on hygiene protocols in the facility. It may seem like common sense, but do not allow anyone to touch product with bare hands or with gloves that have touched anything else but clean surfaces or product. For example, a gloved hand that touches a high-touch surface like a door handle or a cell phone is no longer clean, and the gloves must be replaced or disinfected before touching flower products.

Any surface that comes into contact with the flower must be disinfected regularly, including stainless steel tables, mills, auto trimmers, sheers, filling machines, and trim bins. It is important to inspect final packaging to ensure it does not have debris or dust and test packaging containers to confirm they do not have microbial contaminants. Confirmation of these disinfecting protocols must be performed via microbial culturing or with an ATP meter to detect any microbial life on these surfaces. Once established, these cleaning and validation methods ensure that post-harvest processing steps will not introduce contaminants that could result in a microbial failure.

In-House Quality Management and Shelf-Life Programs

In the pharmaceutical, food, and beverage industries, quality assurance and quality control (QA/QC) programs are required because they protect the company’s assets and the consumer by monitoring and controlling the facility, ingredients, processes, and final product. These programs are invaluable, but guidelines for QA/QC programs in the cannabis industry are not well established and rarely enforced. 

As the cannabis market rapidly expands, more budget-friendly technologies to measure key aspects of the product (potency, moisture content, and microbial contaminants) are available to manufacturers. These technologies can be used in-house to assess and improve processes, increase yield and potencies, and optimize conditions to ensure cannabis products are compliant and stay compliant over the lifespan of the product. 

It is the manufacturer’s responsibility to ensure the product they make will maintain its integrity until its expiration date, even after a product leaves the manufacturing facility and enters a retail or consumer environment. Shelf-life or stability programs are required in the pharmaceutical, food, and beverage industries, and they determine the expiration date by evaluating the integrity of a product over time under various environmental conditions. Key quality indicators, including qualitative analysis of the product, microbial burden, and active pharmaceutical ingredients (API) are all used to establish an expiration date that does not compromise the product’s quality or safety. Whether these shelf-life experiments are performed in-house or R&D samples are sent to third-party labs, the manufacturer must validate that their product is compliant over its reported lifetime.

Implement a Microbial Kill-Step

Virtually every food and beverage product must undergo some form of a “kill-step,” which is a step in the production process that removes harmful microbial contaminants to protect the consumer and preserve the product. In milk, it’s pasteurization; in beer, it’s boiling the wort before inoculating with yeast, then confirming the final product has conditions that inhibit pathogen growth (low pH and high percent alcohol). Implementing this kill-step is not intended to destroy every microbe on the product, but it is intended to significantly reduce “bad bugs” on the product to prevent these microbes from harming the consumer and/or limiting the product’s shelf-life (spoiling, decrease in API, etc.). Kill-step validation experiments provide assurance that the process reduces microbial loads, resulting in a consistently manufactured product that is compliant with microbial regulations.

A cannabis kill-step shares the same rationale as those found in food and beverage. Cannabis kill-step methods vary widely in their mechanism, integration into the process, ability to decrease bioburden, and their impact on the integrity of the product. They are not intended to act as a “magic wand” to conceal poor agricultural or manufacturing practices, but instead they must be integrated into the manufacturing processes to produce consistent and compliant products.

The Willow Team is here to Protect your Product from Recalls

At Willow Industries, we pioneered the cannabis kill-step using ozone technology to decontaminate flower products, significantly reducing microbial loads while retaining the integrity of the product. The WillowPure kill-step plays a key role in consistently passing third-party testing when integrated into a company’s good agricultural and manufacturing practices. Moreover, it locks in these low microbial levels over the shelf-life of the product, preventing the microbes from multiplying after the product leaves the hands of the manufacturer.

In the downloadable integrity shelf-life study, we demonstrate that WillowPure treatment significantly reduces microbial contaminants and keeps microbial levels low over the lifetime of the product. For example, without a WillowPure kill-step, untreated flower showed >630% increase in total yeast and mold (TYM) counts after 30 days of storage, reflecting the huge impact of integrating a kill-step into the process. 

Overall, if cannabis manufacturers want to avoid recalls and the bad publicity and financial losses that come with them, they must adopt these good practices and implement an effective kill-step, like the WillowPure ozone kill-step. These best practices will add up, resulting in a high-quality product that consistently passes microbial compliance testing and is safe for consumers.


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