Tag Archives: mold

March 22, 2017

Preventing Yeast and Mold with Two-Way Humidity Control

By Aaron G. Biros

When a grower harvests their cannabis plants, they process it by drying, curing and trimming the plant material. Dried cannabis ready for the consumer can often sit on retail shelves for months before it is purchased. According to the Cannabis Safety Institute, trimming is the processing stage with the highest level of human handling, and thus presents the most significant opportunities for microbiological contamination.

The Cannabis Safety Institute recommends workers handling dry cannabis wash their hands periodically, generally conform to food safety rules and wear gloves at all times. In addition to these tips, looking at relative humidity is a good tool to mitigate contamination concerns like the growth of yeast and mold spores. Mold spores can grow quickly when there is enough moisture, but if the cannabis is dry enough, mold spores cannot develop.

Growers controlling the relative humidity of their finished product in the past often placed an orange peel or a wet cotton ball in a jar with dried cannabis to retain the weight from water and keep it from over-drying. Those tactics have since been improved upon using modern technology.

Water activity is a measure of the relative humidity immediately adjacent to the product, according to Bob Esse, vice president of research at Boveda. “Cannabis’ relative humidity will reach equilibrium with the surrounding environment over time, which is why it is so critical to manage this adjacent atmosphere,” says Esse. “Moisture content is the total water present in the product and is a variable that changes in its relationship to water activity from one strain or type of product to the next.”

Back in 1997, Boveda first patented two-way humidity control. For the last 20 years, that company has made humidity control products for packaging in a variety of industries, like wooden musical instruments, pharmaceuticals, medical devices, electronics, tobacco, photos and documents and perhaps most notably for keeping cigars at the right humidity level in a humidor. According to Charles Rutherford, business development director at Boveda, he saw people buying their products meant for cigars, but using them with cannabis. About six years ago, they started developing a product specifically for the cannabis market.

The science behind it is relatively simple, says Rutherford. “Certain salts saturated in water can naturally regulate humidity- we just developed a cannabis-specific humidity level and patented the packaging around it that purifies the water and can come in direct contact with cannabis,” says Rutherford. “Using water activity meters and a moisture isotherm test, we determined the most appropriate range of humidity levels that cannabis will remain stable.” That range turned out to be between 59% and 63% humidity level for the properties in dried cannabis to stay the same.

According to Rutherford, it is a little more complex than just a range to stay in. “There are different humidity levels that certain strains prefer, but there are personal preferences, regions and other factors to consider when determining the levels of humidity ideal for cannabis,” says Rutherford. “We wanted to understand what people consider to be perfect.” In their research they found that depending on the region of the country, that humidity level varies considerably. “Using a water activity meter we could tell exactly what people prefer,” says Rutherford. Colorado, for example, prefers significantly drier cannabis than the Pacific Northwest, according to their findings.

Right now, Boveda has two-way humidity controllers set at 62%, 58% and soon they will have an under 50% option (appealing to the Colorado market). Using a device to accurately control the humidity level in cannabis can help growers and retailers prevent contamination from the biggest source of concern: water. “There is a ton of talk about pesticide contamination, but the reality is even if the flower is grown organically, you can still encounter safety problems when the moisture level is off,” says Rutherford. From a medical perspective, keeping dried cannabis at an ideal humidity level helps stabilize the properties of it, maintaining the medical efficacy. “If this is something people use for a medicine, it should be at an ideal condition,” says Rutherford. “Quantifying and understanding what humidity level is right is what we are helping accomplish.” For patients with compromised immune systems that need safe, consumable cannabis, a humidity control device can help prevent contamination and ensure a certain degree of safety in their medicine.

On a retail level, the packaging insert can extend the shelf life of products and maintain the quality. “The world has known for decades that 70% humidity level for cigars is ideal,” says Rutherford. “The cannabis world hasn’t had a moisture standard or understanding of what is proper until very recently.” That 62% humidity level determined after commissioned testing is a good standard to reference when determining your own ideal humidity level.

Growers also recognize the value in keeping their cannabis at the right humidity level beyond the obvious safety concerns. “As cannabis dries out and loses its humidity, the overall weight is reduced,” says Rutherford. “Precision humidity control gives a uniform humidity throughout the flower, leaving out the mystery for growers and maintaining weight, meeting the nexus between quality and weight.” According to Rutherford, growers have an incentive to package their cannabis a little on the wet side. “Because it weighs the most when wet, it is sold by weight and it will lose moisture over time, the incentive to deliver product that will dry out over time- that can create a lot of problems by having high moisture content.” For the first time ever, people can dramatically extend the shelf life of dried cannabis, instead of letting products naturally deteriorate and go bad over time. “For the first time ever, it allows you to extend the shelf life of dried cannabis for aging cannabis like wine and cigars,” says Rutherford.

The data from that Cannabis Safety Institute report, collected by AquaLab and CannaSafe Analytics using a vapor sorption analyzer, shows a cutoff of 65% relative humidity. These findings give the industry a lot of guidance in working to reduce the amount of yeast and mold contamination, says Bob Esse. “If your dried cannabis is above 65% relative humidity and you are a retailer, you should send that product back to the grower because it wasn’t dried properly, is vulnerable to mold and yeast spores and thus not safe for the consumer,” says Esse.

Pointing to the report, Esse says foods with high moisture content are able to support robust microbial population growth, which can lead to bacterial and fungal infections. “Water activity is what impacts whether microorganisms can grow or not.” By using two-way humidity control technology, growers and retailers can mitigate risks of contamination, improve quality and extend the shelf life of their products.

February 8, 2017

Colorado Cannabis Lab Methods Updated for Microbial Testing

By Aaron G. Biros

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The Colorado Department of Public Health and Environment’s (CDPHE) Marijuana Laboratory Inspection Program issued a bulletin on January 30^th regarding updates required for licensed cannabis testing labs. The updated method for microbial contaminant testing includes a longer incubation period in yeast and mold testing.

“After careful consideration of emerging data regarding the use and effectiveness of 3M Total Yeast and Mold Rapid Petrifilms in marijuana, CDPHE has concluded that 48 hours is not a sufficient incubation period to obtain accurate results,” the letter states. “Based upon the review of this information, marijuana/marijuana products require 60-72 hours of incubation as per the manufacturer’s product instructions for human food products, animal feed and environmental products.” The letter says they determined it was necessary to increase the incubation period based on data submitted from several labs, along with a paper found in the Journal of Food Protection.

An incubator (Right) at TEQ Analytical Labs

According to Alexandra Tudor, manager of the microbiology department at TEQ Analytical Labs (a cannabis testing lab in Aurora, CO), the update is absolutely necessary. “The incubation time extension requirement from CDPHE offers more reliable and robust data to clients by ruling out the possibility of a false yeast and mold result during analysis,” says Tudor.

Alexandra Tudor, microbiology department manager at TEQ Analytical Labs

“3M, the maker of Petrifilm, recommends an incubation time of 48-72 hours, but during TEQ’s method validation procedure, we learned that 48-hour incubation was not sufficient time to ensure accurate results. Although some laboratories in industry had been incubating for the minimum amount of time recommended by the manufacturer, the 48-hour incubation time does not provide a long enough window to ensure accurate detection of microbiological contaminants present in the sample.” Tudor says the update will help labs provide more confident results to clients, promoting public health sand safety.

As a result of the update in testing methodology, cultivators and infused product manufacturers in Colorado need to submit a batch test for yeast and mold. The point of requiring this batch test is to determine if the producer’s process validation is still effective, given the new yeast and mold testing method.

March 23, 2016

A Case for Compartmentalization: Problems with Perpetual Harvest Models in Cultivation, Part I

By Adam Koh

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When newspapers and television run a cannabis story, it is frequently accompanied by photos or video of vast, cavernous warehouses filled with veritable oceans of plants. Photos used to illustrate stories in the New York Times and Denver Post serve to illustrate this point.

This type of facility design is sometimes referred to in the cannabis industry as a “perpetual harvest” model. This is because plants are harvested piecemeal – one row at a time, for example – with new plants ready to flower replacing the recently harvested ones. In this model, flowering plants of various ages occupy the same space and the room is never completely harvested and empty, hence the “perpetual” moniker. This is in contrast to more compartmentalized facility designs, in which flowering plants are segregated in smaller groups in various rooms, which are then harvested completely before the room is cleaned and new plants ready to flower replace the previous ones.

The perpetual harvest setup appears impressive and lends itself well to portraying the volume of production being achieved in large facilities. This is likely why I have seen such models, or similar ones, copied in other states. Prospective entrants to the industry have also approached my firm with such designs in mind for their cultivation facilities. However, we generally advise against the perpetual harvest facility model, as this type of design imposes serious difficulties upon operators. Problems arise primarily in the areas of pest and contamination mitigation, ability to properly observe pesticide use and worker safety guidelines, and inefficiencies in lighting and HVAC usage. The problems noted are linked to the perpetual harvest design and can be mitigated with increased compartmentalization. Before getting to my recommendations, however, lets run down the issues created by the perpetual harvest model.

AdamKohcultivation — Photo credit: Denver Post

Lighting and HVAC Inefficiencies

In many photos I see of perpetual harvest facilities, the ceilings are extremely high, as are the light fixtures in most cases. This is likely the result of one of the main perceived advantages of such spaces, which is that they require minimal construction prior to getting up and running. There are no walls to be put up or ceilings lowered, and the lack of compartmentalization makes running wires and ducting much easier.

However, whatever capital was saved in initial construction will likely be burned up by increased ongoing operational costs. High ceilings such as those in the above photos mean more cubic footage that climate control systems must cool or heat. Additionally, due to the great height of the light fixtures, plants are not getting the most bang for their buck, so to speak, compared to designs that allow lights to be lowered appropriately to provide optimal intensity and spectrum. Double-Ended High Pressure Sodium (DE HPS) lamps are probably the most common type of lighting in use for flowering by commercial cannabis cultivators today, and they are ideally situated about four feet above the canopy when running at full capacity.

For businesses aiming for a no-frills production model with minimal attention to the light management needs of individual cannabis cultivars (or strains, as they are commonly referred to), then this consideration may be moot. However, those operations attempting to produce the highest-quality flower and plant material know the value of proper light management, as well as the fact that some cultivars respond differently than others to intense light. Indeed, I have observed cultivars that produce more when light intensity was decreased, while others thrived under intense light that would have seriously damaged others. This makes the one-size-fits-all approach to light management I’ve seen in most perpetual harvest designs generally detrimental to the quality of the final product, in addition to using the same amount of energy, or more, to achieve that lower quality result.

Difficulties in Pest and Contamination Mitigation

Such a design makes it easy for a small pest incursion to become a full-blown infestation. Because plants about to be harvested are sharing space with plants just beginning their flowering process, this means that both current and future harvests will be affected, or even lost entirely if the pest problem is severe. Having plant groups of different ages share the same space is generally unadvisable. This is because older plants, particularly those close to harvest, are weaker and more susceptible to pests by virtue of the fact that their life cycles are nearing an end. On the other hand, a more compartmentalized facility design provides physical barriers that can contain mites and mildew spores to some extent, limiting the damage done by individual pest incursions.

One of the essential tasks in an indoor cultivation operation is sterilizing just-harvested spaces to ensure that the subsequent run gets off to a clean start. This task could conceivably be performed in a perpetual harvest model; say, for example, trays, trellis frames, and other equipment are scrubbed after a row has been cut down and removed for drying or processing. However, due to the fact that there are always other plants in the room, it seems impossible for any plant group to get an assuredly clean start, as other plants may be harboring bugs, mold spores, or viruses, despite not showing signs or symptoms. The presence of plants also eliminates the possibility of using cleaning agents such as bleach, which gives off harmful fumes, but is sometimes necessary to completely sterilize an area that might have previously experienced some amount of powdery mildew or botrytis.

In Part II of this series, I will discuss some problems with pesticide use and worker safety regulations as well as provide recommendations for compartmentalization in cultivation facilities. Stay tuned for Part II of A Case for Compartmentalization: Problems with “Perpetual Harvest” Models in Cultivation, coming out next week.