What Is Log Reduction, And What Does It Measure?

In microbiology “log reduction” is a measure of how effective a process is at reducing pathogens. The greater the log reduction the more effective the process at killing pathogens. ‘Log’ is short for logarithm, a mathematical term. Every ‘log’ increase is a 10-fold increase. For example, 3-log is 103 or 10 x 10 x 10 = 1,000.

A log reduction takes the power in the opposite direction. For example, a log reduction of 1 is equivalent to a 10-fold reduction or, the final count is 1/10 of the original count. So, the percent reduction is (1 - 1/10) x 100 = 90%.

To determine the log reduction, microbiology labs count the number of colony forming units (CFU/g) of a given pathogen, e.g., TYMC,  in a product before treatment. Then another sample is sent after APEX treatment for the measurement of CFU/g of the same pathogen. The result of the difference between the ‘before’ and the ‘after’ is expressed as a Log Reduction.

As a basic rule of thumb, for every additional Log reduction number you add a 9 to the percentage reduction – so a log reduction of 3, as illustrated above is (1 - 1/1000) x 100 = 99.9% reduction compared with a log reduction of 6 which is equivalent to a 99.9999% reduction.

Will We Pass Microbial Testing?

Treatment with Radio Frequency is proven to reduce Total Yeast and Mold Count (TYMC) by more than 99.9% and comply with regulatory requirements. Radio Frequency is also effective in addressing other testing criteria such as Total Aerobic Microbial Count (TAMC), Bile-Tolerant Gram-Negative (BTGN), Coliforms, and Aspergillus.

Will Radio Frequency Fix Powdery Mildew?

Unfortunately, no. As the mold advances, visual impairment occurs. There is no remediation process that can remove the powdery mildew. The recommendations are to improve your upstream processes prior to harvest, manage the post-harvesting process effectively, and remediate with radio frequency.

Will Radio Frequency Address Pesticides and Heavy Metals?

No, it will not.

Can RF Treat Penicillium?

Penicillium is a type of mold. It can be found naturally in the environment (soil, decaying vegetation and air).

Like any other microorganism, Penicillium family includes a wide range of species from which a few have been proven to be very beneficial to humans; for example, antibiotic penicillin is produced by Penicillium, and the mold used in making Camembert cheese is from the Penicillium family.

On the other hand, a lot of Penicillium species are considered contaminants, and some even can cause infections in humans or produce mycotoxin.

Knowing that RF is effective in total yeast and mold reduction, it is expected that RF can reduce Penicillium population.  However, we do not have data specifically related to Penicillium species on cannabis, and cannot predict specific log reduction.

Does RF Kill Mycotoxins?

Mycotoxins such as aflatoxins are naturally occurring toxins produced by molds such as Aspergillus. These toxins can be the root of a variety of adverse health effects in both humans and animals. Immune suppression (weakening the immune system) and cancer are among aflatoxin- associated health effects. Most mycotoxins are chemically stable and are not completely destroyed during food processing. To eliminate these compounds, more complex and severe processing conditions are required.

In the past we have tested the effect of RF on reduction of aflatoxin in corn and observed some reduction in aflatoxin concentrations at high temperatures (110-120°C). We do not have any data on the effect of RF on mycotoxins in Cannabis. However, based on previous experience, one can say that the RF process time and temperature for reduction of microbial population in Cannabis is not sufficient to destroy mycotoxins.

Do Your Cultivators Identify Common Molds in Their Facility or in the Product First?

Unfortunately, most customers do not take the step to identify the common molds in their facility or product, which can be very helpful in strategic planning and prevention. Interestingly, we recommended that approach a while ago to one of our customers, but they were not interested.

As such, we do not have any data comparing sensitive and resistant yeast and molds in the RF process. Our Cannabis data is on total yeast and mold counts.

We consider mold spores as representative of resistant molds, due to their ability to survive harsh environmental conditions. Attached is a white paper from the effect of RF on Aspergillus spores in corn. The study was done a few years ago, showing the effectiveness of the RF process in general in the reduction of the number of spores.

Does The APEX Work on Bile-Tolerant Gram-Negative Bacteria?

Bile-tolerant gram-negative (BTGN) bacteria are a group of bacteria that have the ability to survive the harsh condition of the human stomach. They are equipped with a membrane that protects them against a wide range of chemicals such as detergents and antimicrobial enzymes or even many antibiotics. Some bacteria from Enterobacteriaceae, Pseudomona and Aeromonas families are members of the bile-tolerant gram-negative bacteria. They are widely spread in the environment.

In the USA, the regulatory agencies that use American Herbal Pharmacopoeia's Cannabis Monograph as a reference for defining the acceptable microbial limit in Cannabis require testing for bile-tolerant gram-negative bacteria with an acceptable limit of < 1000 CFU/g. Washington, Massachusetts, New Mexico, New York, Illinois, and Ohio are among the states with required testing for bile-tolerant gram-negative bacteria.

Canadian regulations require testing for bile tolerant gram-negative bacteria in Cannabis. Ziel has limited experience with remediation of BTGN, however, at this point Ziel doesn’t have adequate data to predict expected log reduction of BTGN with Baseline recipe.

Can RF kill aspergillus?

Ziel has limited experience due to relatively less frequent occurrence of aspergillus. However, in limited production runs on cannabis flowers that tested positive for aspergillus APEX was able to successfully bring that product to compliance.

Visual chart showing how radio frequency removes mold, yeast, and bacteria to safe levels in cannabis and will not regenerate or grow back if water activity levels are below a 0.65 threshold, avoiding a cannabis recall.
Does Regeneration Occur After Product is Treated with Radio Frequency?

No. As the chart details, as long as the water activity level is below 0.65, molds, yeasts, and bacteria will not grow back. Certificates of Analysis usually measure water activity levels. In addition, some states require water activity levels < 0.65 or 0.60 to ensure product stability after it is placed in retail dispensaries.