Eliminating Cannabis Odors (bottom)

Caryophyllene is a Cannabinoid

Intro. to Aroma & Flavor



Hops (Humulus)

Articles & Papers

Measuring Flavor & Cannabinoids

Becoming a Flavor Scientist

Cannabinoid Molecular Structures


THCa-Tetrahydrocannabinolic Acid

CBD-Cannabidiol, Properties

CBN-Cannabinol, Properties












funny smell














































































































Carbon Filters Carbon Filters

Electrostaic Precipitator Electrostatic Precipitator


Flavor WheelFlavor Wheel (click)





Oxford Study Shows Caryophyllene (terpene) as a Dietary Cannabinoid

What does this mean? Cannabis ususally contains a significant amount of a terpene called beta-caryophyllene (BCP), which contributes to the aroma and flavor of cannabis. The study shows that this terpene, also found in other legal herbs, spices and food plants, activates the CB2 receptor and acts as a non-psychoactive anti-inflammatory. Because it binds to a cannabinoid receptor, it is considered a cannabinoid. WOW!

Question: Does non-psychoactive BCP compete with psychoactive compounds for receptor binding?; Can high BCP content reduce the psychoactive effects of cannabis?

Introduction to Cannabis Aroma and Flavor

The aroma and flavor of cannabis is manipulated by selective breeding for the biosynthesis of various classes of compounds. These include terpenes, flavonoids, alkanes and esters. Aroma and flavor molecules are generally volatile and posses lower boiling points than cannabinoids, thus they are released during vaporization processes.

Let's take a look at a class of molecules known as a terpenes, which contribute to give cannabis its unique bouquet and flavor. Some terpenes are said to modulate the physiological and psychoactive effects of cannabis. Additional research is needed into how these legal compounds participate in providing medicinal properties to marijuana.  Unfortunately, unjust Schedule I classification makes it illegal to extract perfectly legal compounds from cannabis.

Cannabis-Science recognizes that many terpenes in the botanical world exhibit medicinal properties and that a great number of modern pharmaceuticals were derived from this fact. Many cannabinoids are considered terpenes since they contain 'terpene-pieces' (moieties) assembled by the plant. Often, terpenes in the plant kingdom serve as evolutionary defense mechanisms to ward off predators and pathogenic microbes such as fungi and bacteria.


Terpenes (isoprenoids) are small molecules that consist of repeating units of a compound called isoprene. Terpenes play many important roles in the plant kingdom from deterring insect predation, protection from environmental stresses and as chemical raw materials for more complex molecules, like cannabinoids. Many plant terpenes act synergistically with other terpenes and some serve to either catalyze or inhibit formation of other compounds within a plant. Understanding the role of certain terpenes will allow scientists to manipulate cannabinoids to desired ratios, for example.


Isoprene is classified as an alkene. Alkenes are molecules with double bonds. Isoprene has 2.

Terpenes are made by many types of plants and are often the components of "essential oils". They are often times the building blocks to make more complex plant molecules, such as in certain hormones, vitamins (Vitamin A), pigments, sterols and cannabinoids. Others terpenes have antimicrobial properties, including some found in cannabis. Many of terpenes act as natural defense mechanisms against insects as resins are often sticky (i.e. amber, sap), while other terpenes such as limonene induce 'relaxation' and have their own unique pharmacology. Because of this diversity in the many functions of terpenes, whole cannabis (a.k.a. poly-pharmaceutical cannabis) has a higher therapeutic index than single-component THC (Marinol). This means, and medical marjuana patients affirm, that raw cannabis is superior in treating various ailments versus THC alone.

There are over 120 kinds of terpenes in cannabis, some only in trace amounts with others in double-digit percentage. Being able to measure these volatile compounds before and after a breeding experiment will offer the cannabis scientist endless opportunities for developing new flavors by basing breeding decisions on real analytical data.

More on Terpenes: Glossary and here.

CITRAL A & B Geranial/Neral/Lemonal. These are terpenoid compounds that contribute lemony scents to sinse. Check out wiki's definition w/ molecular structure.


The cannabis scientist should not only consider the genus Cannabis, but the entire botanical family Cannabaceae (aka Cannabidacea), which also contains the genus Humulus that includes the vine called hops. Understanding the terpene profile and biosynthesis in Humulus may provide cannabis breeders with insight regarding flavor/aroma profile manipulation.

Humulus (Hops, as in Hoppy India Pale Ale) is the only other genus besides Cannabis that is found in the family Cannabaceae; the two are genetically similar. Go to your local Homebrew Supplier and get an ounce of hops. A skunky variety such as Saaz will do. Compare the smell and physical similarities of the two Cannabaceae products. Smell familiar? Both have glandular trichomes that exude terpenoid-rich resin. Many of these resins not only add flavor to beer, but their orginal intent was to prevent spoilage via antimicrobial activity. Side-by-side the GC chromatograms from each plant would have many similarities (peaks).

Cannabis and Hops each contain some of the same essential oils. For example, each has significant amounts of oils called myrcene and caryophyllene which contribute to their characteristic smells. They are both aromatic terpenes that contribute to the spicy smell in both flowers. Limonene, also present in Cannabaceae, is an oil with citrusy notes, and it happens to also be found in citrus fruits. Perhaps there lies utility in this genetic similarity for developing new flavor/aroma lineage. Attempts to cross-breed and graft the two species have failed. But today, cannabis scientists can influence the biosynthesis of certain compounds with advanced genetic technology. Understanding how the Humulus vine is influenced may provide insight into the nature of cannabis, and vice versa.


MAKING IT HAPPEN - Becoming a Cannabis Scientist

The kinds of scientists whose work involves dealing with flavor, taste and smell includes Flavor Chemists, Fragrance Chemists, Oenologists, Biophysicists, and Neuroscientists to name a few. Biologists, Geneticists, Botanists and Horticulturists also get involved in manipulating flavor, smell and overall behavior of plants.


The majority of compounds responsible for flavor and smell are volatile, they tend to evaporate over time, going liquid to gas. To take advantage of this, Gas Chromatography is used to measure and identify the volatile components in a sample.

For example, say that you want to know the flavor/aroma profile for bananas. A sample of the banana would be dehydrated and then powdered. In theory, many of the compounds of interest are next extracted and dissolved by mixing the powdered bananas with a solvent. The exact mass of the powder and the exact volume of solvent allows easy calculation of %, later.

Meanwhile, a known volume of the solvent/flavor extract is fed into the gas chromatograph (GC). More on GC here. The GC displays a peak graphic for each compound. The size of the peak is relative to how much is there. So in our example sample, we found that the banana has... 8% iso-amyl acetate (classic banana smell), 2% amyl acetate and 1% nitrocelluslose.

For the technical side check out the CHEMISTRY page.

Basic Chromatogram


Eliminating Odor 

Although medical marijuana gardens are state-legal in 25% of the U.S. the federal fellows can still spend thousands of dollars to hire siz or seven guys to bust your three legal plants. More so, anti-cannabis neighbors remain ignorant about the cannabis community, often reporting medical gardens to authorities. Although your medical garden is perfectly legal, do you want to be served with a warrant and have your property searched, your rights ignored, rifle-bearing SWAT team break down the door, flash grenades, etc? Unfortunately, even legal medical marijuana patients should approach the situation from the federal standpoint and operate under the assumption that a permit is a failsafe, not a license to be overt. Legal medical gardens (even if only two plants) should be operated as clandestinely as possible and this means addressing odor issues…


The odor given off by flowering cannabis plants can be pungent and overpowering. The smell can be difficult to eliminatea while flowers are present, so it’s important to understand how to address such odor problems. The bottom line is to use multiple types of treatment at once.


Cannabis odor varies somewhat with maturity of the plant. Like formation of the cannabinoids, aroma molecules such as terpenes are made by the plant over a period of time. Several of these non-psychoactive oils are reported to have medicinal qulaities such as anti-inflammatory properties. Early in flowering these odors begin as light, flowery and sweet, and they increase in strength with flower maturity and resin production. Depending on the strain (genetics), the odor profile of cannabis generally develops into a skunky and sweet aroma as complex and variable as fine wines. There may be great variability in the aroma profile between two cannabis strains and/or even hybrid plants from the same mother.


With time, so much of these volatile oils are released into the air that eliminating the smell of flowering cannabis can be seemingly impossible. This challenge is best handled by attacking the problem from multiple angles at once. Cannabis odors are unique and to simply spray an aerosol deodorizer only adds to the odor profile, it does nothing to eliminate the odor. Use of Super Cinnamon Spray will give you the smell of cinnamon plus skunky cannabis.


Humans have a relatively keen sense of smell and can detect certain odors at very low concentrations. Often, the amount of odor-causing molecules in the air is at a level of parts-per-million (ppm). With this in mind it’s easy to see how an inefficient treatment regimen, perhaps a leak in a duct or use of an expired carbon filter, can still leave behind ppm-level odors that are still quite strong.


Because of the fact that use of sprays and incense only masks cannabis odor, many folks seem to think that deodorizers have no place at all in keeping odors from escaping the area. However, the key to fighting odor problems is to understand and utilize every tool toward the goal. This includes masking agents, but they serve a narrow purpose and it’s important not to overuse them; for your yard to smell strongly of PineSol on a daily basis is out of place and this could be a tip for already suspicious neighbors with a poor understanding of cannabis culture and truth.


Your cannabis odor treatment arsenal consists of:

  1. Mechanical
    1. Influx of Fresh Air (intake)
    2. Removal of Soiled Air (odor exhaust)
  2. Adsorption - Charcoal Filtration w/ Pre-filter
  3. Chemical Destruction - Ozone
  4. Electronic
    1. Ionizers
    2. Electrostatic Precipitators
  5. Masking Agents
    1. Cooking Food
    2. Aerosol Sprays/Oils
    3. Incense/Candles
    4. Carpet Powders
    5. Bubbling Solution

Ideally, the air in the grow room is contained by ensuring that the room is sealed, doors remain closed and the only openings include intake and exhaust ducts. Intake ports should be located near the floor. Exhaust ports should be located diagonally opposite (“kitty corner”) and on or near the ceiling so as to remove warmer, lighter air that collects near the ceiling. Because CO2 gas is heavier than air, the concentration tends to be lower near the ceiling and higher on the floor (CO2 monitors should be at plant level). The net effect of this intake exhaust arrangement is that cooler air is brought in near the floor at one end of the room and the exhaust air exits at the ceiling on the opposite side of the room. This creates an air flow that most efficiently uses CO2 and expels excess heat. Rooms that utilize CO2 supplementation are more efficient since fewer air exchanges are necessary to keep the CO2 level optimal, and fewer air exchanges reduces the frequency that soiled air is exhausted.




          The movement of air is critical for every treatment regimen and the mechanical aspects are foundational. Without proper mixing and movement, even the most effective treatment leaves stagnate pockets of foul air, especially in corners. For this reason, among others, it is critical for the air within the grow space to be circulating at all times. This is generally accomplished with an oscillating.


Mechanical treatment involves the physical movement of fresh and soiled (smelly) air to or from the grow space. With the use of fans and rigid or flexible ducting, fresh air is brought into the grow space and the net effect is dilution of the air, or a decrease in the concentration of odor molecules (ex: 100ppm to 20ppm). But keep in mind that any air pumped into an enclosed room will result in the same volume of smelly air being forced out of the room via displacement. This displaced air is considered exhaust. If the room is sealed then the untreated exhaust must exit through ducts or cracks and this becomes a liability.


Although dilution and removal of soiled air from the grow space may make the immediate area less smelly, the untreated exhaust may be headed directly for the neighbors house. Unless your grow space is equipped with an industrial smokestack that injects fouls air far above the community, then mechanical intake of fresh air and exhaust of soiled air is only effective at reducing odor within the grow space and adjacent rooms. Meanwhile, the once contained odor is now on the loose in the neighborhood, attic, basement, or wherever the exhaust duct exits. Additional treatment is required.


ADSORPTION- Carbon Filtration


Carbon filters designed for horticultural applications come in various sizes. Their official purpose in the market is to address the foul stench that sometimes comes along with use of organic fertilizers in confined spaces; otherwise, if designed specifically for cannabis cultivation, they would likely be outlawed.


Typically, carbon filters come in the form of a canister made of rigid duct components ranging from about 40cm to 1.5 meters in length. They are rated by airflow volume in units of CFM, cubic feet per minute (metric: cubic meters per minute) and the filter should be paired with a squirrel cage style blower of about the same rating


Carbon filters are a highly effective means of removing unwanted odors from air but there are a few things to keep in mind when using one. They have a limited lifespan and effectiveness depends on the age, odor load, humidity, size of the carbon particles, rate of airflow and air temperature.


As smelly air is drawn through the filter it passes over the carbon and the odor molecules (volatile organic compounds, VOCs) are adsorbed onto the carbon while the clean air passes through. Adsorption is the physical attraction of gas or liquid molecules to the surface of a solid. This attraction occurs because airborne odor molecules have a slight positive charge and are attracted to the cavernous activated carbon.


Essentially, a carbon filter is hung near the ceiling and attached to an exhaust blower using duct. The filter may be attached to either side of the exhaust fan – soiled air may be drawn into the filter or it may be expelled through the filter. In order to keep the filter cleaner and more inconspicuous, it is usually placed inside the grow space on the intake port of the exhaust fan.


For CO2 supplemented rooms that have no problem with heat buildup, keep in mind that instead of fresh air intake and subsequent exhaust, room air may be recirculated through the filter. This simplifies the setup, reduces vibrational noise, keeps the air moving and provides for more efficient odor removal.


Most carbon filters come wrapped in polyester batting that serves as a pre-filter that prevents dust particles from clogging the pores of the carbon granules. Activated carbon may be thought of as a sponge full of tiny pores and microscopic passage ways. Effectiveness of the filter is dependent on the number of pores present in carbon particles; the more pores there are, the higher the surface area of carbon and the greater the odor-removing capability since odors are adsorbed onto the surface of the carbon. Pore cloggage lowers effectiveness, impedes airflow, and generally leads to use of more electricity, so it is important to use the pre-filter and regularly clean it.


In the end, carbon filters are one of the most effective tools in your odor treatment toolbox. For those that are serious about odor removal, the extra cost is likely worth it.





Ozone is by far one of the most effective methods of odor removal but it carries with it potential hazards that MUST be considered. Ozone is an unstable gas that consists of three oxygen molecules (O3) and it has a very distinctive “electrical” odor. It is made whenever oxygen encounters a very high electric potential, and in nature lightning causes formation of ozone.


Because ozone is a high energy molecule, it doesn’t stick around long. It is a powerful, negatively-charged oxidizer and when it encounters odor molecules, it attaches to them and renders them odorless. The byproduct is oxygen (O2). Any unreacted ozone naturally degrades to O2 within about 30-90 minutes depending on the environment: temperature, humidity, etc. However, ozone itself can be hazardous to human (and microbiall) health because it such a powerful and reactive oxidizer. Ozone kills bacteria and fungi and so it can be useful in helping control funugus in humid enviromnets.


Some studies indicate that inhalation of ozone at very high concentrations can damage the lungs, eys or skin. For this reason it is critical that an ozone-treated space never be occupied by animals until the ozone has cleared naturally via degradation, or by fresh air exchanges.


Luckily, humans are able to smell ozone at low concentration. If you can smell it then get out of the space immediately and check back after an hour. It’s important to understand that ozone is a desensitizer and that brief exposures can decrease your ability to smell it minutes later, so never rely only on your sense of smell to determine whether ozone is present. As a condition, ozone should never be used unless you know how to calculate the exact amount needed, andit is prevented from entering living areas. This involves knowing the total air volume in the room being treated, and knowing the output of ozone from the unit, which is disclosed by the manufacturer. Concentrations greater than 0.04ppm (four tenths of one part in a million) are considered potentially unhealthy. Often this means that ozone generators may only need to run for 1-5 minutes. Anything more can be harmful to plants, pets and humans. Easy to use test kits are available that allow you to open a pouch and leave an indicator strip inside the ozonated room in order to determine ozone levels. Again, never use ozone in an inhabited area. With that said, a wall of skunk may be completely eliminated within minutes.


Ozone generators for horticultural applications come in a variety of styles. Some are safely contained and designed to be placed inline (inside of a duct) and use powerful UV lamps to produce ozone, which then enters the duct airflow and mixes with smelly exhaust gas to destroy odor molecules before exiting the duct. Other models use and electrical arc of several thousand volts to produce ozone. Some generators are external and designed to treat an entire room as opposed to the contents of a duct. Once again, it is critical to ensure that the air being treated is constantly mixed in order to distribute the ozone and eliminate pockets of foul air.


ELECTRONIC – Ionizers and Electrostatic Precipitators


Ionizers and electrostatic precipitators work on the same general principle by emitting negatively charged ions. Because odor molecules, dust, smoke, pollen and bacteria have a net positive charge, they are attracted to the negatively charges ions. The result is that the charge is neutralized, the odor molecule is quenched and it generally falls to the floor or sticks to the wall.


Ionizers or electrostatic precipitators are generally used in industrial HVAC air purification systems that handle large volumes of air, but are increasingly being used in home furnace and air conditioning systems. They are usually only one component of a multi-component system that may include pre-filters, de-humidifiers, HEPA filtration and carbon filtration, each component contributing to the overall cleaning of the airstream. Precipitators are large, stationary and depend on contaminated air being passed over them such that the contaminants are attracted to the charged metal blades, which require regular cleaning. Likewise, ionizers quickly acquire dust and this impedes efficiency.




Masking agents consist of chemicals and other odors that attempt to cover or hide pre-existing odors. They do not eliminate odors, they only manipulate the pre-existing profile in an additive manner.



One of the most useful, most natural and inexpensive masking approaches is simply cooking aromatic food. Cooking is an everyday act that is never out of place to visitors or repairmen, and it often does a reasonable job at masking odors within habited spaces. Of course, cooking everyday all day long is impossible for many folks but there is a wonderful, effective alternative – The Crock Pot. It is the least expensive and longest acting method of masking, produces no additional waste, avoids use of synthetic chemical sprays, feminine odors, and is efficient since you have to use electricity to prepare food already.


A crock pot is a valuable component in your odor treatment arsenal and too few people take advantage, sometimes opting for overkill sophistication when it is unnecessary. It is encouraged that you experiment with your favorite foods and spices to find the most effective recipes that suit your taste. For now, here is an inexpensive recipe that works well and takes minimal effort: Beans!


One cup of dry pinto beans costs only a few cents. They are first soaked overnight in cold water in order to soften them a bit. The next morning before work, the beans are placed in a crock pot with about 6 cups water and the setting placed to “high” to achieve a simmer. To be most effective you must add aromatic herbs or spices to the beans. Use of powdered or granulated garlic, 3-5 bay leaves, thyme, rosemary, etc. are very effective and give your home a warm and welcome ambience when folks come through the door.


While the beans simmer all day long, they fill the house with the good smell of cooking food, and when you come home from work, you may be surprised to find that the smell of cannabis in the living area is well masked. At this point late in the day, you have the option of adding potatoes, carrots, etc. Eventually, eating beans each day gets old. Not to advocate wasting of food, but keep in mind that even a half cup of beans with spices is effective and minimizes waste should you choose to throw the food out. Basically, your crock pot becomes a new form of potpourri and a little garlic goes a long way. You may wish to experiment with simmering water, bay leaves and garlic as a less hearty, broth alternative. Give it a try. Maybe grandma’s marinara recipe will do the trick!


If this method of odor masking is not something you wish to practice, at least keep it in mind as a component that can be combined with other methods to stack the odds in your favor. You may wish to do this on days in which family comes for a visit or a contractor is performing repairs on or near your property. But be prepared to answer the question “What smells so good?”


Did You Know? Did you know that many restaurants install ducts that carry kitchen odors to the entry and dining room so as to make the restaurant more appealing to customers and increase appetite?





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