Cannabis 101 

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Concentrate Shelf Life: How Long Does Cannabis Oil Last?

(aldra/iStock)

Finding a long-lost cannabis concentrate is a bittersweet moment. Your discovered concentrate was left stranded in a pair of jeans that had been stuffed in the far reaches of your dresser, untouched since that last camping trip. For about a year, it’s been sitting in between some parchment paper, waiting for you to unearth it.

The good news: no mold. The bad news: it doesn’t look like the translucent and golden “shatter” you once had. What’s before you now looks like a collection of off-yellow sugar crystals. Has this hash oil gone past its shelf life? Can you still enjoy it?

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How long a cannabis concentrate lasts depends on a number of factors ranging from the quality and classification of the starting material used to the packaging and storage of the final product. While some extracts and infusions can experience quality degradation in a very short time span, others may stay fresh and useable indefinitely.

The Impact of Extraction Method on Concentrates

The Impact of Extraction Method on Concentrates
(Julia Sumpter/Leafly)

Over time, some shatters will sometimes “sugar out” as their terpenes degrade away, leaving a substance with a higher concentration of THCA behind.

The golden standard in any extraction methodology is that the quality of the end product will always reflect the quality of the starting material. “Gold in, gold out; Garbage in, garbage out.” There’s a direct correlation between the quality of the starting material and what remains post-extraction. Inferior products containing compromised cannabinoid profiles will, in every case, result in an inferior extract.

Terpenes will almost always experience degradation of some kind during extraction. The loss will not only affect the flavor and medical efficacy of the final product, it could play a role in that product’s shelf life as well. Some products, such as those purposed for dabbing, utilize extraction methods intended for terpene preservation. Extractions meant for infusions such as for edibles, topicals, and tinctures  however, may not necessarily need to utilize these terpene preservation methods.

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Concentrates come in a variety of forms, ranging from extracts like saps, shatters, crumbles, butters, and distillates to sifted mechanical varieties like kief, ice water extract (IWE), and dry sift. Their attributes, such as consistency, viscosity, and clarity, are all byproducts of their extraction method.

The basic principle of an extraction is to remove the many impurities from the starting material, which include plant matter, fats and lipids, and other foreign contaminants. Many fats and lipids in solventless concentrates remain because they are more difficult to mechanically remove.

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Solvent extractions, on the other hand, produce “oleoresins” that contain a combination of cannabinoids, flavonoids, and terpenes, as well as other impurities such as fats and lipids, in many cases. Through a secondary solvent filtration process called “winterization,” these fats and lipids may be removed from a product, leaving behind a more purified substance.

The process of winterization is known to cause some terpene degradation that could compromise both the flavor profile and the consistency of the final product. However, this process is necessary for the production of super stable hash oil products such as glass-like “shatters,” as well as high terpene-containing saps and sugars.

Terpenes, Cannabinoids, and Concentrate Shelf Life

Terpenes, Cannabinoids, and Concentrate Shelf Life
(Julia Sumpter/Leafly)

The greatest perceived enemies of any concentrate, be it a wax, shatter, sap, or any cannabis oil-infused product, are all the same: light, heat, air, and time.

Concentrate varieties range in consistency from stable shatters and viscous saps to butters and sugary waxes. Each variety contains a different combination of molecules (e.g. cannabinoids, terpenes, lipids , impurities), but most carry a high concentration of the cannabinoid tetrahydracannabinolic acid (THCA).

The geometric structure of pure THCA is comprised of lattices stacked onto one another, forming a crystalline structure. However, THCA in a concentrate mixture will crystallize differently, depending on variables such as the ratio of other impurities present to agitation and temperature.

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For instance, “shatters,” known for their super stable glass-like consistency, are typically monocrystalline in final form, meaning they exhibit many properties consistent with amorphous solids (they have softer melting point ranges and appear less rigid in molecular structure) when exposed to varying concentrations of terpenes, impurities, or even other cannabinoids like CBD.

In order for shatter to maintain a glass-like physical structure, it must go through further filtration to remove these impurities. If left in a product, these other components can do many things, one of which is to cause a “buttering” effect in a concentrate when agitated or brought to varying temperatures.

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When terpenes or even other cannabinoids such as CBD are present in a concentrate, they can also act as emulsifiers (a mixing or solvating agent) to the crystalline THCA. A concentrate that is richly saturated in both THCA and in terpenes can take on different consistencies depending on how the product was agitated and at what temperatures that product was exposed to. These varying phases that concentrates exhibit (e.g. polycrystilline to amorphous) are largely influenced by the many impurities that prevent THCA from crystallizing.

Impurities can include anything from elevated levels of terpenes to fats, lipids, solvents, as well as the presence of other cannabinoids. For example, concentrates high in cannabidiol (CBD) will appear sappier due to the distinct structure of its molecule. 

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Over time, some shatters will sometimes “sugar out” as their terpenes degrade away, leaving a substance with a higher concentration of THCA behind. Although this process may compromise the experience a hash oil product may have once given, it’s not a final indicator that the product is unable to be used for vaporization (dabbing). Rather, it simply means that the molecular structure of the oil has changed as a result of the terpenes degrading out of the concentrate.

“Sugary”-like hash oils that were once “shatter”-like in consistency is our visual observation of what happens during terpene degradation, when THCA no longer has to worry about terpenes getting in the way of crystallization.

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Cool, dark, dry, still environments (refrigerators, freezers, low cabinets, freeze driers) are best for promoting longevity of your cannabis concentrates.

The greatest perceived enemies of any concentrate, be it a wax, shatter, sap, or any cannabis oil-infused product, are all the same: light, heat, air, and time. All of these elements facilitate the degradation of terpenes and cannabinoids, and will hasten the process by which some of your concentrates and infusions change.

Cool, dark, dry, still environments are best for promoting longevity, and when exposed to as few environmental contaminants as possible, some of these products will last a very long time without changing or losing anything.

Optimal storage options include refrigerators or freezers, low cabinets, or a freeze drier. These will help to eliminate the variables that tend to break down extracts. Over time, the cannabinoids (and, in some cases, terpenes) will inevitably change in some ways, regardless of condition. THCA will eventually degrade to cannabinol (CBN), a process which creates an “amber-ing” or darkening effect. Shatters and other dabble oils with higher terpene profiles may also sugar up, just like the one you found in your dresser.

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At the end of the day, that sugary shatter isn’t going to be a deal breaker. While your concentrate may not taste quite the same or give you that “full spectrum” feeling, a nice dab will still do the trick as those THCA crystals will still pack a punch.