The science of terpene degradation in hot climates

Terpenes are the aromatic compounds found in cannabis and many other plant species. Terpenes add great flavour, taste and character to your cannabis. But they are susceptible to degradation, especially in hot climates. High temperatures can cause terpenes to evaporate, oxidise and lose their aroma. Other factors such as prolonged exposure to heat, light, and oxygen can accelerate this degradation / decomposition.

In this article Dutch Passion explain why terpenes lose their impact and what you can do to prevent terpene loss.

Why terpenes gradually decompose - how you can prevent it

Cannabis connoisseurs store their cured buds in completely air-tight jars. This prevents a gradual in-flow of fresh oxygen steadily oxidising (chemically changing) the terpenes. The jars are best stored in a cool dark place such as fridge or freezer for longer term storage.

The cold slows down the natural decomposition of the terpenes. The darkness ensures there is no UV light which, over time, also degrades terpenes.

Maintaining cool, stable temperatures for your buds and minimising exposure to light/air is crucial for terpene preservation.

Cannabis terpenes - delicate and easily damaged

Cannabis terpenes give weed its distinctive aroma, whether you are growing from autoflower seeds or feminised cannabis seeds. The precise ratio of the various terpenes gives the strain-specific aroma. Terpenes themselves are a particular type of aromatic compounds. When pure, they are usually colourless or pale yellow in appearance. They evaporate slowly at room temperature.

Cannabis contains roughly 100 to 150 different terpenes, though the exact number varies by strain, growing conditions and the analytical methods used to detect them. Common terpenes in cannabis include myrcene, limonene, pinene, linalool, and caryophyllene. The concentrations differ across different strains and also between phenotypes of the same strain.

It should be stressed that these terpenes are easily lost through evaporation or though the effects of heat, light and oxygen. Once this happens, the aroma you once loved starts to fade. Here is more about the science behind that.

Factors affecting terpene degradation in hot climates

High Temperature:

Terpenes have varying evaporation points, but many begin to degrade or evaporate at temperatures as low as 70°F (21°C). Higher temperatures accelerate this process, leading to significant terpene loss, especially in unsealed (not fully air tight) containers.

Light Exposure:

UV light, especially direct sunlight, can degrade terpenes, causing them to evaporate and lose their aromatic qualities. Once chemically altered by light, the aroma fades. Cannabis is not the only natural product to be damaged by light. Wine is stored in dark coloured bottles to protect it from UV light which breaks down organic compounds, leading to off-flavors or ‘light-struck’ wine.

Oxygen Exposure:

Terpenes oxidise when exposed to atmospheric oxygen. This leads to a decrease in their concentration and a loss of aroma. Terpenes also evaporate when left in open jars. Always store your buds in air tight containers to prevent natural terpene loss through atmospheric evaporation.

Humidity:

While high humidity can be detrimental to some aspects of terpene preservation, low humidity can also cause terpenes to degrade or evaporate. Many connoisseurs use humidity-control sachets in their jars to maintain buds in their optimum state.

Storage Time:

The longer a product containing terpenes is stored without proper temperature and humidity control, the greater the potential for terpene degradation. Professional growers often insist on 100% airtight storage options such as those from CVault.

Note that whilst many terpenes don’t reach their boiling point until around 150ºC/300F, they will evaporate at room temperature. That’s why natural terpenes used as fragrances in fabric conditioners tend to lose much of their initial fragrance after a couple of days.

Signs of terpene degradation in your weed

Leave your weed in an unsealed jar and the fantastic aroma you worked so hard to achieve can be largely lost in a few days. You may be aware of several problems…

• Loss of aroma and flavour: 

  Terpenes contribute significantly to the aroma and taste of cannabis (and many other plants/herbs). Terpene degradation leads to a less pleasant and blander vaping/smoking experience.

• Reduced Entourage Effect: 

  Many cannabis fans feel that terpenes work synergistically with cannabinoids (such as THC and CBD) to produce a variety of effects. Loss of terpenes reduces the proposed entourage effect, potentially diminishing the overall experience.

• Changes in Psychoactive Effects: 

  Terpenes are thought to influence (or steer) the psychoactive effects of cannabis. Their degradation can alter these effects, making them less pronounced or even different. 

If you’re a real fan of juicy, terpy strains then check out the following review of Dutch Passion’s top-10 weed seeds for the highest terpene levels.

Recommendations for preserving your cannabis terpenes like a pro:

You work hard optimising your grow conditions, with quality LED lights, a fine-tuned grow method and good nutrient control. Ensure your buds retain that perfect finish for as long as possible by controlling these key parameters:

• Temperature Control: Store your weekly buds in a cool, stable environment, ideally between 60-70°F (15-21°C). An air tight, opaque container is ideal. If you don’t plan to touch your main stash for a couple of months it can be kept in the fridge or freezer where terpenes are extremely well preserved thanks to the low temperatures.

• Light Protection: Store your cured buds in opaque, airtight containers to minimise light exposure. UV light is powerful, it easily discolours ink on outdoor posters. Protect your precious buds from the damaging effects of long term light and store them in the dark, and preferably keep them cool.

• Oxygen Minimisation: Use airtight containers to prevent oxidation. Atmospheric oxygen slowly changes the structure of many chemicals through a process known as oxidation. Leave any terpene-rich material exposed to a fresh stream of oxygen-rich air for long enough and it loses much of those terpenes. Some terpenes are lost instantly due to atmospheric dilution. Some slowly decompose as atmospheric oxygen slowly degrades and changes the terpenes into natural decomposition products. A common example of rapid terpene loss is with freshly roasted/ground coffee bean packs. Once the pack is opened that initial intense blast of coffee-scented terpenes is lost to atmospheric dilution. Leave the coffee pack open/unsealed for a few days and the taste will be permanently diminished.

• Humidity Management: Many use humidity controlling sachets such as those from Integra, Boveda etc to ensure a steady 62% (or so) humidity in the jars/CVault.  This helps the buds maintain a perfect level of freshness. Cigar connoisseurs also use humidity control to ensure optimised preservation.

• Proper Curing: Ensure proper curing to retain the terpenes in your buds.

• Drying your plant with the leaves on. Drying the buds/blooms with leaves still attached is an old-school tip believed to allow more terpenes to remain in the buds during the drying process. Often blooms are dried with leaves still attached by those who prefer dry-trimming more than wet-trimming. Hanging the blooms upside down during drying has also been claimed to increase/protect terpenes. Some growers claim that wet-trimmed buds lose terpenes more easily than blooms that were dried with the leaves attached. 

Understanding the various factors that contribute to terpene degradation/evaporation allows you to implement the appropriate preservation strategies.

If you love terpy weed then it always helps to start with cannabis seed varieties that enjoy naturally high terpene levels. One of the highest terpene levels seen recently by Dutch Passion QC team was with the notorious Blue Zushi strain which produced a throat rasping 2.6% total terpenes - FYI typical terpene levels are nearer 0.75% in average street weed.

........