Investigating Aromatic Esters, Thiols, and Aldehydes in Cannabis

Esters, thiols, and aldehydes are organic compounds found in many plants, including cannabis, that correlate with sweet or savory aromas. Terpenes get a lot of attention for influencing the smell and taste of everyone’s favorite cannabis strains, but esters, thiols, and aldehydes also play a major role.

This article explores how cannabis esters, thiols, and aldehydes shape strain aromas and why testing these compounds can refine strain development and therapeutic potential.

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What Are Esters, Thiols, and Aldehydes?

Esters, thiols, and aldehydes are volatile organic compounds that contribute to cannabis and hemp’s full spectrum aroma and effects.

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What Are Esters?

Esters are organic compounds that appear in many everyday products, including food, cosmetics, medicines, and soaps. They form from a condensation reaction between alcohol and carboxylic acid (known as esterification). They comprise the numerous ingredients with the suffix “ate” on the back of labels.. 

In nature, esters give plants and fruits their pleasant smells and flavors. They are also well-known brewing flavorings during yeast fermentation in alcohol 

Notable esters include:

• Ethyl butyrate in pineapples
• Methyl salicylate in wintergreen
• Propyl ethanoate in pears
• Ethyl propionate in rum

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What Are Thiols?

Thiols are sulfur-containing organic compounds. They are similar to alcohols and phenols, except that they contain a sulfur atom in place of an oxygen atom. 

Due to their sulfur content, thiols are often responsible for pungent aromas, like freshly chopped onions or warning odorants in fuel gases. 

Examples of thiols include:

• 2-butenethiol in the defensive spray of the skunk
• 2-propanethiol in the breath of people who have eaten garlic
• Furfurylthiol in the aroma of fresh coffee

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What Are Aldehydes?

Aldehydes are aromatic compounds created through the dehydration of alcohol. They have a double bond between oxygen atoms and carbon atoms, which makes them more volatile. 

Their structure results in pronounced scents that range from pleasant and sweet to pungent and nauseating. Aldehydes are responsible for intense smells like cinnamon bark, vanilla bean, rose, citrus, and more. Scientists often create them synthetically for perfumes and colognes.

Notable aldehydes include:

• Acetic acid gives vinegar its sour taste and pungent smell
• Benzaldehyde smells like almonds
• Citral gives lemons their aroma
• Hexanal resembles freshly cut grass
• Methyl anthranilate has a fruity grape smell

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Significant Esters, Thiols, and Aldehydes in Cannabis 

Esters, thiols, and aldehydes affect smell profiles throughout nature, and they play a major role in crafting the intricate bouquet of scents associated with the cannabis plant.

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Cannabis Thiols: Why Strains Smell Skunky

In 2021, scientists at Byers Scientific revealed that thiols in cannabis are responsible for the plant’s distinctive “skunky” aroma. 

In particular, 3-methyl-2-butene-1-thiol (321 MBT), a sulfur-containing thiol and one of seven thiols found in a skunk’s spray, is the main culprit behind the “straight skunky smell” of popular cannabis strains such as OG Kush.

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Cannabis Esters: Why Strains Smell Fruity

Similarities in aroma between fruit and many strains can be uncanny at times, which recent reports found is more due to esters in cannabis than terpenes. 

The new research identified 30 esters in cannabis, each with different aromatic characteristics—even within a single variety. 

Some of the most popular commercial cannabis cultivars boast flavors of banana, strawberry, or pineapple, such as Strawberry Banana and Pineapple Kush (a mix of Master Kush and OG Pineapple). Esters that lend these strains their namesake fruity profiles include:

• Ethyl hexanoate with a fruity, apple-like aroma
• n-propyl hexanoate with a scent of blackberry and pineapple
• Ethyl caproate found in exotic, fruity, tropical fruits

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Cannabis Aldehydes: Scent-Enhancers

There is less known about the role of aldehydes in cannabis, but one theory is they work as “scent boosters,” making cannabis strains smell more potent and alive. 

A study focusing on the terpenoid and cannabinoid profiles of inflorescences from five different varieties and four intra-specific cannabis hybrids found three primary aldehydes and all of them prominently serve as scent additives in many commercial products:

• Decanal offers a powerful, sweet, orange-peel aroma that enhances perfumes, soaps, shampoos, and more. 
• Nonanal is a natural fragrant component used in trace amounts to add “bloom” and enhance floral and citrus notes in perfumery products. 
• Undecanal enhances the sensory experience of many consumer products with its fresh, citrus scent.

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Possible Therapeutic Applications

There is evidence that esters, thiols, and aldehydes contribute more than scent to various cannabis strains. These compounds could also enhance the plant’s therapeutic benefits, fighting stress, germs, and more. 

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Health properties of esters in cannabis 

Esters are often found in essential oils and floral waters, and they have properties such as antispasmodic and calming effects.

• According to a study by Food Chemistry, certain esters have potent antioxidant properties with the potential to be functional food ingredients. 

• Another study showed that cannabidiolic acid methyl ester had high potential as a medicine for treating nausea and anxiety disorders. A follow-up found the ester might modulate the sleep-wake cycle by engaging the hypothalamus.

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Stress-relieving effects of thiols in cannabis

Plants produce thiols because they play an important role when it comes to stress responses. Research suggests these antioxidant properties might have medical applications. 

• One review says thiol-containing drugs can reduce free radicals and other toxic electrophiles. 

• Another study discusses how thiols have evolved to “take full advantage of a world of molecular oxygen.” In doing so, they can protect organisms from oxidative and imbalances from foreign substances. 

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Antimicrobial benefits of aldehydes in cannabis

Aldehydes in industrial applications have noted preservative and anti-bacterial properties.

• An aldehydes study found these compounds can alleviate the phenomenon of antimicrobial resistance. They can also function as antibacterial and antifungal agents, balance menstrual cycles, and serve as immune-system boosters. 

Comparing Esters, Thiols, and Aldehydes

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What Testing for Esters, Thiols, and Aldehydes Means for Cannabis Strains

Esters, thiols, and aldehydes bring more to the scent and flavor table than many previously realized. Cannabis is very complex in its chemistry and the way its many compounds interact with one another. Although these small molecules appear in trace amounts, studies show they can have a big impact on cannabis odor and taste. Testing for ester, thiol, and aldehyde content and understanding more about them can have enormous implications for cannabis strain development. 

• Building a formula inspired by terpenes alone might not address the full spectrum of odors.
• Contributions of esters, thiols, and aldehydes to cannabis scent provide a new opportunity to classify varieties using key desirable aroma attributes.
• Cultivators can neutralize unwanted, pungent odors and enhance preferred ones more easily. 

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The Bottom Line

Esters, thiols, and aldehydes are minor compounds behind the big flavors in many popular cannabis strains. They also have therapeutic implications, possibly contributing stress-relieving and immune-boosting benefits. 

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As the Most Trusted Cannabis and Hemp Laboratory in the USA™, ACS Laboratory is exploring advanced testing methods for esters, thiols, and aldehydes. Would you want to test for these groundbreaking compounds if we developed the methods? Contact ACS Laboratory to start the conversation.