WS-23: Composition, Cooling Action, and Health Aspects

WS-23 is a synthetic cooling agent widely used in food, beverages, and personal care products. Unlike menthol, which provides both a cooling sensation and a minty flavor, WS-23 delivers a clean, intense cooling effect without significantly altering taste. This makes it ideal for applications requiring a strong yet neutral cooling experience.

Its growing use has raised questions about its mechanism of action, applications, and potential health effects. Understanding how WS-23 interacts with sensory receptors and how the body processes it offers insight into its safety and effectiveness.

Chemical Composition And Properties

WS-23, chemically known as N,2,3-Trimethyl-2-isopropylbutanamide, belongs to the class of synthetic cooling agents called alkyl amides. Its structure consists of a branched aliphatic chain with an amide functional group, which contributes to its cooling effect. Unlike menthol, which contains a hydroxyl group responsible for its minty aroma, WS-23 is nearly odorless and tasteless. This allows it to provide cooling without adding flavor, making it highly versatile.

WS-23 appears as a white crystalline powder with a melting point between 58°C and 61°C. It is sparingly soluble in water but dissolves readily in ethanol, propylene glycol, and other organic solvents. This solubility makes it suitable for both aqueous and oil-based formulations. Its stability under different pH conditions and resistance to thermal degradation enhance its usability in food, beverages, and cosmetics, ensuring consistency in sensory experience.

WS-23 is highly potent at low concentrations. Effective cooling sensations occur at as little as 10–50 ppm in beverages and 30–100 ppm in confectionery products. Its ability to activate cold-sensitive receptors without requiring high dosages makes it efficient. Unlike menthol, which can introduce bitterness or an overpowering minty taste at higher concentrations, WS-23 maintains a clean cooling effect even at elevated levels.

Mechanism Of Cooling Sensation

WS-23 induces a cooling sensation by interacting with the body’s thermosensory system, specifically targeting receptors that detect temperature changes. Unlike menthol, which activates transient receptor potential melastatin 8 (TRPM8) channels in a way that mimics cold exposure, WS-23 enhances the perception of coolness without producing tingling or burning. This results in a smoother, more evenly distributed cooling effect.

The TRPM8 receptor, responsible for detecting temperatures between 8°C and 28°C, triggers calcium and sodium ion influx when activated, sending cooling signals to the brain. While menthol binds to TRPM8 directly and prolongs activation, WS-23 acts in a way that leads to a rapid-onset cooling effect that peaks quickly and dissipates more uniformly.

Unlike menthol, which concentrates its effect on specific contact points, WS-23 produces a more diffuse cooling experience. Its lower lipophilicity reduces accumulation in lipid-rich tissues, allowing for a balanced cooling effect, particularly in mucosal applications like beverages and oral care products.

WS-23 may also influence other thermosensitive pathways. Some studies suggest it interacts with mechanosensitive ion channels, enhancing the perception of coolness without affecting taste. This makes it advantageous in formulations requiring cooling without altering flavor.

Sensory Receptor Interactions

WS-23 exerts its cooling effect by targeting transient receptor potential (TRP) channels involved in thermosensation, primarily TRPM8. This ion channel, expressed in peripheral sensory neurons, responds to temperature drops and chemical stimuli by allowing calcium and sodium ions to flow into the cell, initiating a neural signal interpreted as cold.

WS-23 activates TRPM8 in a way that favors rapid but controlled receptor stimulation. Unlike menthol, which embeds into cell membranes and prolongs its effect, WS-23 is less prone to bioaccumulation in lipid-rich tissues. This allows for an immediate cooling sensation that does not linger excessively. Research suggests WS-23 interacts with the extracellular domain of TRPM8, initiating ion flux without causing desensitization, a common issue with prolonged menthol exposure.

Beyond TRPM8, WS-23 may also influence mechanosensitive ion channels that detect touch and pressure, contributing to its smooth, even cooling distribution. This is particularly relevant in oral applications, where an inconsistent cooling effect can lead to an uneven sensory experience. By targeting multiple receptor types, WS-23 achieves a balanced cooling profile that enhances overall mouthfeel.

Usage In Confectionery And Beverages

WS-23 is increasingly used in confectionery and beverages for its intense cooling effect without altering taste. Unlike menthol, which introduces a minty note, WS-23 provides a purely thermal cooling sensation, making it ideal for fruit-flavored candies, chewing gum, and carbonated drinks.

In confectionery, WS-23 is used at concentrations between 30 and 100 ppm. Its solubility in ethanol and propylene glycol ensures even distribution in both hard and soft candies. It enhances the sensory appeal of tropical and citrus-flavored sweets, mimicking the freshness of chilled fruit. In sugar-free formulations, WS-23 offsets the warming sensation of high-intensity sweeteners like sucralose and aspartame, creating a more balanced taste experience.

In beverages, WS-23 is used at levels between 10 and 50 ppm, providing a crisp cooling effect in carbonated soft drinks, energy drinks, and flavored waters. Its ability to enhance refreshment without affecting base flavor makes it a preferred choice for summer products. In dairy and plant-based beverages, WS-23 replicates the cooling sensation of traditional chilled drinks, even at room temperature. This improves palatability in protein shakes and meal replacement beverages by counteracting thick mouthfeel.

Role In Personal Care Formulations

WS-23 is widely used in personal care products for its controlled cooling effect without the scent or irritation associated with menthol. This makes it valuable in skincare, oral hygiene, and shaving formulations. Its stability in emulsions and compatibility with various cosmetic ingredients allow seamless integration into lotions, serums, and cleansing products.

In skincare, WS-23 is found in after-sun gels, facial mists, and body lotions for its soothing effect. Unlike menthol, which can cause redness or discomfort in sensitive individuals, WS-23 delivers a milder cooling sensation without triggering vasodilation or excessive tingling. This makes it ideal for products aimed at reactive or easily irritated skin.

Oral care products, including toothpaste and mouthwash, also benefit from WS-23’s cooling properties. While menthol is traditionally used, its strong taste can overpower other flavors. WS-23 provides a fresh sensation without altering taste profiles, making it suitable for formulations incorporating fruit or herbal flavors. Its cooling effect enhances the perception of cleanliness in breath-freshening products without the burning sensation associated with high menthol or alcohol concentrations.

Biological Breakdown Pathways

Once absorbed, WS-23 undergoes metabolic processing in the liver, where enzymatic reactions modify its structure for excretion. These pathways prevent accumulation in tissues, reducing prolonged exposure risks.

WS-23 primarily breaks down through hydrolysis of the amide bond, yielding smaller, water-soluble fragments excreted via the kidneys. Enzymes such as amidases and cytochrome P450 oxidases facilitate this process, converting WS-23 into metabolites efficiently removed through urine. Studies on similar compounds suggest WS-23 follows first-order kinetics, meaning its elimination rate is proportional to its bloodstream concentration. This predictability supports its safety profile, as it does not bioaccumulate.

In topical applications, WS-23’s absorption through the skin is minimal, with most of the compound remaining on the surface before being washed away or naturally degrading. When ingested, its metabolic fate aligns with other small amides, undergoing enzymatic cleavage before systemic distribution. The absence of persistent metabolites or toxic byproducts further supports its use in consumer products, with regulatory assessments finding no significant long-term safety concerns.