Holistic Solutions for a Refreshing Beauty

With global warming a reality, temperatures are expected to rise over time. According to the Intergovernmental Panel on Climate Change, the average global temperature is estimated to increase by 1.5 degrees Celsius in the "first half of the 2030s". Consumers will feel warmer and will seek solutions that provide freshness. Menthol and menthol-derived products have always been highly valued ingredients in beauty routines because they aim to provide the skin with an instantly refreshed and energetic feeling. For this reason, we anticipate this market will continue to grow in regions around the world.

Neuro-Sensory Process

Despite its widespread use, the ability of menthol to activate cold-sensitive receptors was not discovered until relatively recently1. This receptor is called TRPM8. Activation by physical stimuli (cold) or chemical stimuli (such as menthol and its derivatives) produces an electrical signal transmitted to the brain through sensory neurons, resulting in the sensation of cooling (Figure 1). This process is therefore a neuro-sensory process. [caption id="attachment_157182" align="aligncenter"] Figure 1. Skin diagram showing how
freshness is perceived[/caption] The TRPM8 receptor is an ion channel belonging to the TRP (transient receptor potential) family. Different TRP receptors (TRPV1-4, TRPM8, TRPA1) have been identified in the skin that transmit temperature perception (thermal stimuli). The TRPM8 receptor is expressed in sensory neurons as well as in non-neuronal epithelial cells.

A Range of Solutions for Producing Freshness

Although menthol provides a very effective cooling sensation, it has numerous disadvantages. It carries a strong odor or taste, a burning sensation (generally not tolerated by sensitive skin), and high volatility. Due to these undesirable properties, its use in anti-ageing formulations where consumer tolerance is high and sensory aspects (pleasant odor) are very important is limited. For this reason, Symrise overcame these disadvantages by developing a range of cooling agents that have the same physiological mechanism of action as menthol but limit menthol's undesired effects and can create a sensation of freshness on the skin. Frescolat® ML series (INCI: Menthyl lactate) is a menthol derivative (menthol ester) that can create a mild and soft cooling sensation on the skin (Frescolat® ML is now widely used in many applications (rinse-off and leave-on). Well-tolerated and completely odorless in formulation, Frescolat® ML creates freshness in perfect harmony with the skin. A recent in vitro test showed that it helps protect against harmful bacterial growth in intimate areas. This series consists of 100% natural and Ecocert certified, natural (Frescolat® ML nat); colorless, solid (Frescolat® ML) and powdered crystal form (Frescolat® ML crystal new quality). This series enables all formulation needs and sustainability requirements to be met. Long-lasting cooling sensation is an important parameter for consumers. Frescolat® X-cool (INCI: Menthyl Ethylamido Oxalate) provides an "ice effect" that can appeal to consumers seeking greater sensory experience. In addition to its high efficacy profile, this ingredient is also easy to apply (viscous liquid product, colorless, odorless, with no color and odor effects in the finished product). Other cosmetic applications require content suitable for high pH; Frescolat® MGA (INCI: Menthone Glycerin Acetal) is a solution that adds freshness to alkaline formulations such as depilatory products and deodorants. It provides long-lasting cooling effect and serves as a soothing player in hair care products. To achieve a stronger cooling sensation, Frescolat® Plus (INCI: Menthol, Menthyl lactate), a mixture of menthol diastereoisomers and menthyl lactate, was developed. This ingredient creates a sensation like menthol, but without mint odor. The cooling effect of Frescolat® products was confirmed and quantified in an in vivo study using an expert panel of 12 subjects. Volunteers applied various emulsions containing Frescolat® to their faces (sequentially). For each emulsion tested, a time-intensity graph was obtained by evaluating the intensity of perceived cooling sensation on a scale between 0 (no cooling effect perceived) and 10 (very pronounced cooling effect). Measurements were recorded every minute for 30 minutes (Figure 2). [caption id="attachment_157188" align="aligncenter"] Figure 2. In vivo study evaluating
cooling intensity[/caption] The sensory profiles have a characteristic bell-curve shape; this shows that the cooling sensation caused by cooling agents gradually increases in the first minutes following application and then gradually decreases within less than 30 minutes for all Frescolat® components where Frescolat® is present. Frescolat® Plus showed the strongest and fastest intensity with a peak at 5 minutes. These time-intensity graphs also reveal that Frescolat® X-cool and Frescolat® MGA provide very intense and long-lasting cooling effect. The self-perception of this cooling sensation is also strongly associated with feeling healthy.

Freshness and Healthy Feeling (Wellness):
Frescolat® ML

Cooling helps regulate stress-related heat perception and restores a sense of comfort. Mintel predicts that the beauty industry will directly address this new consumer need with mood-enhancing products aimed at mental health and well-being2. Recent studies of Frescolat® ML use Neurosciences to demonstrate how the sensation of freshness can trigger positive emotions. Symrise developed the Gen-isys program in 2019. A Neuroscience program with an approach to increase the validity of consumer research by integrating multiple data collection methods: - Biometrics: Measurement of heart rate showing the body's relaxation/arousal state. - Neuroimaging: Use of electrodes to monitor the brain's electrical activity (EEG). - Open survey: A subjective method aimed at asking volunteers to consciously express their feelings through questionnaires. These methods allow us to assess subconscious and conscious emotions. The study was conducted on 35 Malaysian women aged 18 to 45. Each volunteer, as part of a rotation, tested two products on different days at similar times: an emulsion containing 0.8% Frescolat® ML and a placebo emulsion (half the group used placebo first, the other half used Frescolat® ML first). Product application lasted 20 minutes and results were obtained through software (brain imaging and biometric parameters), questionnaires were completed by volunteers and statistically analyzed. Heart rate was measured through a holder attached to the volunteers' fingers at the moment the placebo or Frescolat® ML emulsion was applied to the skin. The results showed that the product containing Frescolat® ML showed greater changes in heart rate and that arousal increased with the product (Figure 3). [caption id="attachment_157190" align="aligncenter"] Figure 3. Heart rate monitoring with 0.8% Frescolat® ML[/caption] [caption id="attachment_157192" align="aligncenter"] Figure 4. Heart rate monitoring with 0.8% Frescolat® ML[/caption] The product was then evaluated using the electrophysiological method. EEG electrodes (headphones with several electrodes recording brain activity) were placed on the volunteers' scalp. Left prefrontal brain activity measures positive emotions, while right prefrontal brain activity measures negative emotions. Sensors attached to the scalp measure energy and record it as waves representing different moods. Relaxation is measured from theta wave intensity toward the back of the head. Experimental results showed that the product containing the ingredient caused less relaxation in volunteers; this is associated with arousal and confirms the biometric results. The product was then evaluated using the electrophysiological method. EEG electrodes (headphones with several electrodes recording brain activity) were placed on the volunteers' scalp. Left prefrontal brain activity measures positive emotions, while right prefrontal brain activity measures negative emotions. Sensors attached to the scalp measure energy and record it as waves representing different moods. Relaxation is measured from theta wave intensity toward the back of the head. Experimental results showed that the product containing the ingredient caused less relaxation in volunteers; this is associated with arousal and confirms the biometric results.

Retinol Tolerance Enhancer: Frescolat® ML

Retinol comes from vitamin A, a nutrient that helps direct cell cycles, increases collagen production, and reduces collagen breakdown. This ingredient is widely used in anti-ageing products and is estimated to grow at a compound annual growth rate (CAGR) of 3.8% from 2023 to 2030(3). Despite its high efficacy, this ingredient is also known to cause dryness, irritation, and burning sensation on the skin. To enable formulators to continue using this content without side effects, Symrise launched an in vivo test on 22 volunteers sensitive to retinol to assess whether the uncomfortable sensations caused by retinol could be reduced with Frescolat® ML as a tolerance enhancer. They evaluated these unpleasant sensations caused by retinol (burning, stinging, and warming) by comparing a formula containing both retinol and 1% Frescolat® ML with one containing only retinol. The results show that the formula containing Frescolat® ML significantly and immediately soothes the uncomfortable sensations caused by retinol. [caption id="attachment_157194" align="aligncenter"] Figure 5. Reduced retinol discomfort sensation with 1% Frescolat® ML[/caption]   References 1 McKemy et al., Identification of a cold receptor reveals a general role for TRP channels in thermosensation. Nature. 2002. 416 52-58 and Peier et al., A TRP channel that senses cold stimuli and menthol. Cell. 2002. 508:705-715 2 Mintel GNPD database: Beauty Spot: Beauty taps into the emotions, published in June 2018 3 Grand Review Report: Retinol Market Size, Share, Growth & Trends, 2023   Author Héloïse Bouchez Junior Global Product Manager Cosmetic Ingredients Division BU Actives & Botanicals Symrise S.A.S. Tuğba Bayazıt Technical Application Specialist Africa, Middle East, Turkey Laboratories Manager