When it comes to personal care products, consumers are making it increasingly clear that sustainability and performance are equally important. One leading option that delivers in both areas is Brontide natural butylene glycol, a multifunctional ingredient for formulators who want to boost the performance of their products. A replacement for petroleum-based butylene glycol, Brontide natural butylene glycol is created through the fermentation of plant sugars rather than the conventional petrochemical process—which begins with acetaldehyde, a mutagen and carcinogen.

 
The Multifunctional Role of Butylene Glycol
 
Butylene glycol is an organic, colorless alcohol used in a broad range of personal care products as a humectant, an antimicrobial agent and a solvent. As a multifunctional ingredient, butylene glycol is a key component of various personal care products and cosmetics in the market today, including serums, masks, cleansers, scrubs and lotions.

 
Design of the Study
 
To further explore the benefits of Brontide natural butylene glycol in personal care products, Genomatica commissioned Here2Grow—a British research and development firm named Cosmetics Development Specialist of the Year UK 2021, as part of the Innovation and Excellence Awards, presented by Corporate LiveWire—to conduct a study on natural solvent performance in hand creams to substantiate the impact a multifunctional natural solvent can have in personal care products. Results from the October 2021 study indicated that Brontide natural butylene glycol delivered superior performance in nearly all 10 sensory attributes tested, including gloss, reduced stickiness, spreadability and after-feel, compared to other natural glycols.
 
The Here2Grow study used a panel of 28 consumers who were trained prior to testing to identify sensory attributes. Participants were asked to perform a home-user sensory evaluation with an emphasis on product nuances, ranging from appearance to rheology and skin feel. Panelists were then asked to rank three hand cream formulations that were identical except for a single ingredient. That variable—a chemical compound containing multiple hydroxyl groups, known as a diol—was one of three naturally derived diols commonly used in skin care products: Genomatica’s plant-based Brontide natural butylene glycol along with longstanding natural ingredients, glycerine and propanediol. These diol compounds are similar at the molecular level, yet their small molecular variances can result in noticeable differences in finished skin care formulations.
 
To determine the characteristics a particular diol contributes to a formulation, a basic oil-in-water hand cream was developed. The three diols were prepared in identical formulations at a concentration of 3%. The remaining ingredients in the test hand cream were aqua, coco-caprylate/caprate, guar gum, parfum, sunflower seed oil, squalene, potassium sorbate, avocado oil, tocopherol, sodium benzoate, phenoxyethanol and glyceryl stearate.          
                        
The research team developed a set of 10 sensorial attributes on which each formulation would be evaluated. These parameters were selected for their critical value in determining the effectiveness of a hand cream and identifying the areas where a multifunctional diol solvent can influence the consumer experience. Each dimension was evaluated on a scale of one to nine.
 

The 28 participants were able to recognize these sensory attributes, emphasizing sensitivity to the nuances in the different product attributes. Study participants were given the three hand cream samples to apply to their skin and were asked to evaluate each sample formulation on 10 sensorial parameters. Scores from the participants were tallied and averaged to determine similarities and differences in sensorial perception and performance.

 
Study Results 
 
In eight of the 10 tested parameters, Brontide natural butylene glycol was perceived to be as good as or better than the glycerine and propanediol alternatives. 
 


Brontide natural butylene glycol achieved superior performance scores in the positive attribute categories of gloss/shine, spreadability and slipperiness. It was also considered the least sticky and greasy in the negative attribute categories, with similar residue compared to glycerine and propanediol.
 


In addition, the sample containing Brontide natural butylene glycol was perceived to deliver comparable performance in rub-out, after-feel and residue, when compared with the samples containing glycerine or propanediol. 
 
Appearance/integrity of shape was the one area where Brontide natural butylene glycol did not outperform the competing formulations, a situation that would potentially be overcome by including waxes or other rheology modifiers. 
 
Absorbency, the number of rubs at which the product loses its wetness, moist feel and a resistance is perceived, was also evaluated. The three solvents performed comparably within five rubs of each other with glycerine requiring the most rubs (62 on average), Brontide natural butylene glycol requiring 61 rubs and propanediol needing 56 rubs to completely absorb the formulation into the skin.


 
Sensory Benefits 
 
The Here2Grow study verifies that panelists find Brontide natural butylene glycol better than or equal to the natural diols against which it was tested, in most of the key categories of interest. In all, the study produced a total of 840 data points, providing personal care formulators and marketers with insights on the best ingredient choice for achieving desired performance benefits in hand creams.  
 
A natural ingredient under the ISO 16128 definition, Brontide natural butylene glycol offers formulators a pathway to achieving corporate sustainability goals. In winning the prestigious 2020 Green Chemistry Challenge Award given by the U.S. Environmental Protection Agency, Genomatica bolstered its credentials as a leader in delivering sustainable products made by and for the planet. 

 
A Sustainable Solution
 
According to Genomatica’s peer-reviewed Brontide life cycle assessment (LCA) ISO:14040:2006, Brontide natural butylene glycol can slash greenhouse gas emissions by about 51 percent compared to conventional production. 
 
Genomatica’s Brontide natural butylene glycol reduces global greenhouse gases by 1.92 kg CO2 per kilogram compared to conventional production. This means the ingredient has the potential to reduce global greenhouse gases by nearly 100,000 tons of carbon dioxide equivalent (CO2e) per year and eliminate the use of 50,000 tons of acetaldehyde, a carcinogenic and mutagenic ingredient used in conventional production methods.

 
Conclusion
 
The results of the Here2Grow study found that Brontide natural butylene glycol provides superior or comparable performance in nearly all sensorial dimensions tested when compared to widely used natural solvents, glycerine and propanediol.  
 
As consumers increasingly demand more sustainable products, Brontide natural butylene glycol can provide reliable metrics that can help personal care brands communicate transparently to consumers. 
 
For more information about this study and Brontide natural butylene glycol, contact Kyle Huston, product marketing manager, Genomatica at +1 832-562-1536 or [email protected]. To request a sample, click here.