A comprehensive study, “Beyond Sulfate-Free Personal Cleansing Technology,” published this week in the scientific journal Cosmetics, shed light on advancements in sulfate-free cleansing products.
Authored by Evelyn Su of Sino Lion USA and Stephen Herman of the University of Cincinnati, the research, which received no external funding, delved into the limitations of traditional sulfate-based surfactants and the promise of amino acid-based alternatives.
The growing demand for sulfate-free products
The study is grounded in the rapidly growing consumer demand for sulfate-free formulations, aligning with broader sustainability and safety trends. The authors emphasized that “the objective of sulfate-free personal cleansing technology should not be aimed solely at the absence of ‘sulfate’ wording in the list of ingredients, but on the true benefits both in personal use and in environmental effects.”
These benefits include mildness, biodegradability, low carbon and water footprints, and renewability.
According to the study, sulfates like sodium lauryl sulfate (SLS) and sodium laureth sulfate (SLES) have been mainstays in personal care formulations due to their cost-effectiveness and performance in foam production. However, these surfactants carry significant drawbacks.
The researchers explained that “sulfates can excessively strip oil from the skin, scalp, and hair, breaking barrier integrity and increasing trans-epidermal water loss.” Furthermore, the manufacturing of SLES often results in contamination with 1,4-dioxane, a carcinogenic byproduct.
Advantages of amino acid-based surfactants
The study positioned amino acid-based surfactants, particularly glutamates and alaninates, as the next generation of safe and sustainable cleansing ingredients. “Of the possible amino acid-based surfactants, glutamates for skin cleansing and alaninates for hair cleansing are the best alternatives both for performance and commercial viability,” the authors noted.
These surfactants offer intrinsic safety, are biodegradable, and align with increasing consumer scrutiny of ingredient sourcing.
Additionally, the researchers outlined technical advancements in addressing formulation challenges with glutamates, such as achieving the desired viscosity without sacrificing performance.
“The glutamates’ difficulty in thickening is due to their large, multicharged head group,” the authors wrote. Further, they noted that “patented technologies now enable blending glutamate surfactants with amphoterics to overcome this challenge, ensuring consistent viscosity across formulations.”
Safety and mildness: Key selling points
The study emphasized the mildness and safety of glutamate and alaninate surfactants compared to traditional sulfates. Using MTT50 and red blood cell tests, the researchers demonstrated that sodium cocoyl glutamate and alaninate outperform sulfates like SLES in safety and irritation potential.
“Sodium cocoyl glutamate has the highest MTT50 value among the surfactants tested, indicating superior mildness,” researchers reported, adding that “in contrast, SLES demonstrated the lowest safety metrics.”
Furthermore, glutamates contribute to reducing irritation and residue left by other surfactants. The study revealed that “the addition of 2.5% sodium cocoyl glutamate to a conventional SLES-based formulation resulted in a 55% decrease in SLES adsorption on the skin, improving mildness and skin feel.”
Environmental and market implications
Researchers also highlighted the environmental benefits of transitioning to amino acid-based surfactants. These surfactants, derived from renewable sources, offer lower water and carbon footprints compared to their sulfate-based counterparts.
The study further underscored broader market implications: “Sulfate-free products have demonstrated an annual growth rate of approximately 18% since 2010, driven by consumer demand for safer, sustainable, and ‘free-from’ formulations.”
The study provides a robust foundation for cosmetic and personal care manufacturers to reimagine their formulations. By integrating amino acid-based surfactants such as glutamates and alaninates, companies can deliver on consumer demands for safety, sustainability, and performance.
As the authors concluded, “The quest for better cleansing products thus promises a greener Earth for future generations.”
Journal: Cosmetics, 2025, 12, 14. Doi: 10.3390/cosmetics12010014, “Beyond Sulfate-Free Personal Cleansing Technology.” Authors: Su, E.; Herman, S.
