Thi Quynh Tien Pham 1, Carly Musleh, Paul Carter and Amanda Solaiman 1 *
1 – School of Cosmetic Science, University of Sunderland, Sunderland SR1 3SD, England
* Correspondence: Amanda.solaiman@sunderland.ac.uk
Background: Hair is an integral part of the body as it serves numerous functions. Among hair care products, shampoos play a critical role in cleansing and maintaining healthy hair. Sodium Laureth Sulfate (SLES) is a well-known surfactant that is very effective at removing dirt, but it can also strip the hair of its natural oils, resulting in scalp irritation and damage to the hair. There is a growing shift toward sulphate-free shampoo formulations, driven by consumer demand. This research aimed to develop and optimise two types of shampoos: one containing SLES and a sulfate-free variant containing Sodium Lauroyl Sarcosinate. The study assessed the effect of surfactant type on the shampoo’s performance and hair health. Additionally, hydrolysed lupine peptide, a bioactive ingredient known for its moisturising and strengthening properties, was incorporated into the SLES formulation to evaluate the potential benefits of enhancing hair strength and elasticity.
Methodology: The physicochemical tests consisted of sensory evaluation, pH measurement, foam volume, viscosity, and hair tensile strength measurements. These tests were conducted on three shampoo formulations: SLES, sulfate-free, and SLES incorporated with lupine. For sensory evaluation tests, odour, clarity, and colour were evaluated for all formulations. Foam volume was measured using a 1% shampoo solution using a cylinder shake method. Times were recorded at 30 seconds, 1 minute, 1 minute, and 30 seconds and 2 minutes. The viscosity of all shampoos was measured by using a Brookfield Viscometer, using the spindle T64 at different speeds. The pH was measured by using a HALO2 Wireless pH tester and recorded weekly.
Hair tresses were treated with three formulations and then measured by FDAS770 and MTT690 Dia-Stron instruments to assess the elasticity and strength after 1 and 3 cycle washes.
Results: All formulations showed similarities in terms of odour, clarity and foam volume. However, both the lupine peptide-based shampoo and the sulfate-free shampoo generated more lather compared to SLES. All formulations showed non-Newtonian shear thinning behavior. The pH of shampoo formulations was compatible with the skin’s pH, ranging from 5.5 to 5.89 with the purpose of maintaining the hair and the scalp healthy, and no significant change in pH after each week, indicating the stability of the formulations. Findings from hair tensile strength and elasticity indicate that the shampoo containing lupine and sulfate-free shampoo performed better than the traditional SLES formulation especially after 3 cycle washes (184.82, 174.0, and 170.33 MPa respectively).
Conclusion: Through all evaluations, SLES contributes essential properties for shampoo; however, the lupine shampoo and sulfate-free variant create a promising field for modern shampoo formulation in nourishing and maintaining healthy hair.
