Hana Chi1, Zouhair Ammar Katranji1, Carly Musleh1, and Amanda Solaiman1
1 – School of Pharmacy and Pharmaceutical Sciences, Faculty of Health Sciences and Wellbeing, University of Sunderland, Sunderland SR1 3SD, UK
Background: The increasing interest in hair-repairing qualities of peptides, has led to a growing demand for these products to be on the market and a rise in preference for natural and sustainable alternatives. This study investigates the impact of an optimized conditioner formulation containing 2% Lupine peptide, an eco-friendly vegetable-sourced hydrolysed protein, on bleached hair. The performance and efficacy were compared against a base conditioner (without peptides), an industry-leading hair treatment, and untreated hair samples.
Methodology: The effects of the different formulations on the physical and mechanical properties of the hair were evaluated through hair tensile strength testing using the MTT690, where 30 hair fibers were randomly selected from each treated tress and mounted between two brass crimps. Scanning Electron Microscopy (SEM) was used to investigate the morphology of the hair cuticles, and Fourier Transform Infrared (FTIR) analysis to identify composition of treated hair and investigate any changes to the hair samples.
Results: Hair samples treated with lupine peptide-based conditioner showed a significantly improved tensile strength of 178.96 MPa, compared to untreated samples (163.31 MPa, p = 0.014) and samples treated with base conditioner only (161.87 MPa, p = 0.017). The tensile strength of the hair tresses conditioned with the industry-leading product was slightly lower (170.50 MPa), with statistical analysis revealing that the lupine peptide-based formulation performed on par with this conditioner (p > 0.05). Minimal differences in break strain were observed among the formulations, with untreated, base conditioner, Lupine peptide and the industry-leading hair treatment achieving 48.97%, 49.99%, 49.71% and 49.23% respectively (p > 0.05). Partial cuticle repair can be seen through SEM imaging after application of the lupine peptide-based conditioner, which shows smoother and more uniform overlapping of the cuticle scales. While little impact on the restoration of disulphide bonds can be seen through FTIR testing, the findings in this study suggest that Lupine peptides can improve tensile strength and the overall appearance of the hair.
Conclusion: Findings of this study show promising results, with significant hair strengthening properties of the formulated lupine-based conditioner. The low molecular weight of these peptides could be responsible for the enhanced penetration into the hair cortex, thereby facilitating repair and protection of the hair cuticle.
