A Standardized In Vitro Framework for Evaluating Hair Care Products: Hair Parameters and Efficacy Performance

BACKGROUND: There is an increasing demand for scientifically consistent methodologies to support the assessment of multifunctional cosmetic hair care claims while minimizing variability associated with in vitro testing. Therefore, the primary objective of this study was to develop a preliminary standardized in vitro human hair-tress-based framework for the comparative assessment of multiple cosmetic hair performance parameters under controlled laboratory conditions. MATERIALS AND METHODS: This was a controlled in vitro standardization study conducted on standardized human hair tresses. Hair samples were randomly allocated into test and control groups. A structured damage-induction protocol was implemented to simulate real-world hair exposure, including chemical damage (surfactant washes), thermal damage (high-temperature styling), photodamage (ultraviolet A exposure), and environmental damage (pollution-related stress via ambient air exposure). Multiple evaluation methodologies were applied and standardized to assess hair sensory parameters, hair breakage, tensile strength, split-end repair/reduction, hair shine, hair volume, color retention, moisture retention, frizz control, and microscopic evaluation of hair shaft parameters. All assessments were performed using instrumental, image-based, and sensory techniques under controlled laboratory conditions. RESULTS: Application of the test product to standardized hair tresses resulted in measurable changes across several evaluated hair parameters, showing improvement in hair breakage count by 21.00 ± 6.07 counts, hair tensile strength by 25437.01 ± 6169.93 gm/cm², hair shine by 2.15 ± 0.30, hair volume by 499.66 ± 34.30 cm², and reduction in hair frizziness by 89.20 ± 5.93 cm². In contrast, the control group did not demonstrate any notable improvement in the assessed parameters following the application procedure. Hair breakage increased to 51.50 ± 10.95, hair tensile strength slightly decreased to 23468.01 ± 7519.68, hair shine reduced to 1.40 ± 0.17, hair volume was reduced to 423.16 ± 15.81, and hair frizziness increased to 133.62 ± 8.56. CONCLUSIONS: The present study proposes a preliminary integrated in vitro hair-tress-based framework for evaluating the multifunctional performance of cosmetic hair under controlled laboratory conditions. The methodology demonstrated measurable changes in multiple hair parameters following product application, supporting its potential utility for comparative cosmetic hair assessment and claim support.