Chemical and physical properties of pigmented and non‐pigmented hair (‘grey hair’)

Analysis of structural changes in bleached keratin fibers (black and white human hair) using Raman spectroscopy

“…The 1/2-cystine content of virgin black human hair (Sample 3) was slightly higher compared with that of virgin white human hair (Sample 1), while the cysteic acid content of Sample 3 was slightly lower compared with that of Sample 1. This result was in agreement with Hollfelder et al's 25 opinion. Also, the 1/2-cystine contents of both black and white virgin human hair (Samples 1 and 3) decreased, while the cysteic acid content increased by performing the bleaching treatment.…”

“…Similarly, as in the case of the Raman spectra of the virgin and bleached white human hair, the Raman spectra of the bleached black human hair had a good S/N ratio, due to it not being influenced by fluorescence. Hollfelder et al 25 reported that the amino acid composition of pigmented and nonpigmented fibers is quite similar except for a slightly higher content of cysteic acid and lower 1/2-cystine content in nonpigmented hair. Assuming that the -SScontent of the virgin black human hair is equal to that of the virgin white human hair, the S-S band intensity of the bleached black human hair decreased remarkably, while the S-O band intensity increased significantly compared with that of the bleached white human hair.…”

“…24 The chemical and physical properties of white human hair are for the most part identical to those of other colors of hair except for the absence of melanin granules. 25,26 There are no statistically significant differences in terms of central maximum diameter, central cross-sectional area, central ellipticity, average tensile strength, average extent of transverse swelling, or the penetration of Orange II between black and white human hair. Also, Hollfelder et al 25 reported that the amino acid composition of pigmented and nonpigmented fibers is quite similar except for a slightly higher content of cysteic acid and lower 1/2-cystine content in nonpigmented hair.…”

“…25,26 There are no statistically significant differences in terms of central maximum diameter, central cross-sectional area, central ellipticity, average tensile strength, average extent of transverse swelling, or the penetration of Orange II between black and white human hair. Also, Hollfelder et al 25 reported that the amino acid composition of pigmented and nonpigmented fibers is quite similar except for a slightly higher content of cysteic acid and lower 1/2-cystine content in nonpigmented hair. On the other hand, after performing UV-irradiation, tensile strength and 1/2-cystine content of nonpigmented hair decreased compared with pigmented hair.…”

Protein structural changes in keratin fibers induced by chemical modification using 2‐iminothiolane hydrochloride: A Raman spectroscopic investigation

“…Furthermore, the chemical and physical properties of white human hair are for the most part identical to that of other colors of hair except for the absence of melanin granules. 27,28 Second, white hair bundles were used to avoid the destruction of the sample due to laser exposure. Third, it was confirmed beforehand that virgin white Chinese hair has uniform characteristics, regardless of the sample, which is not damaged by investigating the penetration of the reducing agent into the human hair with an optical microscope.…”