Water A Fundamental Component of Human Hair

Fiber type Alpha- keratose Beta- keratose Gamma- keratose Total 

A modified version of this procedure has been described by Wolfram and MiUigan [118]. Their procedure involves esterificahon of the carboxyl groups that are beheved to reside primarily on the alpha-helical proteins and proteins of the hair surface. Esterificahon decreases the solubility of these proteins, allowing the nonesterified proteins (of the matrix) to be extracted more easily. The soluble fraction of this procedure is called gamma -keratose it resembles gamma-keratose but provides a higher yield. The insoluble residue exhibits birefringence and is called the alpha-beta -keratose fraction. 

Other fractionations of human hair have been reported by Andrews [119] and by Lustig et al. [120]. The former paper describes a hydrolytic separation and the latter a fractionation by sulfonation followed by reduction [18]. These procedures have not been pursued to a great extent because of the inherent amino acid degradation in the initial solublization reaction. 

Similarity, hair dried with heat exhibit a lower moisture content than hair dried at room temperature [124]. After heat-drying, hair absorbs moisture but does not return to the room temperature dried moisture level until it is either rewet with water or conditioned at a higher relative humidity. Thus, a hysteresis exists between heat-dried hair and room-temperature-dried hair similar to that from absorption versus desorption of moisture. 

Hysteresis phenomena in the water sorption by high polymers [125] and by other proteins such as wool fiber [125] and casein [126] have also been described. Smith [125] suggests that hysteresis is a result of differences in the ratio of bound to free water in the substrate, with a larger amount of bound water present on desorption than on absorption. 

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