Raman spectroscopy and scanning electron microscopy application for physical characterization of horsehairs

Abstract

Horsehairs present several common characteristics in their chemical composition and molecular structure. The present study aims to analyze the physical characteristics of horsehairs belonging to different breeds. Morphological analysis of the horsehair fibers was performed using Scanning Electron Microscopy (SEM) and molecular structural characterization using the Raman Spectroscopy (RS) technique. Horse hairs were collected from three different horse groups (group A: mixed-breed; group B: Italian saddle; group C: thoroughbred). Each group was constituted of five horses with a mean body weight of 475 ± 25 kg, aged between 12 and 15 years old. SEM images showed differences in the surface layer (cuticula) and diameter size of horsehairs referred to different breeds. The investigation conducted through RS showed differences in the S – O band, located at 1044 cm−1, where cysteic acid is one of the amino acid constituents of α-keratin; in CH2 bending mode and CH stretching, located at ~1450 cm-1 and ~2900 cm-1, respectively. These differences could be attributed to genetic predisposition or metabolism; they could represent the real differentiation among the breeds, detectable by using RS.