Proteomic method for the identification and quantification of animal hair fibres

The market of high quality textiles requires suitable analytical methods for the determination of their fiber composition to guarantee that no falsification occurs, especially when cheaper fibers, like wool and yak, are blended with expensive fibers, like cashmere. The traditional microscopic techniques are subjective depending on the expertise of the operator and often are affected by chemical treatments to which the fibers have been submitted during textile processing. Several methods have been studied to improve the objectivity and accuracy of the results of the animal fiber blend identification, like methods based on the extraction and analysis of DNA (Tang et al., 2014) or based on specie-specific monoclonal antibodies (Tonetti et al., 2012). Nevertheless, the results obtained are often affected by chemical treatment such as bleaching, dyeing and depigmentation. The method based on electrospray (ESI) mass spectrometry (MS) combined with liquid chromatography (LC) follows a proteomic approach to assess molecular markers for species identification (Paolella et al., 2013). Keratin from sheep, cashmere goat and yak are similar but not identical, because in some specific parts there are amino acidic variants that can been used as specific peptide-marker to distinguish each animal fibers. Therefore, keratin proteins are extracted from fibers, digested by trypsin enzyme and the peptides released are analyzed with LC/ESI-MS, monitoring only the specific marker-peptides: their specificity have been also confirmed by the identification of amino acidic sequences by different LC-MS/MS analysis. Furthermore, these markers can be successful used not only for qualitative analysis of wool, cashmere and yak blends, but also for quantitative ones, with a limit of detection of 3%. The proteomic method was recently applied to other animal hair fibers, such as Camel, Lama, Alpaca, Vicuna and Guanaco, in order to identify new molecular markers to discriminate Camelidae from Bovidae. Preliminary results showed that there are specific molecular markers for Camelidae and for Bovidae, suitable both for qualitative and quantitative analysis. This proteomic method continues to prove to be an objective and accurate method for animal hair fibers analysis, unaffected by chemical treatment and applicable to sample from various stages of textile processing.