O o d h e a d p u b L i s h I n g L i m I t e d

14.3
Extraction of keratin from wool for new
product development
Advanced applications of wool beyond the fibre utilise the keratin protein
from which the fibre is constructed. The first step, then, in development of
these materials is isolation of that protein in a versatile form that can be
further manipulated into the desired application. Wool, by its nature, is a
tough insoluble material evolved by nature to be robust and resistant to
degradation. Its conversion to a state where it can be widely manipulated is
not straightforward and this has been a key reason that keratin protein has
not been commercially exploited as a material in the way that other biopolymers
have been, such as collagens, alginates, celluloses and starches. The simplest
way to isolate a soluble from of keratin from the source fibre is to apply
conventional methods of hydrolysis, using acid, alkali or enzymatic digestion
of the peptide bonds to create a mixture of peptides and amino acids that
have retained none of the secondary or tertiary structure of the core protein.
In most cases these processes also destroy many of the core amino acids.
Although this harsh processing destroys many of the unique characteristics
of the protein, it has provided a route for several developments, such as the
historic industrial uses explored below.
In order to progress beyond these limited applications of keratin-derived
peptides, hydrolysates and amino acids, a series of processes for the isolation
of keratin proteins from wool that maintain core features of the protein and
its structure have been developed (Smith et al., 1997; Kelly et al., 2002).
Most of the processes do not hydrolyse the peptide linkages and this allows
the keratin proteins that are produced to retain a form and function similar to
the native keratins. By maintaining the structural and chemical complexity
of the native proteins, by having substantial fibrous proteins that naturally
form robust and ordered materials, and with chemically active amino acid
components such as cystine present in abundance, then advanced applications
in a range of areas can be developed. The development of the technology to
achieve these forms of keratin is key to the creation of advanced applications
of wool.
© 2009 Woodhead Publishing Limited

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Advances in wool technology
326