Acknowledgements

The authors are grateful to Erin Lee for preparing the samples for mass spectrometry, Evelyne Maes for helpful comments during the preparation of the manuscript and Professor David Parry of Massey University for helpful discussions. The work was funded by the Wool Research Organisation of New Zealand (WRONZ) and the Ministry of Business Innovation and Employment through the New Materials from New Zealand Wool partnership program via Wool Industry Research Limited.