Extraction of DNA from leather and applications to the supply chain

Many articles that are sold as 'genuine' chamois leathers do not legally meet the requirements of this definition. There are USA and British Standards that detail what can be described as genuine chamois (along with specifications in other countries). This limits the type of material that can be used for chamois production and also the type of tannage. The authenticity testing of chamois leather is complicated. The most technically challenging element has been proving the origin of the species. This is because chamois leather does not have the grain layer present which would facilitate species diagnosis by microscopy. A technique has been developed that allows the extraction and amplification of DNA in leather samples to provide unequivocal species identification. This is an exciting development for the leather industry, using state of the art genetic testing procedures and could offer scope with outer authenticity issues including trading standards and protected species. This technique is also of value with regards to identification of animal origin. This for example would assist with ensuring that material sold as being from a particular region was genuine. The definition of chamois leather also relates to the type of tannage (which must be of an oil type). Aldehyde tanning followed by marine oil fatliquoring does not meet the British Standard classification of chamois leather (In the USA the leathers must be solely oil tanned). It is known that the mechanism of oil tanning is through cross-linking of acrolein and peroxides liberated during the auto oxidation of the marine oil, with the lysine residues on the collagen. This cross-link is very stable to acid digestion. Research has determined that it is possible to determine whether leather has been subjected to a full oil tannage through analysis of the concentration of lysine released after acid hydrolysis. Genuine chamois leather exhibits lower levels of free lysines. This analysis along with quantification of the level of formaldehyde provides a suite of tests that can be used to authenticate chamois.