The earliest example of enzymes being used to improve industrial practice comes from the leather industry.
To make leather soft, it has to be bated. This simply means removing some of the protein material from the leather fibres. If this is not done, leather hides can be as stiff as cardboard. While such leather may be perfect for the soles of shoes, it is of little use for anything else.
For hundreds of years up to the early part of the 20th century, leather was bated by smearing it with excrement. The Roman writer Pliny reported the use of pigeon droppings for this process more than 2,000 years ago. And more recently, dog excrement was used extensively. It is hard to imagine that people used to go around the streets collecting dog excrement, which was then rubbed into leather hides. Tanners worked the excrement into the skins by hand, by paddle, or by foot. It is ironic to think that the finest ladies and gentlemen of the time wore leather gloves made in this way.
Excrement is rich in bacteria that produce proteases capable of degrading part of the leather. However, this primitive process was very difficult to control and the enzymes could damage the leather, which is largely made of protein.
Thanks to the German scientist Otto Röhm, a standardised bate called Oropon was developed in 1908 and the foul practice of using excrement was replaced. Oropon was based on an extract from the pancreases of slaughtered animals containing the enzyme trypsin found in the digestive system.
Since then, all bates have been based on enzyme preparations. In the latter part of the 20th century, pancreatic trypsin was partially replaced by bacterial and fungal enzymes from Novozymes and other companies. It is also possible to combine pancreatic and microbial enzymes to obtain synergy effects for an excellent bate.
Apart from bating, Novozymes’ enzymes are now used in various other stages, including soaking, liming (dehairing) and degreasing. The old artisan craft of leathermaking is changing as modern biotechnology gives the tanner new enzymes to control the process precisely. Enzymes improve the physical properties of leather in ways which cannot be matched by traditional chemicals. And not only this, enzymes are a clean technology, especially when compared to the dirty old practice of bating with excrement.