Abstract

The assessment of the total proteolytic activity in enzymatic preparations through the use of soluble substrates, such as casein (FuldGross and Lohlein Volhard methods), as well as the correlation of such activity with the behavior of such preparations on the skin substrate, are topics that have been discussed and debated repeatedly. The disadvantage in these test substrates is that the correlation between the testing data and the effect upon the hide components is often inadequate.

Since chromogenic substrates such as azo-albumin, hide powder azure and keratin azure are representa tive of the various hide components, they allow for the performance of assessments that are closer to the conditions involved in leather manufacturing. Using these substrates, the curve of enzymatic activity in terms of pH can be obtained in a relatively easy way, providing guidance, in the appropriate use of the enzymatic products.

This report provides the results obtained in the assessment of proteolytic activity through the use of hide powder azure (partially denaturalized collagen) for different commercial enzymatic products. The products were selected considering the need to evaluate preparations for the soaking, unhairing and bating processes. A comparison between the analytical results and the behavior of the enzymatic products in tanneries was also carried out.

The use of hide powder azure allows us to gain better knowledge on enzymatic preparations than that obtained from an isolated value of proteolytic activity assessed by the Fuld—Gross and Löhlein—Volhard methods, especially when the goal is an analytical tool for predicting the behavior of enzymes upon the skin during the various manufacturing processes and thus making an appropriate product selection.