Mechanical Properties of Wet Blue Following Acid Bating Process Treated with Crude Enzyme from Rhizopus oligosporus

Enzyme is one of the ingredients used in several tanning processes such as bating. Bating is generally conducted under alkaline conditions, but it can also be carried out under acidic conditions. This study aimed to evaluate mechanical and physical properties of wet blue following bating conducted under acidic conditions treated with enzymes synthesized by R. oligosporus compared to those of the conventional process. This study was arranged on a completely randomized design with a single factor, i.e., five levels of enzyme activity (0, 2.5, 5, 7.5, and 10 U mL-1). The results showed that the use of enzymes from R. oligosporus influenced positively mechanical properties of the wet blue produced. Increasing levels of enzyme activity produced significantly higher tear strength and lower elongation at break values. No significant differences in tensile strength were observed following applications of both the synthesized and conventional enzymes. The synthesized enzyme was best applied at an activity level of 5 U mL-1 producing leather with good tear strength (55.40 ± 5.49 N mm-1) and elongation at break (45.63 ± 4.17 %) values, which were significantly different from those of 0 U mL-1, but not significantly different from those of 10 U mL-1 and the conventional process. Mechanical properties of the leather produced met the standard values for goat/ sheep leather jacket as specified in Indonesian National Standard (SNI) 4593:2011. The results suggest that the synthesized enzyme from R. oligosporus can potentially replace the conventional enzyme commonly used in the bating process.