Enzymes are used throughout leather processing to refine fibre structure, improve softness, assist in degreasing, and enhance cleanliness and handle. However, one persistent challenge has limited our ability to compare enzyme performance across suppliers and process environments:
There is no universal unit for enzyme activity in leather processing.
Each supplier reports enzyme strength using its own proprietary unit system (e.g., AU/g, PU/mL, FPU/g, AGU, HUT). These measures are not directly comparable. As a result:
- Product selection relies heavily on experience rather than data.
- Process optimisation is supplier specific.
- Cost-performance decisions are rarely evidence-based.
- Research findings cannot be easily translated across tanneries.
This fragmentation obscures real performance differences and slows scientific and commercial progress.
Universal Activity Conversion via Calibration Curves
LASRA has developed a modular calibration framework that converts proprietary supplier units into Universal Activity Units (U) or katal based on reference assay calibration.
This allows any enzyme from any supplier to be expressed on the same quantitative scale.
We perform paired measurements:
| Supplier Unit (e.g. AU/g) | Reference Unit (U) |
| 12.1 | 9.7 |
| 23.4 | 18.5 |
| 47.2 | 36.2 |
A linear regression defines the relationship:
Once calibrated, any proprietary activity value can be converted directly to Universal Activity. To make the framework accessible to researchers and industrial technologists, LASRA built a clean, browser-based interface to carry out functions, including:
- Apply calibrations
- Calculate specific activity
- Visualise and export calibration curves
This enables universal data comparability without changing lab assays.
Why This Matters
| Impact Area | Benefit |
| Supplier Comparison | Enables evidence-based product selection |
| Process Efficiency | Identify activity-cost sweet spots |
| Technology Transfer | Trials are comparable across tanneries and regions |
| Research | Experimental results become reproducible and universal |
| Sustainability | Reduces overdosing, lowers effluent load |
This is one of the first open, systematic attempts to standardise enzyme activity reporting in leather manufacturing.
What Comes Next:
- Building shared calibration libraries among industry partners
- Supporting collagenase and keratinase systems used in bating and wool processing
- Publishing a validation dataset to support regulatory and peer review
- Integrating with hyperspectral + proteomic traceability pipelines