Overview
EN ISO 14902:2001 (ISO 14902:2001) specifies a laboratory method for the determination of trypsin inhibitor activity (TIA) in soya products used as animal feeding stuffs. TIA is used as an indicator of the degree of toasting/heat treatment of soy ingredients and affects protein digestibility in animal feeds. The method extracts inhibitors at pH 9.5, uses benzoyl-L-arginine-p-nitroanilide (L‑BAPA) as substrate, and measures released p‑nitroaniline spectrometrically (410 nm). The detection limit of the method is 0.5 mg/g.
Key Topics
- Scope and purpose
- Quantitative determination of TIA in soya products to assess processing quality and potential antinutritional effects.
- Analytical principle
- Extraction of trypsin inhibitors → inhibition of bovine trypsin → hydrolysis of L‑BAPA → spectrometric measurement of p‑nitroaniline.
- Sample preparation and extraction
- Grinding to minimize heat, extraction at alkaline pH (pH 9.5 ± 0.1), refrigerated extraction overnight (15–24 h).
- Reagents and equipment
- Use of analytical-grade reagents (Tris buffer, CaCl2, L‑BAPA, bovine trypsin), spectrometer at 410 nm, controlled water bath (≈37 °C), centrifuge (≈1 500 g), 10 mm cuvettes.
- Quality controls
- Check trypsin activity of each batch; use blanks and standards; aim for inhibition results in the 40–60% range via appropriate dilutions.
- Performance characteristics
- The standard includes guidance on repeatability, reproducibility and interlaboratory results.
Applications and Users
- Who uses EN ISO 14902
- Feed testing laboratories, soy meal and textured soy protein manufacturers, animal nutritionists, quality assurance teams in feed mills, regulatory authorities.
- Practical uses
- Verify processing adequacy (toasting) of soya products.
- Assess antinutritional factor levels impacting protein digestibility in livestock diets.
- Support product specification, batch release, supplier verification and compliance testing.
Related Standards
- ISO 3696 - Water for analytical laboratory use (referenced for reagent water quality).
- ISO 6497 - Recommended sampling methods for animal feeding stuffs (sampling guidance referenced but not part of the method).
By following EN ISO 14902:2001, laboratories can generate reproducible TIA data to support feed safety, nutritional formulation and process control for soya-based animal feed ingredients.