Quantitative Determination of Trypsin Inhibitory Activity in Complex Matrices

A quantitative assay using azocasein was developed to measure trypsin inhibitory activity in emulsions and other complex systems that are refractory to analysis. The method was tested for reproducibility on pure protein solutions as well as protein-containing material rich in fats and sugars, with special attention to emulsions. In the clean situation, the overall relative standard deviation was less than 6% while for the more complex systems it was less than 16%. The proce- dure proved robust against deliberate variations of temperature, incubation time and substrate concentration.