Comparison of solubility of pea protein hydrolysate by three analytical methods

Pea protein hydrolysate was obtained by enzymatic hydrolysis with trypsin. The degree of hydrolysis (DH) was controlled by using the pH-stat method. Solubility of the trypsin-treated hydrolysate was tested at nine different pH values starting from 2 up to 10. Protein determinations were carried out using Kjeldahl, Lowry and modified Lowry methods. The results revealed that samples analysed with either the Kjeldahl or Lowry method gave similar values. However, systematic consistent differences existed for those results obtained by the Kjeldahl and the modified Lowry as well as between those results obtained by the Lowry and the modified Lowry.