Changes in anti-nutrients, protein solubility, digestibility, and HCl-extractability of ash and phosphorus in vegetable peas as affected by cooking methods

The effects of microwave cooking, compared with other conventional processes (ordinary and pressure cooking), on phytic acid, tannins, trypsin inhibitor and lectin haemagglutinating activities in vegetable peas were investigated. Protein and amino acid solubilities (in water, saline and HCl solutions) and in vitro protein digestibility (IVPD), as well as HCl-extractable ash and phosphorus, were also studied. Cooking reduced phytic acid and tannin contents. Ordinary cooking, which took longer time, was most effective in reducing phytic acid (47.9%), while microwaving gave the greatest reduction (25.7%) in pea tannins. Trypsin inhibitor and lectins were readily removed by the studied methods. IVPD of raw peas was 73.5% and it was improved upon cooking. Pressure cooking resulted in most the improvement (6.43%). Solubilities of proteins and amino acids were greatly decreased (∼50%) by cooking due to thermal modification and loss of fractions soluble in cooking water. Moreover, HCl-extractable ash and phosphorus (as a measure of availability) were enhanced as cooking time increased. Pressure cooking showed the highest percentages of both extractable ash (94.93%) and phosphorus (4.36%).