RELATIONSHIPS BETWEEN PROCESSING CONDITIONS AND STARCH AND PROTEIN MODIFICATIONS DURING EXTRUSION-COOKING OF PEA FLOUR

Pea flour was extruded under various conditions; extrusion treatment w as characterised by specific mechanical energy (SME), moisture content , shear rate at the die and product temperature. Product transformatio n was measured by starch solubility, protein solubility in specific bu ffers and by immunoassay with anti-legumin antibodies. Response surfac es showed that SME influenced starch and protein solubility more than did temperature. Decrease of protein solubility was attributed to form ation of non-covalent bonds and disulphide bonds which could partly ta ke place at the die, according to flow conditions. The most severe ext rusion conditions (SME > 250 kWh t(-1)) led to the creation of other c ovalent bonds. Immunoassay proved an efficient method for assessing th e severity of treatment by following the loss of legumin antigenicity.