THERMAL MODIFICATION OF SODIUM-CASEINATE .2. INFLUENCE OF TEMPERATUREAND PH ON NUTRITIVE PROPERTIES

Thermal modified Na-caseinate (90-degrees-C, 10 min at pH 3.0, 6.5 and 10.0) are digested during a physiological two-stage digestion (pepsin /trypsin-pancreatin) but also during a prolonged peptic proteolysis. N utritive availability was evaluated by comparison of proteolytic patte rns (FPLC, Superose 12) obtained with unmodified and modified Na-casei nates. These results were set in relation with micellar and methylated casein representing the genuine and the physiologically questionable form of this protein. It was found that with a two-stage digestion mos t effects of thermal modifications were equated. However, peptic prote olysis and undigested protein residues were found to be excellent indi cators of preliminary thermal treatments.