Comparaison de trois méthodes pour la mesure du degré d'hydrolyse de protéines laitières modifiées enzymatiquement

Skimmilk Solids as Substrate for the Preparation of Casein Enzymatic Hydrolysates

“…1C and D). As reported by Turgeon et al (1991), DH values obtained with the OPA method were lower (~35%) than those obtained with the pH-stat technique. This may be associated with an overestimation of the l/(~ factor used in the DH calculation of the pHstat technique.…”

“…Effect of substrates on composition of hydrolysate fractions obtained with two-step ultrafiltration Four distinct hydrolysate fractions were obtained from the 2-step ultrafiltration (UF) process of Turgeon and Gauthier (1990): reaction mixture (RM), total hydrolysate (TH), mixture of polypeptides (MP) and amino acid and small peptides fraction (AA). Low-heat skimmilk powder (LH-SMP) was used as the substrate, and it was compared to sodium caseinate (SC).…”

“…The procedure described by Turgeon and Gauthier (1990) was applied, using the enzymatic conditions previously described but adjusted for the following larger-scale process: 100 kg of 3.5% w/w protein solution, pH 8.0, 4O"C, E:S ratio of 1:200, constant pH adjustment during hydrolysis by addition of 4N NaOH. After 45 min hydrolysis, proteolytic products were removed continuously by ultrafiltratibn (UF) using two membranes with nominal molecular weight cut-off of 30,000 Daltons (HF26-5-43-PM30, Romicon Inc., Wobcrn, MA).…”

“…These results were compared with sodium caseinate as reference, in order to select the most suitable substrate. Sodium caseinate and the selected substrate were then hydrolyzed with trypsin and chymotrypsin using a two-step ultrafiltration process described by Turgeon and Gauthier (1990). Finally, hydrolysate fractions from this process were characterized for overall composition, molecular weight distribution profile of peptidic components, and amino acid contents.…”

Whey Changes during Processing Determined by Near Infrared Spectroscopy

“…Thus, the dairy industry needs rapid methods to evaluate heat denaturation of whey proteins after cheese making and during further processing. Also the functionality of whey proteins can be improved by enzymatic hydrolysis (Lieske and Konrad, 1996;Turgeon et al, 1991). This must be controlled during processing, however, in order to stop the reaction at a specific degree of hydrolysis (DH) corresponding to optimal functionality few methods are adapted for follow-up of enzymatic hydrolysis of proteins at an industrial scale.…”