Innovative milk and whey protein hydrolysates

Generation of bioactive compounds from milk proteins is a possible way to obtain bioactive peptide ingredients having a health promoting activity in cardiovascular disease, inflammation and cancer. These peptide sequences are inactive in the native protein but can be released during digestion or produced during in vitro enzymatic hydrolysis. Industrial-scale production of bioactive compounds from food protein hydrolysis has contributed to the appearance on the market of commercial products with milk bioactive peptides. The aim of this study was to investigate an efficient way to produce milk protein hydrolysates from different substrates: milk protein concentrate, whey protein concentrate and sodium caseinate. These substrates were hydrolysed with two enzyme preparations at 50°C for 1 and 4 h at constant pH 7. Molecular mass distribution (by GPC), particle size (by laser light scattering analysis), degree of hydrolysis, turbidity and viscosity profiles of the hydrolysates, were evaluated. Both the used enzymes reached a hydrolysis degree up to 7% in all three substrates already after 1h with some differences in the 4h treatment. One enzyme showed best performance after 4h-treatment reaching 18% of hydrolysis with sodium caseinate. Particle size analysis suggested that the hydrolysed sodium caseinate can produce aggregates: this agrees with the turbidity test showing an absorbance increase at 550nm after hydrolysis, while in the other substrate it decreased. Viscosity decreased in all samples: according with GPC, after 1h incubation, more than 25% of the particles have a molecular mass below 1 kDa. Results showed a correlation between hydrolysis degree and molecular mass distribution, which is important for a possible influence of the hydrolysates addition as food ingredients. Additional studies were carried out to evaluate the effect of freeze and spray-drying on the viscosity and antioxidant properties of the hydrolysate and their incorporation into biscuits.