Improving the colloidal and sensory properties of a caseinate hydrolysate using particular exopeptidases

Food Funct. 2018 Nov 14;9(11):5989-5998. doi: 10.1039/c8fo01749b.

Abstract

Enzymatic hydrolysis with endopeptidases can be used to modify the colloidal properties of food proteins. In this study, sodium caseinate was hydrolyzed with Sternzym BP 25201, containing a thermolysin-like endopeptidase from Geobacillus stearothermophilus as the only peptidase, to a DH of 2.3 ± 1%. The hydrolysate (pre-hydrolysate) obtained was increased in its foam (+35%) and emulsion stability (+200%) compared to untreated sodium caseinate but showed a bitter taste. This hydrolysate was further treated with the exopeptidases PepN, PepX or PepA, acting on the N-terminus of peptides. Depending on the specificity of the exopeptidase used, changes regarding the hydrolysate properties (hydrophobicity, size), colloidal behavior (emulsions, foams) and taste were observed. No changes regarding the bitterness but further improvements regarding the colloidal stability (foam: +69%, emulsion: +29%) were determined after the application of PepA, which is specific for the hydrophilic amino acids Asp, Glu and Ser. By contrast, treatment with the general aminopeptidase PepN resulted in a non-bitter product, with no significant changes regarding the colloidal properties compared to the pre-hydrolysate (p < 0.05). Similar results to those for PepN (reduced bitterness compared to the pre-hydrolysate, enhanced colloidal stability compared to sodium caseinate) were also obtained using commercial Flavourzyme, which was reduced in its endopeptidase activity (exo-flavourzyme). In conclusion, the modifications obtained with the applied exopeptidases offer a potent tool for researchers and the industry to produce non-bitter protein hydrolysates with increased colloidal properties.

MeSH terms

  • Adult
  • Aminopeptidases / metabolism
  • Bacterial Proteins / metabolism
  • Caseins / chemistry*
  • Endopeptidases / metabolism
  • Exopeptidases / metabolism*
  • Female
  • Humans
  • Hydrophobic and Hydrophilic Interactions
  • Male
  • Middle Aged
  • Molecular Weight
  • Peptide Hydrolases / metabolism
  • Peptides
  • Protein Hydrolysates / chemistry*
  • Taste*
  • Young Adult

Substances

  • Bacterial Proteins
  • Caseins
  • Peptides
  • Protein Hydrolysates
  • pepN protein, Bacteria
  • Endopeptidases
  • Exopeptidases
  • Peptide Hydrolases
  • flavourzyme
  • Aminopeptidases