Emulsification of chemical and enzymatic hydrolysates of beta-lactoglobulin: characterization of the peptides adsorbed at the interface

Bovine beta-Lactoglobulin (BLG) was cleaved by BNPS-skatole (2-(2'-nitrophe nylsulfenyl)-3-methyl-3'-bromoindolenine), trypsin, or pepsin in 40% ethano l before emulsification with hexadecane in order to characterize the peptid es active at the interfaces. The total digests and the different phases obt ained after emulsification were analyzed by RP-HPLC to separate the peptide s according to their gradual order on a hydrophilicity-to-hydrophobicity sc ale. In each case, hydrophobic peptides were recovered in the creamed phase and characterized by mass spectrometry and sequencing. After tryptic hydro lysis, short peptides were identified at the interfacial layer as fragments S-21-L-32, V-41-L-57, V-41-K-60, and W-61-K-70 linked to L-149-I-162 by a C-66-C-160 bond. It indicates that the hydrophilic/hydrophobic distribution of the amino acids in the sequence of the fragments is more relevant to ad sorption than the length of the peptide. BNPS-skatole and peptic hydrolysis produced larger hydrophobic peptides which were also recovered in the crea med phase of the emulsion and characterized.