Emulsification of chemical and enzymatic hydrolysates of β‐lactoglobulin: characterization of the peptides adsorbed at the interface

Bovine β‐Lactoglobulin (BLG) was cleaved by BNPS‐skatole (2‐(2′‐nitrophenylsulfenyl)‐3‐methyl‐3′‐bromoindolenine( trypsin, or pepsin in 40% ethanol before emulsification with hexadecane in order to characterize the peptides active at the interfaces. The total digests and the different phases obtained after emulsification were analyzed by RP‐HPLC to separate the peptides according to their gradual order on a hydrophilicity‐to‐hydrophobicity scale. In each case, hydrophobic peptides were recovered in the creamed phase and characterized by mass spectrometry and sequencing. After tryptic hydrolysis, short peptides were identified at the interfacial layer as fragments S₂₁–L₃₂, V₄₁–L₅₇, V₄₁–K₆₀, and W₆₁–K₇₀linked to L₁₄₉–I₁₆₂ by a C₆₆–C₁₆₀bond. It indicates that the hydrophilic/hydrophobic distribution of the amino acids in the sequence of the fragments is more relevant to adsorption than the length of the peptide. BNPS‐skatole and peptic hydrolysis produced larger hydrophobic peptides which were also recovered in the creamed phase of the emulsion and characterized.