Characterization of bitter peptides in casein hydrolysates using comprehensive two-dimensional liquid chromatography

Advances in separation and identification of biologically important milk proteins and peptides

“…It was confirmed that the increasing bitterness of casein hydrolysate was related to higher concentration of peptides that possessed high hydrophobicities and molecular weights smaller than 6.5 kDa. This method demonstrated that based on sample elution pattern, the bitter taste of hydrolysate can be predicted [109].…”

“…For example, specific enzymatic techniques have been applied [105,106], and exopeptidases have been used that cleaved the protein at the site adjacent to hydrophobic amino acids or cut off hydrophobic amino acids from protein terminus [107,108]. Recently, the combination of two separation techniques has been used in 2D-LC arrangement [109], that is, SEC and RPLC for the characterization of bitter peptides in casein hydrolysates. Herein, 2D-LC method was applied to correlate both hydrophobicity and size of peptides to their bitterness and predict their sensory properties.…”

The Problem of Bitter Peptides Formed in the Process of Cheese Ripening

“…Z publikovaných výzkumů dále vyplývá, že v hořkých peptidech bývají nejvíce obsaženy hydrofobní l-aminokyseliny leucin, isoleucin, prolin, valin, fenylalanin, tyrosin a tryptofan, často je přítomna i kyselina glutamová, zatímco sirné aminokyseliny cystein a většinou methionin chybí 24,25,43 .…”

Two Multidimensional Chromatography/High-Resolution Mass Spectrometry Approaches Enabling the In-Depth Metabolite Characterization Simultaneously from Three Glycyrrhiza Species: Method Development, Comparison, and Integration

“…MDC can be operated in either the online or the offline mode, mainly including the applications of two-dimensional liquid chromatography (2D-LC) and three-dimensional liquid chromatography (3D-LC). , By MDC, the column combinations with large separation differences (referred to as high orthogonality) are often pursued. − Online 2D-LC has the merits of high automation, fast analysis speed, and good reproducibility, but it strongly depends on the availability of instruments . In contrast, the offline mode is highly accessible in the laboratories, flexible in integrating different mechanisms of separation, and free of the solvent effect, but often involves complex operations (e.g., eluate collection, solvent removal, and redissolution for sample injection). − In addition, 2D-LC can be divided into the comprehensive (LC × LC) and heart-cutting 2D-LC (HC-2D-LC) modes according to all of the one-dimensional fractions, or part of them are transferred and further separated by second-dimensional chromatography. , Comparatively, the comprehensive 2D-LC is advantageous in separating the complex components by feat of the greatly increased peak capacity and enhanced selectivity in separation, while HC-2D-LC selectively captures or enriches the target component(s), thus is more suitable for the quantitative assays. − Our recent research established two offline 3D-LC strategies by sequentially integrating ion exchange chromatography, hydrophilic interaction chromatography, and reversed-phase chromatography (IEC-HILIC-RPC) prior to the ultimate monitoring by high-resolution mass spectrometry (HRMS), which enabled the efficient discovery of numerous potential unknown structures. The use of a strong anion exchange (SAX) column in the first-dimensional ( 1 D) chromatography fractionated the total extracts of ginseng flowers into the acidic and the neutral fractions, while the application of a strong cation exchange (SCX) column in the 1 D chromatography separated the total extracts of Uncaria sessilifructus into the alkaloids and the nonbasic components .…”