- Peptides

Over the last decade many efforts have been made to develop techniques and methods for the separation, purication, and characterization of food proteins and peptides (Careri and Mangia, 2003). The qualitative and quantitative analysis of peptides by different high-performance liquid chromatography (HPLC) modes has become a common practice in most laboratories due of its versatility, short analysis times, high resolution, and effective separations, and because its suitability to automation procedure (González

3.1 Introduction .................................................................................................................................... 69 3.2 Food Peptide Analysis .................................................................................................................... 70

3.2.1 Sample Preparation............................................................................................................ 70 3.2.1.1 Extraction and Preliminary Sample Clean-Up .................................................. 71 3.2.1.2 Fractionation by Ultraltration .......................................................................... 75 3.2.1.3 Fractionation by Low-Pressure Liquid Chromatography .................................. 75 3.2.1.4 Fractionation by Solid-Phase Extraction ........................................................... 76

3.2.2 Peptide Separation ............................................................................................................. 76 3.2.2.1 Reversed-Phase Chromatography ...................................................................... 76 3.2.2.2 Ion-Exchange Chromatography ......................................................................... 76 3.2.2.3 Size-Exclusion Chromatography ....................................................................... 77 3.2.2.4 Hydrophilic Interaction Chromatography ......................................................... 78 3.2.2.5 Hydrophobic Interaction Chromatography ........................................................ 78 3.2.2.6 Afnity Chromatography .................................................................................. 78 3.2.2.7 Multidimensional Separation ............................................................................. 79 3.2.2.8 Miniaturized Techniques ................................................................................... 79

3.2.3 Peptide Detection............................................................................................................... 80 3.2.3.1 Absorbance Detection ........................................................................................ 80 3.2.3.2 Fluorescence Detection ...................................................................................... 81 3.2.3.3 Mass Spectrometry Detection ............................................................................ 82 3.2.3.4 Other Detection Methods ................................................................................... 84

3.3 Applications: Food Peptidomics .................................................................................................... 85 3.3.1 Biologically Active Peptides .............................................................................................. 85 3.3.2 Sensory and Functional Properties of Peptides ................................................................. 86 3.3.3 Allergenicity of Food Peptides and Proteins ..................................................................... 87 3.3.4 Authenticity, Origin, and History of Food Products ......................................................... 87

3.4 Future Prospects ............................................................................................................................. 88 Acknowledgments .................................................................................................................................... 88 References ................................................................................................................................................ 88

de Llano and Polo, 2003). Practically all known mechanisms have been employed in the chromatographic separations of food peptides, for example, separation based on molecular size (size-exclusion chromatography, SEC), on charge (ion-exchange chromatography, IEX), on hydrophilic interaction (hydrophilic interaction liquid chromatography, HILIC), on afnity (afnity chromatography, AC), and even on combinations thereof of these (Issaq, 2001). However, reversed-phase (RP) chromatography is the most commonly used technique to separate mixtures of peptides from foodstuffs (Polo et al., 2000). In addition, mass spectrometry (MS) detection has become the preferred choice for peptide analysis in foodstuff and protein hydrolysates in laboratories dealing with proteome research and food analysis.