Blue cheese peptides

Gonzalez de Llano et al. (47) separated amino acids from low-molecular-weight peptides by means of size-exclusion chromatography on Sephadex G-10, with water as the solvent, as a preparatory step before RP-HPLC analysis of peptides from blue cheeses soluble in 5% PTA (Fig. 1). This technique has also been used (51a) to eliminate the amino acids from the ethanol-... 

The reaction of amines and amino acids with orthophthaldehyde has been widely used in postcolumn and precolumn derivatization in analyses of foods (99-104) and in analyses of peptides from biological samples. Figure 2 (87) presents a chromatogram for OPA derivatives of tryptic peptides from two proteins. The sensitivity of the method was on the order of picomoles. The authors have themselves performed postcolumn OPA derivatization of low-molecular-weight peptides from blue cheeses separated by reversed-phase chromatography (86). 

Gonzalez de Llano, D., Ramos, M., and Polo, C. (1987). Gel filtration and high performance liquid chromatographic analysis of phosphotungstic acid soluble peptides from blue cheeses. Chromatographia 23, 764-766. 

Undoubtedly, the products of these primary biochemical events, i.e., fatty and other acids, peptides, and amino adds, contribute to cheese flavor, perhaps very significantly in many varieties and proteolysis certainly has a major influence on the various rheological properties of cheese, e.g., texture, meltability, and stretchability. However, the finer points of cheese flavor are almost certainly due to further modification of the products of the primary reactions. The most clear-cut example of this is the oxidation of fatty acids to methyl ketones in blue cheeses. Catabolism of amino acids leads to the production of numerous sapid compounds, including amines, carbonyls, acids, thiols, and alcohols. Many of these compounds may interact chemically with each other and the compounds of other reactions via the Maillard and Strecker reactions. At present, relatively little is known concerning the enzymology of amino acid catabolism in most cheeses and even less is known about the chemical reactions. It is very likely that research attention will focus on these secondary and tertiary reactions in the short-term future. 

Proteolysis during maturation is essential in most cheese varieties. The extent of proteolysis varies from very limited (e.g.. Mozzarella) to very extensive (e.g.. Blue mould varieties) and the products range in size from large polypeptides, comparable in size to intact caseins, through a range of medium and small peptides to free amino acids. Clearly, no one proteolytic agent is responsible for such a wide range of products. 

When the presence of 3-casomorphins was examined in commercial cheese products, no peptides were found or their concentration in the cheese extract was below 2 4g/ml (Muehlenkamp Warthesen, 1996). 3-casomorphins 5, -6, -7 and their precursors were identified in various types of cheeses, e.g. Swiss, Elsberg, Cheddar, Gouda, Feta, Blue, Brie, Parmesan and Crescenza (Addeo et al., 1992 Jarmolowska, Kostyra, Krawczuk, Kostyra, 1999 Sabikhi Mathur, 2001 Smacchi Gobbetti, 1998). 

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