Food characterization chromatographic techniques

Various chromatographic techniques have been employed for the purification and characterization of B-phycoeryhtrin (B-PE) from the unicellular red algae Porphyridium cruentum. B-PE is a biliprotein containing a chromophore. The research was motivated by the importance of B-PE in light-sensing elements in biosensors and by the possible application in food... 

Analytical chemistry applied to foods widely uses separation techniques in order to characterize foods on the basis of their major and minor constituent compounds. The minor compounds often highlight important differences rather than the major compounds. Chromatographic techniques have been widely applied however, when only gas chromatography (GC) was available, the application of this technique was severely limited by the thermal stability of the analytes. Derivatization reactions are able to somewhat protect organic molecules from degradation, but generally these procednres are rather time consuming and, sometimes, artifacts could be formed. 

HPLC analysis of food proteins and peptides can be performed for different purposes to characterize food, to detect frauds, to assess the severity of thermal treatments, etc. To detect and/or quantify protein and peptide components in foods, a number of different analytical techniques (chromatography, electrophoresis, mass spectrometry, immunology) have been used, either alone or in combination. The main advantages of HPLC analysis lie in its high resolution power and versatility. In a single chromatographic run, it is possible to obtain both the composition and the amount of the protein fraction and analysis can be automated. 

There are examples in the literature for the application of LC-MS-NMR in the pharmaceutical industry. In the area of natural products, this technique has been applied as a rapid screening method of searching unknown marine natural products in chromatographic fractions [108] and for the separation and characterization of natural products from plant origin [109, 110]. Another application is in the area of combinatorial chemistry [111]. In the field of drug metabolism, LC-MS-NMR has been extensively applied for the identification of metabolites [112-120]. And finally, LC-MS-NMR has been used for areas such pharmaceutical research [35,121,122], drug discovery [123], degradation products [101], and food analysis [124,125]. 

Volatile decomposition products from autoxidized linoleic acid and methyl linoleate were characterized for their intense aroma and flavor impact by capillary gas chromatography-olfactometry. This technique involves sniffing the gas chromatograph effluent after stepwise dilution of the volatile extract. The most intense volatiles included hexanal, c/ -2-octenal, /ra. s-2-nonenal, l-octene-3-one, 3-octene-2-one and trans-l-ociQmX (Table 4.2). This analytical approach does not, however, consider the effects of complex interactions of volatiles occurring in mixtures produced in oxidized food lipids. 

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