Phospholipids biological tissue

In general it has to be stated that molecular species analysis of phospholipids is not frequently applied in food analysis most of the studies involving molecular species are instead found in the fields of biochemistry and nutrition. Thus, in the recent reviews by Bell and by Olsson and Salem, special emphasis has been given to the characterization of biological tissue samples (83,84). However, the molecular species composition has been shown to affect the accuracy of the quantification of phospholipid classes and hence is important in food analysis too (47,52). In the vast majority of published methods, isocratic elution has been used. In our opinion, this should be ascribed mainly to the fact that the traditional UV detector remains. Keeping account of the inherent problems associated with UV detection of underivatized phospholipids, it is astonishing that ELSD has hardly been exploited in this subdomain. As far as the stationary phase is concerned, nearly all methods prefer octadecyl-coated stationary phases. 

It has been observed that the content of secondary oxidation products, such as malonaldehyde (MA), decreases with increased lipid oxidation, which can be explained by further reaction of MA with proteins. MA reacts with compounds containing primary amino groups (proteins, amino acids, DNA, phospholipids) to form fluorescent products (Figure 5) (37). A fluorescence assay has been successfully used to assess lipid oxidation in muscle foods and biological tissues. 

Indeed, Coulombic interactions are important or even dominant in almost all biological. systems, such as proteins, DNA, or charged membranes. Dipolar interactions, on the other hand, play a proinineut role in phospholipid bilayers [222, 223], and they are always important because of the omnipresence of dipolar water molecules in biological tissues and electrolyte solutions. 

We can envisage that the distribution of fatty acid residues observed with the phospholipids in biological tissues provides the correct fluidity at a particular environmental temperature to match the required diffusion or rate of metabolic processes required for the tissue. Thus in membranes where metabolic and diffusion processes must be rapid, such as in the mito-... 

Eibisch, M., Fuchs, B., Schiller, J., Su6, R., and Teuber, K. 2011. Analysis of phospholipid mixtures from biological tissues by matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) A laboratory experiment. J. Chem. Educat., 88 503-507. 

Off-line coupling of HILIC and the reversed phase was realized by lisa and coworkers for lipidomic profiling of biological tissues [76] using both UV and MS detection (namely, ESI for polar phospholipid species and APCI interface for nonpolar TAG species). 

Because all food derives from biological tissues and because all tissues contain biological membranes, all foods contain, to a greater or lesser extent, structural fats. These are predominantly phospholipids and glycolipids (Chapter 6) with, in animal tissues, cholesterol and in plant tissues, the plant sterols. Thus, the lean part of meat contains the structural lipids, phospholipids and cholesterol of the muscle membranes and minor quantities of gly colipids. Consumption of tissues like brain would introduce larger quantities of animal sphingolipids into the diet. Dairy products contribute small amounts of structural lipids because of the presence of the fat globule membrane. The structural lipids of plants that are important in... 

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