Food components phospholipids

In a commercial response to the potential value of sphingolipids as functional food components, a patented process for preparing milk products enriched in both phospholipids and sphingolipids was developed (Dewet-tinck and Boone, 2002). These products are obtained by ultrafiltration of byproducts from the direct processing of milk or from the further processing of directly acquired byproducts. The ultrafiltration membrane used had a cut-off value ranging from 5,000 to 20,000 Da. 

Liposomes have been used by the pharmaceutical industry to deliver a range of drugs. Liposomes are made of phospholipid bilayers with one of more aqueous compartments depending on whether they are unilamellar, multilamellar, or multivesicular vehicles. Because of the bilayer structures they can adopt, they are versatile vehicles as carriers of water-soluble, oil-soluble as well as amphiphilic components. Hence, they can be used to encapsulate a wide range of food components including flavors, oils, amino acids, vitamins, minerals antimicrobials, and enzymes. Their potential applications in the food industry have been discussed by Mozafari et al. (2008)). Examples of the potential applications of liposomes in food include the delivery of cheese ripening enzymes and natural antioxidants (e.g., vitamin E). 

Lipids affect the functional properties of food for example, they help to retain carbon dioxide in dough, thus increasing the final volume of bakery products. Polar lipids are useful in improving the cohesiveness of food components they contribute to the pasting properties of cereal doughs, stabilize the dispersion, and also affect the surface properties. Phospholipids and monoacylglycerols are useful in this respect (see Chapter 4). 

No discussion of the use of biotransfarmation in lipid chemistry would be complete without some mention of chemical transformation relating to fatty adds. Fatty adds are a major component of the lipid fraction of organisms. They are mainly found as components of triglycerides and phospholipids, although they may occur in smaller quantities as free fatty adds or as esters of other moieties. Fatty adds, either as free adds or as esters, are valuable commodities in the food and cosmetics industries. They may also serve as precursors of a variety of other compounds. 

In addition to phenolic substances, there are other components present in foods which have no antioxidant activity of their own, but which increase that of phenolic antioxidants. They are called synergists, and they should be accounted for in any discussion of antioxidant activity. Polyvalent organic acids, amino acids, phospholipids (lecithin) and various chelating agents belong to this group. Proteins may modify the efficiency of antioxidants as they react with the reaction products of both antioxidants and synergists. 

Bile is an important product released by the hepatocytes. It promotes the digestion of fats from food by emulsifying them in the small intestine (see p. 2770). The emulsifying components of bile, apart from phospholipids, mainly consist of bile acids and bile salts (see below). The bile also contains free cholesterol, which is excreted in this way (see p. 312). 

Harris and Lindsay (3) reported that panelists were able to detect off-flavors in reheated fried chicken after 2 hr of refrigeration. The high concentration of polyunsaturated fatty adds in muscle phospholipids supplies readily oxidizable lipids, and these components play an important role in the development of WOF (4, 5). The rising demand for precooked convenience foods has increased the importance of controlling WOF. 

The value of antioxidant protection by way of natural food sources has been pointed out in the literature with considerable frequency. Among the components of soy flour known to have some antioxidant properties are isoflavones and phospholipids. Amino acids and peptides in soybean flour also possess some antioxidant activity. There also may be some antioxidant impact from aromatic amines and sulfhydryl compounds. 

Although phospholipids are natural components of nearly all food products, the analysis of the phospholipid composition is of importance mainly in the certification and quality control of lecithins. According to the European Analytical Subgroup of the International Lecithin and Phospholipid Society (ILPS), there is an urgent need for a standard method for the determination of the PL composition, for this would allow a better characterization of lecithin and PL products (15,16). Besides, the nonavailability of good calibration standards is a major problem when comparing analytical results between companies. In order to try to solve the latter problem, the ILPS proposes a calibration standard whose composition is certified by 31P-NMR as an absolute tech-... 

The structure of the interfacial layers in food colloids can be quite complex as these are usually comprised of mixtures of a variety of surfactants and all are probably at least partly adsorbed at interfaces which even individually, can form complex adsorption layers. The layers can be viscoelastic. Phospholipids form multi-lamellar structures at the interface and proteins, such as casein, can adsorb in a variety of conformations [78]. Lecithins not only adsorb also at interfaces, but can affect the conformations of adsorbed casein. The situation in food emulsions can be complicated further by the additional presence of solid particles. For example, the fat droplets in homogenized milk are surrounded by a membrane that contains phospholipid, protein and semi-solid casein micelles [78,816], Similarly, the oil droplets in mayonnaise are partly coated with granular particles formed from the phospho and lipo-protein components of egg yolk [78]. Finally, the phospholipids can also interact with proteins and lecithins to form independent vesicles [78], thus creating an additional dispersed phase. 

Canola Oil occurs as a light yellow oil. It is typically obtained by a combination of mechanical expression followed by n-hexane extraction, from the seed of the plant Brassica juncea, Brassica napus, or Brassica rapa (Fam. Cruciferae). The plant varieties are those producing oil-bearing seeds with a low erucic acid (C22 i) content. It is a mixture of triglycerides composed of both saturated and unsaturated fatty acids. It is refined, bleached, and deodorized to substantially remove free fatty acids phospholipids color odor and flavor components and miscellaneous, other non-oil materials. It can be hydrogenated to reduce the level of unsaturated fatty acids for functional purposes in foods. It is a liquid at 0° and above. 

Phospholipids (Figure 3) are constituents of membranes and are only minor components of oils and fats, sometimes responsible for cloudiness. They are usually removed during degumming, the residue from soybean oil processing being a source of phospholipids used as food emulsifiers. The term lecithin is used very loosely for such material, and it may variously mean phosphatidylcholine, mixed glycerophospholipids, or cmde phospholipid extracts from various sources. Where possible, more specific nomenclature or the source and purity should be used (14). 

Solvent-extracted rapeseed oil has been found to contain the highest level of phosphorus. For this reason, it is common practice to degum solvent-extracted oil or the mixed crude oil from pressing and subsequent solvent-extraction. As the double-zero rapeseed varieties such as canola became available, the applications of rapeseed lecithin have developed positively. Where at first rapeseed lecithin was applied as an emulsifier and energy component in animal feed, the recent concerns about GMO soybean varieties in some parts of the world have increased the market value of the softseed lecithins for food applications (45). The phospholipid composition is similar to soybean lecithin with variations due to crop and processing conditions. The rapeseed phospholipid compositions in Table 12 have been confirmed by recent data, whereas the soybean lecithin composition in... 

Lipids constitute below 1% of the weight of fruits, vegetables, and lean fish 3.5% of milk 6% of beef 32% of egg yolk and 85% of butter. The lipids contained in the food raw materials in low quantities serve mainly as components of protein-phospholipid membranes and perform metabolic functions. In fatty commodities the majority of the lipids are stored as depot fat in the form of triacylglycerols. The lipids of numerous food fishes, such as orange roughy, mullets, codfish, and sharks,... 

---