Phospholipids lecithins

In media selective for enterobacteria a surface-active agent is the main selector, whereas in staphylococcal medium sodium and lithium chlorides are the selectors staphylococci are tolerant of salt concentrations to around 7.5%. Mannitol salt, Baird-Parker (BP) and Vogel-Johnson (VJ) media are three examples of selective staphyloccocal media. Beside salt concentration the other principles are the use of a selective carbon source, mannitol or sodium pyruvate together with a buffer plus acid-base indicator for visualizing metabolic activity and, by inference, growth. BP medium also contains egg yolk the lecithin (phospholipid) in this is hydrolysed by staphylococcal (esterase) activity so that organisms are surrounded by a cleared zone in the otherwise opaque medium. The United States Pharmacopeia (1990) includes a test for staphylococci in pharmaceutical products, whereas the British Pharmacopoeia (1993) does not. 

Fig. 6.3 Separation of lecithin phospholipids by HPLC with evaporative light scattering...

Fat includes triglycerides, sterols, lecithins (phospholipids), essential oils, fat-soluble pigments such as chlorophyll, and similar substances. The AOAC recommends that anhydrous diethyl ether kept over freshly cut sodium pieces is used for the extractant (Padmore, 1990, p. 79), but we prefer to use petroleum spirit, also called light petroleum and petroleum ether, with a boiling range of 40-60°C, as it is a less hazardous solvent. 

PE), usually present in the ratio of approximately 3 1 and making up about 90% of the total weight of the lecithin phospholipids (Table 9.1). It is known that the two main phospholipids account for most of the stabilization and emulsification activity of the lecithin, but it is thought that minor components such as sphingomyelin and phosphatidic acid also play some as yet undefined role in the process. It might be emphasized here that the natural mixture of components is more effective at stabilizing emulsions than any of the major components in either purified or synthetic form, alone or in artificial admixtures. 

The key to long-term physical stability of aqueous nanosuspensions is the selection of a suitable water-soluble surfactant or polymer as an external particle stabilizer to prevent particle growth. Several potential stabilizers are lecithin, phospholipids, poloxamers, and polysorbates. 

Dor-Lee . [Van Den Bergh Foods] Lecithin (phospholipids) emulsifier for foods, Cheung gunt... 

L-a-Phosphatidyl choline (lecithin) phospholipid commonly found in plants, but much less so in microorganisms... 

Some examples of successful commercial selective extractions are the removal of caffeine from coffee or the solubilization of nicotine from tobacco both accomplished on moist matrices to aid in selectively solubilizing the alkaloid component. Selective extraction has been demonstrated for the segregation of essential oil from other lipid components in natural extracts derived from fruits and for the separation of aroma components in cocoa butter from the base oil. Other enrichment SEE schemes that have been reported include the fractionation of carotenoid from leaf protein concentrate [25], the fortification of sterols in seed oils [26], and the isolation of lecithin (phospholipid-containing fraction) from triglycerides [27]. 

Amphoteric surfactants possess both an anionic and a cationic function. In small-scale preparation they are little used but their role may increase in the future. Examples are long chain betains and phospholipids (e.g. lecithin). Phospholipids play an important role as emulsifiers and micelle formers for parenteral emulsions (see Sect. 13.5.7) and micellar solutions and also in liposome technology. 

American Lecithin Company s high grade, unmodified, de-oiled Lecithins come in three types of granulation. These granules/ powders are slightly yellow-tan in color. They contain a high level of natural, functional Lecithin Phospholipids. These products conform to the Food Chemicals Codex. 

Fure membranes of dipalmitoyl lecithin phospholipids are models of biological membranes. They melt at 7 m = 41 C. Reversible melting experiments indicate that AH, = 9kcal mol. Calculate... 

Symmetrical (two equal fatty acid chains) (Figure 5.4, 1) and asymmetrical (two different fatty acid chains) (Figure 5.4, 2) nonionic double-chain surfactants of the type A ,A -diacyl lysine polyoxyethylene glycol amide compounds, with a structural resemblance to natural lecithin phospholipids, have been reported by the authors lab [35-38] to determine the effect of several structural parameters (hydrophobic chain length, polyoxyethylene (POE) chain length and number of polyoxyethylene chains) on the physicochemical properties and biological performance of these natural mimics. 

Diehl, B. K. W. and Ockels, W. (1995) Quantitative analysis of lecithin phospholipid analysis with 31-P NMR spectroscopy, in Phospholipids Characterization, Metabolism and Novel Biological Application (eds G. Cevc and F. Paltauf), AOCS Press, Champaign, Illinois, pp. 29-32. 

American Oil Chemists Society, Determination of lecithin phospholipids by HPLC, Official Method Ja 7b-91.211 West Bradley Ave., Champaign, IL 61826. 

Cationic surfactants may be used [94] and the effect of salinity and valence of electrolyte on charged systems has been investigated [95-98]. The phospholipid lecithin can also produce microemulsions when combined with an alcohol cosolvent [99]. Microemulsions formed with a double-tailed surfactant such as Aerosol OT (AOT) do not require a cosurfactant for stability (see, for instance. Refs. 100, 101). Morphological hysteresis has been observed in the inversion process and the formation of stable mixtures of microemulsion indicated [102]. 

A typical biomembrane consists largely of amphiphilic lipids with small hydrophilic head groups and long hydrophobic fatty acid tails. These amphiphiles are insoluble in water (<10 ° mol L ) and capable of self-organization into uitrathin bilaycr lipid membranes (BLMs). Until 1977 only natural lipids, in particular phospholipids like lecithins, were believed to form spherical and related vesicular membrane structures. Intricate interactions of the head groups were supposed to be necessary for the self-organization of several ten thousands of... 

Other Reactions of Phospholipids. The unsaturated fatty acid groups in soybean lecithin can be halogenated. Acetic anhydride combined with the amino group of phosphatidylethanolamine forms acetylated compounds. PhosphoHpids form addition compounds with salts of heavy metals. Phosphatidylethanolamine and phosphatidjhnositol have affinities for calcium and magnesium ions that are related to interaction with their polar groups. 

Names of companies (suppHers) are given in parentheses. ADM = Archer Daniels Midland ALC = American Lecithin Co. CS = Central Soya NP = Nattermann Phospholipid GmbH RI = Riceland. 

One important phospholipid is phosphatidylcholine, also called lecithin. Phosphatidylcholine is a mixture of diesters of phosphoric acid. One estei function is derived from a diacylglycerol, whereas the other is a choline [—OCH2CH2N(CH3)3] unit. 

Particular phospholipids display characteristic transition temperatures (Tm). As shown in Table 9.1, increases with chain length, decreases with unsaturation, and depends on the nature of the polar head group. For pure phospholipid bilayers, the transition occurs over a narrow temperature range. The phase transition for dimyristoyl lecithin has a peak width of about 0.2°C. 

Lecithin is a phospholipid, a class of compounds that make up cell membranes throughout the body. It is produced in the liver if the diet contains enough of the raw ingredients. 

Hauser, H. (1987). Spontaneous vesiculation of uncharged phospholipid dispersions consisting of lecithin and lysolecithin, Chem. 

Lecithin, a common phospholipid, has a hydrophobic tail and a hydrophilic head. 

The lipid bilayer of a cell membrane contains two layers of a phospholipid such as lecithin, arranged tail-to-tail. 

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. 

Phosphatidylcholine, commonly known as lecithin, is the most commonly occurring in natnre and consists of two fatty add moieties in each molecule. Phosphati-dylethanolamine, also known as cephahn, consists of an amine gronp that can be methylated to form other compounds. This is also one of the abundant phospholipids of animal, plant, and microbial origin. Phosphatidylserine, which has weakly acidic properties and is found in the brain tissues of mammals, is found in small amounts in microorganisms. Recent health claims indicate that phosphatidylserine can be used as a brain food for early Alzheimer s disease patients and for patients with cognitive dysfunctions. Lysophospholipids consist of only one fatty acid moiety attached either to sn-1 or sn-2 position in each molecule, and some of them are quite soluble in water. Lysophosphatidylchohne, lysophosphatidylserine, and lysophos-phatidylethanolamine are found in animal tissues in trace amounts, and they are mainly hydrolytic products of phospholipids. 

---