Lipid waxes

The octanol-water partition coefficient KqW provides a direct estimate of hydrophobicity or of partitioning tendency from water to organic media such as lipids, waxes and natural organic matter such as humin or humic acid. It is invaluable as a method of estimating KoC, the organic carbon-water partition coefficient, the usual correlation invoked being that of Karickhoff (1981)... 

This is a practical way of removing water from plant tissues when water is needed for homogenization or when the dry material cannot be ground to a powder due to the presence of lipids, waxes, or sugars. 

Anonymous. (2006b). Waxes Structure, composition, occurrence and analysis [Online] http /www.lipidlibrary.co.uk/Lipids/waxes/ (posted 20-02-2006 verified 27-02-2006). 

Waxes are the simplest hydrolyzable lipids. Waxes are esters (KCOOR ) formed from a h h molecular weight alcohol (R OH) and a fatty acid (RCOOH). 

A group termed other esters includes a large variety of functionally diverse lipids. Wax esters are a typical example. The term wax is used commonly for esters of long-chain fatty acids with long-chain primary alcohols, but sometimes it is used for the entire mixture of lipids that contain waxes. Ester waxes are present in both plants and animals where they form the water-repellent surface coating (e.g., skin surface of animals and the leaf cuticle). Esters of normal alcohols with monobranched or multibranched fatty acids have been found in the preen glands of birds (2). Complex waxes (in which either the fatty acid or the alcohol component or both has a complex structure) have been isolated from some bacteria. Diesters... 

Leather. Leather is animal skin that has been treated to produce pliancy and resistance to rotting. The tanning process by which leather is made is very old, but it is still not completely understood, mainly because the structure of animal skin is still unknown. In general, skin is polypeptide-containing collagen (see Section 10.4.5), but there are also present various amounts of keratin, reticulin, elastin, and water, plus other components such as carbohydrates, lipids, waxes, and triglycerides (1311). 

Waxes Another type of lipid, waxes, also contain fatty acids. A wax is a lipid that is formed by combining a fatty acid with a long-chain alcohol. The general structure of these soft, solid fats with low melting points is shown below, with x and y representing variable numbers of CH2 groups. 

Other lipids. Waxes are major lipids in a few organisms (e.g., jojoba, sperm whale). Cutins (condensation polymers of hydroxy fatty acids) are discussed in a later chapter (Kolattukudy et el.. Chap. 10). Hydrocarbons other than isopentenoid compounds occur in a variety of species. 

Compounds in this group are well characterized in organic chemistry. This group includes carbohydrates in the form of simple sugars, hemicellulose, and cellulose, proteins, lipids, waxes, and oils. 

Complex polymers Cellulose, hemicellulose, proteins, lipids, waxes, lignin... 

In addition to the amino-sorbents, other sorbent types have also been tested to exploit possibilities to remove co-extractives not or marginally removed by PSA, such as lipids, waxes, chlorophyll. Acidic, neutral, and basic alumina sorbents were found to remove, although to a slightly smaller extent, similar co-extractives as amino-sorbents, however, with less influence on pH. These sorbents, being much cheaper than PSA, will thus be more intensively studied in future. 

The THM reaction linked to GC, GC/mass spectrometry (MS), and MS has been successfully applied to the chemical characterization of a number of synthetic and natural products, including resins, lipids, waxes, wood products, soil sediments, and microorganisms. This technique is also very effective for the detailed characterization of the synthetic polymeric materials, especially the condensation polymers, such as polyesters and polycarbonates, because many simplified pyrograms are usually obtained that consist of peaks of methyl derivatives from the constituents of the polymer samples almost quantitatively. In this chapter, the instrumental and methodological aspects of Py-GC in the presence of the organic alkali are briefly described, and then some typical applications to the precise compositional analyses and microstructural elucidation inclusive of the intractable cross-linking structures for various condensation type polymeric materials are discussed. 

Generally, microalgae lipids include nentral lipids, polar lipids, wax esters, sterols, and hydrocarbons, as well as phenyl derivatives (Naik et al, 2010). For biodiesel prodnction, natural lipids, which are nonpolar, are always targeted. Typically, most of the lipids produced from microalgae strains that have been tested for biodiesel prodnction have fatty acid constitutions similar to most common vegetable oils (Becker, 2004 Huang et al., 2012), as shown in Table 6.1. 

Blends with hydrophobic materials (lipids, waxes) have been shown to improve moisture resistance of both polysaccharide and protein films. 

Fig. 1. Structure of triacylglycerols (I), i.e. the typical reserve lipids of oil seeds, and of ionic and non-ionic polar lipids (II), such as glycerophospholipids and glycerogalactolipids, which function as membrane lipids. Wax esters (III) are only formed in jojoba (Simmondsia chinensis) seeds as energy reserves. (Rj, R2, R3 various acyl moieties R4 alkoxy moiety X various polar head groups of ionic and non-ionic membrane lipids)...

When the content of essential oil is low in the raw material or the aroma constituents are destroyed hy steam distillation or the aroma is lost by its solubility in water, then the oil in the raw material is recovered by an extraction process. Examples are certain herbs or spices (cf. 22.1.1.1) and some fruit powders. Hexane, triacetin, acetone, ethanol, water and/or edible oil or fat are used as solvents. Good yields are also obtained by using liquid CO2. The volatile solvent is then fully removed by distillation. The oil extract (resin, absolue) often contains volatile aroma compounds in excess of 10% in addition to lipids, waxes, plant pigments and other substances extractable by the chosen solvent. Extraction may be followed by chromatographic or counter-current separation to isolate some desired aroma fractions. If the solvent used is not removed by distillation, the product is called an extract. The odor intensity of the extract, compared to the pure essential oil, is weaker for aromatization purposes hy a factor of 1Q2 to 10 ... 

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