Natural fats, structure

In tile application of surfactants, physical and use properties, precisely specified, are of primary concern. Chemical homogeneity is of little significance in practice. In fact, surfactants are generally polydisperse mixtures, such as the natural fats as precursors of fatty acid-derived surfactant structures e.g., coconut oil contains glycerol esters of Cc-Qa fatly acids. Nonionic surfactants of die alcohol edioxylate type are polydisperse not only with respect to the hydrophobe but also in the number of edivlene oxide units attached. 

It should be remarked, that in several respects fatty oils and related products usually have a far less complicated character than have mineral oil products. The number of fatty acids occurring in natural fats is limited and certain structural elements, which contribute considerably to the composition of mineral oi s (cyclic compounds, branchings) hardly occur. On the other hand, phenomena such as cis-trans isomerism, al-... 

Litchfield, C. (1973)Taxonomic patterns in the triglyceride structure of natural fats. FetteSeif. Anstrichm., 75,223-231. 

As noted earlier, there are approximately 400 minor fatty acids in bovine milk fat about 40 are present at levels >0.01% (Table 1.5), while the remainder exist in trace amounts. Most of these fatty acids are of little practical importance and, hence, their nature and structure is of academic interest only. 

Keenan, T.W., Dylewski, D.P. 1995. Intracellular origin of milk fat globules and the nature and structure of the milk lipid globule membrane. In Advanced Dairy Chemistry-2-Lipids, 2nd edn (P.F. Fox, ed.), pp. 89-130, Chapman and Hall, London. 

The bilayer arrangement of fatty acid chains is the most common packing structure for natural fats, including milk fat. However, with quench cooling to 8°C, Lopez et al. (2001) found evidence of the coexistence of both the bilayer and trilayer lamellar structures in milk fat. 

Triglycerides. Structural analysis of the natural fat triglycerides is particularly difiicult because of the many possible molecular species which have very similar chemical and physical properties. Major advances in separation and analytical techniques since 1955 have revolutionized this field. The chemically different triglycerides are now separable by gas-liquid chromatography, by thin-layer chromatography, and/or by permeation chromatography. By use of selective enzymatic deacylation and phosphorylation techniques, the positional isomers can be separated and characterized (121). 

Crystallization from the emulsified state may lead to different nucleation processes than observed for the same fat in bulk liquid form. It has been suggested that nucleation often occurs at the interface of the droplet where surface-active agents are located. The general similarity of the lipophilic components of surfactants oriented at the surface may provide some ordering and structure for the lipid molecules within the droplet and enhance nucleation, as found for example by Kaneko et al. (40) for a hydrocarbon emulsion. Walstra (11) also suggests that formation of compound crystals from emulsions of natural fats may be different than the same fat crystallized from bulk liquid. The initial polymorph formed may also be different, with more stable polymorphs more likely to form in the emulsion (38). 

The relevance of the molecular structural diversity of the TAG to practical application may be understood by taking some examples of natural fats cocoa butter with major TAG of POP (l,3-dipalmitoyl-2-oleoyl-jn-glycerol), POS (1,3-palmitoyl-stearoyl,2-oleoyl-rac-glycerol) and SOS (l,3-distearoyl-2-oleoyl-jn-glycerol), milk fats whose major TAG are saturated-unsaturated mixed-acid TAG, and mixed-acid TAG with saturated fatty acids having different chainlengths (2). In these natural fats, few mono-acid TAG are present as major TAG components, and the major fats are composed of the mixed-acid TAG. Therefore, it is required to elucidate for the polymorphic structures of the mixed-acid TAG. 

Special Topic 3.1 describes how the shape of ethanol molecules allows them to attach to specific sites on nerve cell membranes and slow the transfer of information from one neuron to another. Special Topic 5.2 describes how the shapes of the molecules in our food determine whether they taste sweet or bitter. You will find out in Special Topic 17.2 that the fat substitute Olestra is indigestible because it does not fit into the enzyme that digests natural fat. The purpose of this section is to show you how to use Lewis structures to predict three-dimensional shapes of simple molecules and polyatomic ions. Let s start with a review of some of the information from Section 3.1, where this topic was first introduced. 

In foods something similar occurs during the crystallization of fats. Natural fats have a wide compositional range, implying that several different kinds of crystals have to be formed. This needs undercooling, but as soon as the first crystals have formed, other crystals nucleate on the existing ones. This must be due to epitaxy, since the various crystals are very similar in lattice structure. It is indeed observed that the undercooling needed is only by about 2 K. 

Vegetable oils and natural fats are traditional raw materials for the production of soaps and other surfactants. Coconut oil, palm and palm kernel oil, rape oil, cotton oil, tall oil, as well as the fats of animal origin (tallow oil, wool wax), present renewable raw sources. Linear paraffins and olefins (with terminal or internal double bond), higher synthetic alcohols, and benzene are fossil sources for surfactant production which are obtained from oil, natural gas and coal. Other auxiliary materials are required to construct amphiphilic surfactant structure, such as ethylene oxide, sulphur trioxide, phosphorous pentaoxide, chloroacetic acid, maleic anhydride, ethanolamine, and others. 

Whereas the biodiesel synthesis from natural fats or vegetable oils does not alter the ester structure of glycerolipids, the intentionally conducted overhydrogenation has recently created considerable interest as a new synthesis... 

Essential oils are usually derived from the non-seed parts of the plants with chemical composition other than the triglyceride structure of natural fats and oils. They refer to the subtle, aromatic liquids extracted from the flowers, seeds, leaves, stems, bark and roots of herbs, bushes, shrubs and trees through distillation. Essential oils are concentrated liquids containing volatile aromatic compounds. They are used in perfumery, aromatherapy, cosmetics, incense, medicine, household cleaning products and for flavouring food and drink. Their use in aromatherapy and other health care areas is growing. 

One-step chemical or biochemical modification of naturally produced structures under (1). Above examples are cellulose and starch derivatives, glucose and fructose, glycerol, fatly adds, ethanol, dtric add, glutamic and lactic add by fermentation, lactulose, lactitol, and lactobionic add by isomerization, hydrogenation, and oxidation, respectively, from ladose. Mother Nature offers definitely a variety of fine starting materials for spedahty chemicals. 

Olestra is a zero-calorie commercial fat substitute with the look and feel of natural fats. It Is a synthetic compound whose structure involves a novel combination of natural components. The core of olestra Is derived from sucrose, ordinary table sugar. Six to eight of the hydroxyl groups on the sucrose framework have long-chain carboxylic acids (fatty acids) appended to them by ester linkages. These fatty acids are from Cs to C22 in length. In the industrial synthesis of olestra, these fatty acids derive from... 

Solid substances with the same chemical composition and different crystal structure are called polymorphic forms or modifications. Each polymorphic form has characteristic properties (such as specific volume and melting point). The formation of a given polymorphic form depends on many factors (such as temperature, cooling rate of the liquid phase and type of solvent). In the solid crystal state, one polymorphic form is transformed into the other polymorphic forms without previous melting of the crystals. If one of the forms and another form is stable, these two polymorphic forms are called monotropic. The transformation occurs only in one direction, the stable form arises from the metastabile form. All natural fats are monotropic. 

The natural oleochemicals are obtained from natural oils with the least change in the structure of the carbon chain fraction. In contrast, synthetic oleochemicals are built up from ethylene to the desired carbon chain fraction or from oxidation of petroleum waxes. Fats and oils are renewable products of nature. One can aptly call them oil from the sun where the sun s energy is biochemically converted to valuable oleochemicals via oleo-chemistry. Natural oleochemicals derived from natural fats and oils by splitting or trans-esterification, such as fatty acids, methyl esters, and glycerine are termed basic oleochemicals. Fatty alcohols and fatty amines may also be counted as basic oleochemicals, because of their importance in the manufacture of derivatives (6). Further processing of the basic oleochemicals by different routes, such as esterification, ethoxylation, sulfation, and amidation (Fig. 12.1), produces other oleochemical products, which are termed oleochemical derivatives. 

An oil derived fatty acid is chemically combined into a polymer structure. All natural fats are triglycerides [ 1 mole of glycerine -f 2 molecules of fatty acid (saturated)]. Oils are formed from unsaturated fatty acids. All saturated fatty acids contain double bonds. 

Lipases are enzymes that specifically degrade fat. Lipases hydrolyze not just the fat on the outside of the hides and skins, but also the fat inside the skin structure. Once most of the natural fat has been removed, subsequent chemical treatments such as tanning, re-tanning and dyeing have a better effect. Lipases represent a more environmentally sound method of removing fat. For bovine hides, lipases allow tensides to be replaced completely. For sheepskins, which contain up to 40% fat, the use of solvents is... 

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