Animal and marine lipids

It is probable that our ancestors of several million years ago developed the characteristics leading to our modem biochemistry by eating animal fats (Crawford and Marsh, 1989 Sinclair and O Dea, 1990 O Dea, 1991). At first glance this should simplify discussion of animal fats, as shown by the basic fatty acids of Table 10.1. A popular shorthand notation is used to indicate the stmctures of common fatty acids. In the format x yn-z, x is the chain length or number of carbons in the chain, y is the number of methylene-interrupted cis ethylenic bonds and z is the inclusive number of carbon atoms from the terminal methyl group to the center of the nearest bond. As few as six fatty acids appear to adequately describe animal depot fats. Those fats listed are dominated by two fatty acids, 16 0 (palmitic) and 18 1 (oleic) add. Although tropical seed oils may be rich in C12-C18 saturated fatty adds (Elson, 1992), temperate oilseeds are rich in oleic acid and tend to include quantities of two fatty acids more unsaturated than oleic, especially 18 2n-6 (linoleic), and sometimes 18 3n-3 (linolenic). Even the original rapeseed (Brassica sp.) oil, with up to 50% of 22 ln-9 (emdc) acid usually had approximately 20% 18 2/1-6 and 10% 18 3/i-3 adds (Ackman 1983, 1990). 

To achieve the same level of 18 3/i-3 in beef, it would have to be provided by an encapsulated or protected fat as shown in Table 10.1 

Kamel et al. (eds.), Technological Advances in Improved and Alternative Sources of Lipids Chapman Hall 1994 

Diet type Beef (suet) Pork (lard) Lamb Mutton Horse Chicken  

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Figure 2-5 Chromatogram of Milk Fat Fatty Acid Composition Analyzed as Butyl Esters on a 30-m Capillary Column. Source Reprinted from R.G. Ackman, Animal and Marine Lipids, in Improved and Technological Advances in Alternative Sources of Lipids, B. Kamel and Y. Kakuda, eds., p. 298, 1994, Aspen Publishers, Inc.

Greene, D.H.S. and Selivonchick, D.P. (1990). Effects of dietary vegetable, animal and marine lipids on muscle lipid and hematology of rainbow trout Oncorhynchus mykiss). Aquaculture, 89,165-182. 

Edible fats and oils (lipids) are derived from plant, animal, and marine sources. Fats and oils differ in that fats are solids at normal room temperature whereas oils are liquids under similar conditions. Lipids are recognized as essential nutrients in both human and animal diets. They provide the most concentrated source of energy of any foods. The caloric value of lipids (9 kcal/g) exceeds twice that of proteins and carbohydrates (4 kcal/g). Lipids not only contribute to flavor, color, odor, and texture of foods, but also confer a feeling of satiety after eating. Lipids also act as carriers of fat-soluble vitamins, supply essential fatty acids, and increase the palatability of foods. Dietary fats are often categorized as visible or invisible ... 

Molecular hydrogen is an important intermediate in the degradation of organic matter by microorganisms in anoxic habitats such as freshwater and marine sediments, wet land soils, and the gastrointestinal tract of animals. In these particular conditions H2 is produced during fermentation of carbohydrates, lipids, nucleic acids, and proteins by anaerobic bacteria and,... 

Lipids from marine products have been studied less frequently. The detection of co-(o-alkylphenyl)alkanoic acids with 16,18 and 20 carbon atoms together with isoprenoid fatty acids (4,8,12-trimethyltetradecanoic acid and phytanic acid) and substantial quantities of bones from fish and molluscs has provided evidence for the processing of marine animal products in vessels [58 60]. C16, C18, and C20 co-(o-alkylphenyl)alkanoic acids are presumed to be formed during the heating of tri-unsaturated fatty acids (C16 3, C18 3 and C20 3), fatty acyl components of marine lipids, involving alkali isomerization, pericyclic (intermolecular Diels-Alder reaction) and aromatization reactions. 

The milks of all mammals contain lipids but the concentration varies widely between species from c. 2% to greater than 50% (Table 3.1). The principal function of dietary lipids is to serve as a source of energy for the neonate and the fat content in milk largely reflects the energy requirements of the species, e.g. land animals indigenous to cold environments and marine mammals secrete high levels of lipids in their milks. 

Marine lipids with their diversity of unsaturated and branched chain acid moieties are a difficult class of materials to analyze. Ruminants (sheep, goats, cows, etc.) have a bacterial "factory" in the rumen which is able to produce branched-chain partially-hydrogenated lipids from ingested plant lipids. These lipids are incorporated into the milk and meat of the animals and eventually into animals which feed upon the ruminants. As a rule animal lipids are highly complex in comparison to plant materials. Although the branched chain materials are usually present in low concentration when compared to the common fatty acid moieties, complete description of these fats requires more sophisticated GC and thus long open tubular columns in tandem with mass spectrometry and computer analysis of the data has become an important approach. Even with a 100-m column, subcutaneous lipids of barley-fed lambs were so complex that prior fractionation with urea adducts was necessary (17). 

Chromarod FID peaks of sterols, diglycerides, monoglycerides, and polar lipids are narrower and sharper than peaks of triglycerides and free fatty acids when analyzed using either method described in this unit (see Basic Protocol and Alternate Protocol). Hydrogenation of total lipids (see Support Protocol) results in much sharper and narrower peaks, which in turn substantially improves the resolution between lipid classes. The accuracy and precision in quantitating lipid classes of vegetable oils and animal fats are expected to be better than those from marine lipids. 

Waxes are common forms of high-energy storage, in the oils of fish and other marine animals. The major lipids of commercial whale oil consist of approximately 65 percent waxes and 35 percent TAG. The lipids of Australian orange roughy (Hoplostethus atlanticus) and dory fish oils are 97.1 and 90.9 percent wax esters, respectively.58 Essentially all the oil in jojoba (Simmondsia chiensis) seed is in wax form. Whale and jojoba oils have been valued for stability in cosmetics and heavy-duty lubrication applications. 

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