Vegetable fats, fatty acid composition

Table 3 Typical fatty acid compositions of vegetable oils and animal fats...

The fats and oils standards aim to provide protection in terms of authenticity of the products covered and contain descriptions of each. They also recognize that the fatty acid composition is one of the main ways of identifying and distinguishing one oil/fat from another. Fatty acid specifications for each oil/fat are included as essential composition and quality factors and are reproduced in Tables 8.6 and 8.7. For vegetable oils, it is also recognized that other compositional factors may be used to assist in assessing authenticity—iodine... 

Identification Menhaden Oil can be differentiated from animal fats and vegetable oils by the distinctive significant amount of long-chain C20 and C22 fatty acids. Partially Hydrogenated Menhaden Oil exhibits the following typical composition profile of fatty acids, determined as directed under Fatty Acid Composition, Appendix VII ... 

The vegetable oils and fats can be divided into three groups on the basis of fatty acid composition. The first group comprises oils containing mainly fatty acids with 16 or 18... 

Unlike processed vegetable fat the composition of butter can only be altered by fractionation (typical fatty acid compositions of milk fats are given in Tables 3.5 and 3.6). It is possible to fractionate butter by a number of methods, either using solvents (such as acetone or alcohol) or by vacuum distillation or slow crystallisation. Solvent fractionation can be used to produce well defined fractions but has certain disadvantages ... 

Although Table 1 lists the fatty acid compositions of various lipids, this is not the only or the final arbiter of their classification. As opposed to vegetable fats and oils (other than olive oil), where only one oil is generally identified as originating from an oilseed (e.g., corn oil), a diversity of definitions and specifications is used in the identification of and trade in animal fat products. These often include statements of the allowed limits of any number of quality parameters. 

The density of liquid oils is dependent on their fatty acid composition, minor components, and temperature. An equation taking these into account was developed by Pantzaris (27) using iodine value, saponification value, and temperature. The density of liquid oils is in the range of 0.909-0.921 and for solid fats varies between 0.858 and 0.893. The lower values are for more solid fats such as lard and tallow. In a similar way, the viscosity of various vegetable oils depends on their fatty acids. Generalized methods have been developed that allow calculation of density and viscosity of different oils. Coupland and McClements (28) and Fisher (29) have related viscosity and density, refraction, surface tension, and other physical properties. Viscosity of fats and oils also depends on the temperature. 

Betapol , a human milkfat substitute produced by Loders Croklaan (Wormerveer, the Netherlands), is produced by interesterification of vegetable oils in which the component TAGs have been modified to more closely resemble those found in breast milk. This product closely mimics the specific structure and fatty acid composition of human milkfat and resembles breast milk in terms of its nutritional value and high content of palmitic acid at the sn-2 position than other milkfat substitutes. In addition, the use of Betapol in infant formula can lead to improved mineral and fat absorption and less calcium soap formation within the intestinal lumen resulting in softer stools. 

TABLE 8. Fatty Acid Composition of Common Feed Animal Fats, Fish Oils, and Vegetable Olls. ... 

One common feature of the mediterranean dietary habit is the use of olive oil as fat source in place of animal fat typical of Northern European and USA diets. As compared to other vegetable oils, olive oil is charaeterized by the peculiar composition of the tryglieeride fraction and by the phenolic and volatile constituents which affect the organolectic properties. Olive oil is rich in monounsaturated fat (56-84% of oleic acid), contains 3-21% of the essential linoleic aeid [3], is low in tocopherols [4,5] and therefore the presence of phenols is important to mantain the anti-oxidative stability. Several articles [1,2,6] reviewed the reasons why olive oil should be preferable to other dietary fat, paying particular attention to the fatty acid composition. Oleic acid is antithrombotic compared to saturated fatty acids [7]. Monounsaturated and polyunsaturated fats reduced low density lipoproteins (LDL) levels. 

The physiological effects of vegetable oil are based on their fatty acid composition. Current US dietary guidelines recommend that diets contain less than 30% calories from fat, of which less than 10% is from saturated fat, 10-15% from monounsaturated acid, and 10% from polyunsaturated acids. The primary concerns with fatty acid consumption relate to two chronic diseases—coronary heart disease (CHD) and cancer. Research has shown that high levels of dietary saturated fatty acids are related to increased CHD and that dietary modification can lower plasma cholesterol. Consequent changes in cholesterol level can be predicted by the following relationship (Hegsted et al. 1993). 

The tocols (tocopherols and tocotrienols) are the most important class of antioxidants naturally present in vegetable oils and fats. Animal fats only contain trace amounts and this is reflected in their much lower oxidative stability compared with vegetable oils of equivalent degree of unsaturation. Bailey (1951, pp. 61-62) noted many years ago that at high levels tocols can act as prooxidants and that vegetable oils seem to contain near optimum levels for the their fatty acid composition. 

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