Partially hydrogenated fats

One of the building blocks of dietary fats are fatty acid molecules, as shown to the right Every fatty acid molecule consists of a long chain of nonpolar carbon atoms attached to a polar carbon and oxygen unit known as a carboxylic acid. As discussed in Chapter 13, there are two types of fats— those made from fatty acids with no double bonds, and those made from fatty acids with one or more double bonds. Fatty acids with no double bonds are called saturated fatty acids, while those with one or more double bonds are called unsaturated fatty acids. 

So which are better for you saturated or unsaturated fats The answer is that the body needs both to remain healthy. For example, the body uses saturated fats to produce cholesterol, which is 

Saturated fats tend to be solid, while unsaturated fats tend to be liquid. Think about this from the point of view of a food manufacturer of, say, chocolate bars. Your chocolate bars need to be formulated with fats to give them that delicious creamy flavor. If you choose saturated fats, your chocolates will take on more of a solid consistency, which allows you to wrap them so that they neatly display on the grocery store shelf. If you choose the healthier unsaturated fats, however, then your chocolate 

In a trans unsaturated fat, the orientation of the double bond is switched such that the carbon chain 

List the following products in order of inaeasing proportion of trans fats stick margarine, soft tub margarine, butter. 

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Infrared spectra of fats and oils are similar regardless of their composition. The principal absorption seen is the carbonyl stretching peak which is virtually identical for all triglyceride oils. The most common appHcation of infrared spectroscopy is the determination of trans fatty acids occurring in a partially hydrogenated fat (58,59). Absorption at 965 - 975 cm is unique to the trans functionaHty. Near infrared spectroscopy has been utilized for simultaneous quantitation of fat, protein, and moisture in grain samples (60). The technique has also been reported to be useful for instmmental determination of iodine value (61). 

In the past various marine oils were used in biscuits but this practice had now ceased. Most biscuits contain vegetable fats. It was common to use hydrogenated fat in biscuits because vegetable oils were too soft physically and too unsaturated to be stable against oxidation. If an unsaturated fat is hydrogenated until it is completely saturated then a saturated fat results however, if it is only partially hydrogenated a partially hydrogenated fat with several double bonds is produced. 

Partially hydrogenated fats, 10 829 Partially hydrogenated oils, 10 813 Partially hydrolyzed trimethylaluminum (PHT), 16 88... 

This unit describes the attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopic method (AOCS, 1999a AOAC International, 2000), a novel method for measuring the total amount of fat with isolated trans double bonds. It is applicable to natural fats (ruminant fats) and processed fats and oils (partially hydrogenated fats and oils or refined vegetable oils) consisting of long-chain fatty acid methyl esters or triacylglycerols with trans levels >5%, as percent of total fat (AOAC International, 2000). 

In a partially hydrogenated fat, the number of fatty acid isomers is dramatically increased by the appearance of geometrical isomers (i.e., cis and trans configurations) and various positional isomers (i.e., different positions of double bonds within the fatty acid chain). Thus the in-... 

The importance of being able to determine the geometrical isomers of TGs in partially hydrogenated fats can be ascribed to their effect on the physical behavior of the fats, such as their polymorphic behavior and melting properties. 

Fatty acids consist of a hydrocarbon chain with a carboxylic acid at one end. They can be classified on the basis of the length of the hydrocarbon chain (Table 2.2) and whether there are any double bonds. Trivial names of fatty acids such as butyric, lauric, oleic and palmitic acids are in common use in the food industry. A form of short-hand is used to refer to triglycerides where POS is palmitic, oleic, stearic. If the chain length is the same an unsaturated fat will always have a lower melting point. Another classification of fats that is used is in terms of the degree of unsaturation of the fatty acids. Saturated fats are fats without any double bonds. Many animal fats are saturated, but some vegetable fats, e.g. coconut oil, are saturated also. Mono-unsaturated fats include oils like olive oil but also some partially hydrogenated fats. Polyunsaturated fats have many double bonds and include sunflower oil. Because they are... 

Interesterification Interesterification is another process for changing the melting properties of fats and oils. The process represents an alternative to the use of partially hydrogenated fats in manufacturing products of a variety of melting properties. 

It s essential to eliminate unhealthy, acid-forming fats from your diet. You learned about the harmful effects of trans fats in chapter i. Read the labels on packages and avoid anything with trans fats, hydrogenated fats, or partially hydrogenated fats. You ll find this information in the Nutrition Facts table or the ingredient list. 

Akofect. [Karlshamns] Partially hydrogenated fats from soybean or cottonseed oil cocoa butter replacements. 

Trans isomers always occur in oil-fried products because they are formed at high temperatures. The developments in fat hydrogenation with respect to process optinuzation and the selection of catalysts have resulted in a gradual reduction in FA trans isomers in partially hydrogenated fats. The result of complete hydrogenation, in which all bonds of unsaturated FA are saturated with hydrogen, are hardened fats that undergo further modification by interesterification. 

It has been estimated that the daily intake of trans acids (in West Germany) is 4.5 6.4 g per day. About 35-45% of this comes from ruminant fats (biohydrogenation) and the balance from partially hydrogenated fat. Some of the trans acids are deposited in the tissues which may contain about 2% (1.0-4.3%) of these acids. Another study concludes that such acids are harmless if accompanied by an adequate dietary intake of linoleic acid. 

Each hydroperoxide can produce two aldehydes of which the short-chain volatile member is more significant in this context. The other aldehyde is a polyfunctional compound attached to an ester (glyceride) function. Aldehydes produced from natural fats will be complex mixtures because of the large number of hydroperoxides from which they can be produced. This number may be greater still with partially hydrogenated fats because of the large number of double-bonds positions possible in such compounds (Section 10.1). Most of these aldehydes have a very low flavour threshold level so they need be present only at minute levels. For example, the deca-2,4-dienal produced from linoleate 9-hydroperoxide produces a deep-fried flavour at... 

Papaver somniferium, 80 Paper chromatography, 277 Parallel chain planes, 323 Paraquat and lung lipids, 552 Parinaric acid, 11 Parinarium sherbroense, 74 Partially hydrogenated fats, 457 Pea, 488... 

When rats are fed on partially hydrogenated fats the E acids are... 

There is a definite need to analyze all the trans- % isomers since some of the isomers are precursors to CLA. In addition, the complete trans isomer and CLA profiles in milk and meat fats of ruminants provides an excellent indicator of the rumen bacterial state, specifically the content of 1 Of-18 1. A complete trans isomer composition will provide an accurate database to compare the current isomer profile between ruminant fats and partially hydrogenated fats. 

These derivatizations have not been used extensively since the catalysts are generally strong acids that would isomerize CLA. Furthermore, the separation characteristics of these esters, and the method of how the results of esters are integrated with the FAME results, have not been as well documented. Alternatively, some researchers have used a combination of GC columns the total FAME were analyzed on a shorter Carbowax type GC column (25 m), followed by resolution of the 18 1 to 18 3 isomers using a 100 m polar column operated at different isothermal conditions from 170 to 190°C (33,89,91,104,118). Isothermal temperatures between 170 and 190°C maybe appropriate for the analysis of partially hydrogenated fats (100) and specific regions of the milk FA profile, but not for the complete analysis of dairy fats that contain short-chain FA (15,34). In fact the new AOCS official method forTFA analysis (method Ce lh-05) recommends isothermal operation at 180°C, but this method is not suitable for ruminant fats (67). 

Fig. 6 Separation of Irons isomers of a partially hydrogenated fat on a 50 m CP-Sil88 column.

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