Butter fatty acids

Table 9.5 Fatty acyl composition of triacylglycerols from Candida curvatalApiotrichum curvatum wild type (WT) strain, an unsaturated fatty acid auxotrophic mutant (Ufa 33), a revertant mutant (R22.72) and a hybrid derived from Ufa 33 (F33.10) compared to cocoa butter fatty acids...

Animal fats and vegetable oils are triacylglycerols, or triesters, formed from the reaction of glycerol (1,2, 3-propanetriol) with three long-chain fatty acids. One of the methods used to characterize a fat or an oil is a determination of its saponification number. When treated with boiling aqueous KOH, an ester is saponified into the parent alcohol and fatty acids (as carboxylate ions). The saponification number is the number of milligrams of KOH required to saponify 1.000 g of the fat or oil. In a typical analysis, a 2.085-g sample of butter is added to 25.00 ml of 0.5131 M KOH. After saponification is complete, the excess KOH is back titrated with 10.26 ml of0.5000 M HCl. What is the saponification number for this sample of butter ... 

A USDA report indicates that between 1967 and 1988, butter consumption remained stable at 2 kg per capita, margarine dropped from 5.1 to 4.7 kg, and measured total fat intake per day dropped from 84.6 to 73.3 g (14). This study also projects that the reduced consumption of tropical oils is only temporary and will return to former use levels, possibly even higher. One reason for this projected rise in tropical oil consumption is the knowledge of the beneficial effects of medium-chain length acids high in lauric oils. There is a keen interest in omega-3 fatty acids, as well as linoleic acid, contained in fish oils. 

There are physical—chemical differences between fats of the same fatty acid composition, depending on the placement of the fatty acids. For example, cocoa butter and mutton tallow share the same fatty acid composition, but fatty acid placement on the glycerin backbone yields products of very different physical properties. 

Sohd fats may show drastically different melting behavior. Animal fats such as tallow have fatty acids distributed almost randomly over all positions on the glycerol chain. These fats melt over a fairly broad temperature range. Conversely, cocoa has unsaturated fatty acids predominantly in the 2 position and saturated acids in the 1 and 3 positions. Cocoa butter is a brittle sohd at ambient temperature but melts rapidly just below body temperature. 

Cocoa butter is composed mainly of glycerides of stearic, palmitic, and oleic fatty acids (see Eats AND FATTY oils). The triglyceride stmcture of cocoa butter has been determined (11,12) and is as foUows ... 

Cocoa butter substitutes and equivalents differ greatly with respect to their method of manufacture, source of fats, and functionaHty they are produced by several physical and chemical processes (17,18). Cocoa butter substitutes are produced from lauric acid fats such as coconut, palm, and palm kernel oils by fractionation and hydrogenation from domestic fats such as soy, com, and cotton seed oils by selective hydrogenation or from palm kernel stearines by fractionation. Cocoa butter equivalents can be produced from palm kernel oil and other specialty fats such as shea and ilHpe by fractional crystallization from glycerol and selected fatty acids by direct chemical synthesis or from edible beef tallow by acetone crystallization. 

Table 14. Fatty Acid Composition of Raw Cocoa Beans and Cocoa Butter ...

Dairy products (see Milk and milkproducts) have been staple items of the diet for many centuries, and have long been the target for imitation. The development of nutritional guidelines emphasizing the need to reduce total dietary fat, dietary cholesterol [57-88-5] C2yH4 0, and saturated fatty acids (see Fats and fatty oils Fat substitutes), has increased the interest in imitation dairy foods. However, with the exception of butter and cream the market penetration of dairy substitutes has been limited. 

Oils, Nitrated. See under Fats, Fatty Oils, Tallows, Butters, Waxes and Fatty Acids in Vol 8, F8-L to F9-L... 

Stearic acid is the most common of the long-chain fatty acids. It is found in many foods, such as beef fat and cocoa butter. It is widely used as a lubricant in soaps, cosmetics, food packaging, deodorant sticks, and toothpastes. It is also a commonly used softener in rubber. 

Small amounts of trans-unsamrated fatty acids are found in ruminant fat (eg, butter fat has 2-7%), where they arise from the action of microorganisms in the rumen, but the main source in the human diet is from partially hydrogenated vegetable oils (eg, margarine). Trans fatty acids compete with essential fatty acids and may exacerbate essential fatty acid deficiency. Moreover, they are strucmrally similar to samrated fatty acids (Chapter 14) and have comparable effects in the promotion of hypercholesterolemia and atherosclerosis (Chapter 26). 

The main difference between oils and fats is that oils are liquid at room temperature and fats are solid at room temperature. Oils, such as olive oil or corn oil, usually come from plant sources and contain mainly unsaturated fatty acids. Fats, such as butter and lard, contain an abundance of saturated fatty acids and generally come from animal sources. 

This specification is for butter oil, which is butter with the water removed. The free fatty acid limit is to detect lipolytic rancidity while peroxide value specification is to limit oxidative rancidity. The copper limit arises because copper catalyses the oxidation of fats. The absence of neutralising substances is to prevent a high titration for free fatty acids being covered up by the addition of alkali. 

Fig. 21.16. 513C values for the Ci6 o and Ci8 0 fatty acids extracted from the Roman cream, compared with confidence ellipses (la) corresponding to those from modern cow, sheep, and pig adipose fat and sheep and cow butter fat (reference 513C values are adjusted for post-industrial Revolution effects of fossil-fuel burning analytical precision + 0.3%). (Reprinted/redrawn from Nature, 432, 35-36, Copyright 2004, Nature Publishing Group, with permission.)... 

Odd-numbered fatty acids do occur naturally with carbon numbers between 3 and 19. Those with carbon numbers 15 to 19 are present in large amounts in certain species of fish and bacteria. Even-numbered fatty acids, 4 to 10, are mainly found in milk and butter fats. 

The solubility of C60 and C70 in a series of vegetable oils, namely olive, sunflower, peanut, soybean, linseed and castor oil, has been determined quantitatively spectrophotometrically. Additionally, the solubility of C60 and C70 has been determined quantitatively in the methyl esters of brassica oilseed and only qualitatively in molten cow butter, molten stearic acid and molten behenamide. The experimental results show that the solubility of fullerenes appears to be dependent on the unsaturation level of the fatty acids composing the vegetable oils being lower in oils with higher unsaturation level. The solubility has been found dependent also on the polarizability parameter of the vegetable oils. 

The common fatty acids have a linear chain containing an even number of carbon atoms, which reflects that the fatty acid chain is built up two carbon atoms at a time during biosynthesis. The structures and common names for several common fatty acids are provided in table 18.1. Fatty acids such as palmitic and stearic acids contain only carbon-carbon single bonds and are termed saturated. Other fatty acids such as oleic acid contain a single carbon-carbon double bond and are termed monounsaturated. Note that the geometry around this bond is cis, not trans. Oleic acid is found in high concentration in olive oil, which is low in saturated fatty acids. In fact, about 83% of all fatty acids in olive oil is oleic acid. Another 7% is linoleic acid. The remainder, only 10%, is saturated fatty acids. Butter, in contrast, contains about 25% oleic acid and more than 35% saturated fatty acids. 

The effects of dietary lipids on human health are complex. However, in general dietary terms, monounsaturated fatty acids are considered to be more healthful than saturated fatty acids. A lot of people, concerned about their health, have decreased their dietary intake of butter in favor of olive oil or vegetable oils. 

---