Tuesday, May 1, 2012


Fats and oil are water-insoluble substances of plant or animal origin which consist predominantly of glyceryl esters of fatty acids, or triglycerdes. They constitute one of the three main kinds of foodstuffs {carbohydrate, protein, and fat } and are distributed in nature. Common usage considers as ""fats" treglycerides that are solid or senisolid at room temprature and as "oils" triglycerides that are liquid under tge same conditions. Actually, the distinction is not clear-cut ; therefore , the term "fats" will be used in the chapter to coper glycerides regardles of their physical state .
    Treglycerides contain approximately 95% fatty acid  and 5% glycerol, combined as esters.Treglycerides have the general formula [1]. If  R= R` = R", the treglycsrides can be named from the parent acid by means of the termination "in" thus .for acetic acid [R= R` = R" =CH3] the triglycerides is triacetin.The acids in the fats are fatty acids [qv], wgich are long-chain aliphatic acids,both saturated and unsaturated.tristearin and tripalmitin are examples of fatd that contain onlu one fatty acid ; a structure such as [2] can be referred to as sym-oleodipalmitin.
     H                                                                        H                                      
H-C-00CR                                                         H-C-00C[CH2]14CH3

H-C-00CR`                                                        H-C-00C[CH2]1CH=CH[CH2]1CH3

H-C-00CR"                                                        H-C-00C[CH2]14CH3    

     H                                                                        H

Waxes [qv] differ from fats in that they are fatty acid esters of certain  higher monohydrie alcohols rather than glycerol, wool grease or fat,also called degras,is chiefly a wax, as is also sperm oil.
Because the fatty acid radicals constitute the greater part of the glyceride molecule.and also the reactive portion, the chemical and physical properties of or fat are determined largely by the properties of its component fatty acids . In general , fats become progressively higher melting and more easily solidified as the average molecular weight of the fatty acids increases and as their average unsaturation [number of double bonds] decreases, Fatty oils are sometimes called fixed oils to distinguish them from volatile, ethereal, or essential oils.
    Naturally occurring fats contain minor amounts of soluble impurities such as pigments and sterols. These are removed to some extent during processing, Fats also contain small quantities of phospholipids [lecithin, cephalin ,and sphingomyelin] in which glycerol,fatty acids, phosphorie acid ,and a nitrogen  base are combined. Associated with phospholipids are glycolipids which are carbohydrate fatty acid compouds containing nitrogen but no phosphoric acid.Because of their occurrence in nerve tissue,particularly in the brain ,they are referred to as cerebrosides.
       In the human diet ,large quantities of rat are consumed as natural fatty foods and many edible prepared fat products. Fat are the most concentrated source of energy in the diet, yielding 9,3 kg-cal/g as compared to 4,1 kg-cal/g from protein and carbohydrates . They are also important sources of  oil soluble vitamins and of certain essential fatty acids.
      The considerably smaller [ about 1/3 of the total ] technical or nonedible use of fat is based  mainly upon  the property of  the more unsaturated members of polymerizing to from elastic but durable proteetive coatings.and the long chain character of the fatty acids , which confers survace activity upon many of their  derivatives .In the manufacture of soap as well as of many other surface-active materials, fats are important not as such but as a sources of fatty acids . Where the fatty acids alone are utilized ,glycerol is valuable by product. In certain industryal applyications and for edible use are well , the lubricating or plasticizing  properties of fats or fatty acids are important .

source: K.R Ericson and H.D  Van Wagenen  The procter & Gamble Company 



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