Table 4.2 in your textbook contains the fatty acid composition of several common
ID: 705639 • Letter: T
Question
Table 4.2 in your textbook contains the fatty acid composition of several common fats and oils. Select one of the oils in the table and discuss the following points (both):
1. What is the effect of partial hydrogenation (does not proceed to 100% saturated fatty acids) on the fatty acid composition of the oil. Identify the fatty acids that would be formed during the hydrogenation process. How is the melting point and stability of the oil to lipid autoxidation reactions altered during hydrogenation?
TABLE 4.2 Fatty Acid Composition (%) of Common Foods ?9 18:2 ?9 18:3 ?9 20.5 ?5 22:6 ?4 Total Sat'd 4:0 6:0 8:0 10:0 12:0 14:0 16:0 16:1 ?9 18:0 18:1 Food 16.2 0.6 9.2 0.9 7.8 13.7 1.2 2.5 71.1 10.0 1.9 Olive Canola Corn Soybean Linseed Coconut Cocoa Butterfat Beef fat Pork fat Chicken Atlantic Salmon 64.1 18.7 14.4 15.0 9.5 91.9 60.4 62.7 50.6 38.8 12.2 0.1 2.2 27.5 $7.0 0.1 11.0 0.1 4.0 23.4 53.2 47 19.9 159 $2.7 4.8 2.5 6.5 0.1 25.8 0.3 34.5 35.3 1.5 2.9 2.9 0.5 8.06.4 48.5 17.6 8.4 19 12.5 28.2 0.5 3.8 2.3 .1 2.0 3.1 11.7 26.2 0.1 3.3 25.5 0.1 1.5 24.8 0.2 1.3 23.2 6.5 6.4 41.6 18.9 21.6 38.7 12.3 45.1 0.1 9.9 0.1 1.3 31.1 21.4 0.6 1.9 11.9 23.4 5.0 15.9 6.3 2.5 Only the major faty acids in tese productsae is d. Al fay acicompsitions are adapted from White 193] with the exception of Atlantic Salmon,which is adaped from Only the major fatty acids in these products are li Ackman [1].Explanation / Answer
From the given table i am selecting Olive oil as a study sample. From the table 16:0 (Palmitic acid), 18:1(Oleic acid), 18:2 (Omega-6), 18:3 (Omega-3)
(1) Hydrogenation: To treat or combine chemically an unsaturated compound [here it is fatty acids; MUFA's(Oleic acid), PUFA's (Omega-6 or Linoleic acid, Omega-3 or Alpha-linoleic acid)] in the presence of a catalyst Raney-Nickel or other suitable catalyst listed. (2) For partial hydrogenation of Oleic acid it requires 2 H (one double bond) required resulting in formation of saturated fatty acid(stearic acid; 18 C), similarly for Omega-6 it requires 4 H (2 double bonds cis geometry) to form saturated fatty acid (stearic acid; 18 C), for Omega-3 it requires 6 H (3 double bonds in Cis geometry) to form saturated fatty acid (stearic acid; 18 C). (3) Since geometry of double bonds in omega-6 and omega-3 are Cis form in its natural state(prior to partial hydrogenation) molecules donot stack very well, Intermolecular interactions are much weaker than saturated fatty acids formed after(partial hydrogenation), therefore the Melting points are much lower for Unsaturated fatty acids like Oleic, Omega-6, Omega-3. Melting point of corresponding saturated fatty acids formed after partial hydrogenation are much higher(due to change in geometry to trans from). (4) After the partial hydrogenation the stability of the oil for lipid Auto oxidation increases and its Melting point increases. (5) Interesterification: Interesterification of triglyceride oils can be defined as the exchange of fatty moieties between different triglyceride molecules also ofen called ester interchange. (6) On the triglyceride back bone on the three fatty acid ends there is possibility of forming random inter esterification. with Oleic acid moiety, Omega-6 moiety, Omega-3 moiety. resulting in formation of mixture of esterified fatty acids (7) Interesterification needs catalysts , Alkaline (chemical) or Enzyme (biochemical). (8)In this case Interesterification results in decrease in Melting point decreases stability of oil to autooxidation.
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