FATS AND OILS Introduction INTRODUCTION • Fats and oils belong to naturally occurring substances called lipids. • Lipids are large and diverse group of natural-occurring organic compounds defined as the biomolecules which are insoluble in water and highly soluble in non-polar solvents i.e. ether, benzene. Fats & oils contain mixture of fatty substances, lipids called TRIGLYCERIDES. Lipids are of two types 1. SIMPLE LIPIDS – They do not have ester linkages & cannot be hydrolysed. Such as fats, oils, waxes. 2. COMPLEX LIPIDS – They contain ester linkages, these ester linkages can be hydrolyzed to give small molecules. Such as cholesterol & steroids. Triglycerides • Triglycerides are made up of long chain of fatty acid & glycerol. Triglycerides • The union of one molecule of glycerol and one molecule of fatty acid forms a Monoglyceride. • If two fatty acids are attached to glycerol, it is called a Diglyceride. • If three fatty acids are attached to glycerol, it is a Triglyceride. • When three fatty acids in a triglyceride are of the same kind, the fat is a Simple Triglyceride. • When three fatty acids in a triglyceride are different, the fat is a Mixed Triglyceride. In a mixed glyceride, more than one kind of fatty acids are present. Basic difference between Fats and Oils FATS OILS • Fats are solid at room temperature. • Fats are usually come from animal source. • Butter, Ghee are mainly rich sources of fat. • Oils are liquid at room temperature. • Oils are generally come from plant source. • Oilseeds and nuts are rich sources of oils. Fatty Acids • They are building block of fats and oils. About 40 different fatty acids are known naturally. They are long chain carboxylic acids (usually even number of carbon atoms). Classification of Fatty acids Fatty acids differ from one another in their chain length (the number of carbon atoms in each molecule) and the degree of saturation. 1. On the basis of carbon chain length (short, medium and long chain fatty acids) 2. On the basis of degree of saturation. (saturated, monounsaturated and polyunsaturated) 3. On the basis of requirements (Essential and Non-essential fatty acids). On the basis of carbon chain length • Short chain fatty acids (SCFA): They have a chain length of 6 or fewer carbon atoms), examples of which include acetic acid found in vinegar and butyric acid. • Medium chain fatty acids (MCFA): They have a carbon chain length of 6–12 carbon atoms. Examples include caproic acid in butter and lauric acid in palm kernel and coconut oil. • Long chain fatty acids (LCFA): They have a chain length of 13 to 21 carbon atoms and include palmitic and stearic acid found in lard and beef tallow respectively. Oleic acid and linoleic acid (18 carbon atoms) are also long chain fatty acids. They are found in olive and corn oils respectively. Continued.. • Very long chain fatty acids (VLCFA): They are fatty acid with 22 or more carbons. VLCFA's can represent up to a few percent of the total fatty acid content of a cell. Examples include lignoceric acid (C24:0) found in peanut oil. Table : Fatty Acids with number of carbon No. of Carbons Saturated Fatty Acid 4 Butyric 6 Caproic 14 Myristic 16 Palmitic 18 Stearic Unsaturated Fatty Acid 18 Oleic 18 Linoleic On the basis of degree of saturation • Saturated Fatty Acids – These fatty acids contain single bond between them. Examples include stearic acid, palmitic acid etc. • Unsaturated Fatty Acids – These fatty acids contain one or more than one double bond between them. They are of two types – Monounsaturated fatty acid and Polyunsaturated fatty acid. • Fatty acids which contain only one double bond are called monounsaturated fatty acids (MUFA) eg. Oleic caid and which contain more than one double bond are called polyunsaturated fatty acids (PUFA) eg. Linolenic acid and linoleic acid. Differences between MUFA and PUFA Monounsaturated Fatty Acid • Fatty acids that have one double bond in fatty acid chain. • Occur in olive,sesame, and canola oil. • Have a higher melting point. • Lower the LDL cholesterol &total cholesterol & increase the production of HDL cholesterol. • Examples : Palmitoleic acid , oleic acid, and cis-vaccenic acid. Polyunsaturated Fatty Acid • Fatty acids that have more than one double bond. • Occur in sunflower seed oil, corn oils. • Have a lower melting point. • Reduce the serum cholesterol levels and the production of both LDL and HDL cholesterol. • Examples : Omega-3-fatty acids and omega-6- fatty acids. On the basis of requirements • Essential fatty acids: They are fatty acids which are required for the normal functioning of body but they cannot synthesized by human body. Their deficiency causes diseases so, we have to take them externally. Alpha-linolenic acid (an omega-3 fatty acid) and linolenic acid (an omega-6 fatty acid) are essential fatty acids for humans. • Non-essential fatty acids: They are fatty acids which can be synthesized or formed in our body through diet which we consume. we need not to supply them externally. All fatty acids except essential fatty acids are nonessential fatty acids. Such as lauric, myristic fatty acids.
