Prof. J.P.N. Mishra
Natural fats are made of one molecule of glycerol and one or more than one fatty acid molecules. If three fatty acid molecules are bonded to a single glycerol, a triglyceride is formed. Two fatty acids and a glycerol form a diglyceride, and one fatty acid and a glycerol form a monoglyceride.
The fatty acids may be saturated or unsaturated. As shown in Fig. 1-10 that one of the fatty acids has single covalent bonds between all its carbon atoms. Each of these carbons is then bonded to the maximum number of hydrogen; this is a saturated fatty acid, meaning saturated with hydrogen. The other fatty acids shown have one or more (poly) double covalent bonds between their carbons and less than the maximum number of hydrogen; these are unsaturated fatty acids. Many triglycerides contain both saturated and unsaturated fatty acids, and though it is not as precise, it is often easier to speak of saturated and unsaturated fats, indicating the predominance of one or the other type of fatty acid.
Saturated fats are often in solid form, while unsaturated fats are often in liquid form. Saturated fats tend to be found in animal foods such as beef, pork, eggs, and cheese, but palm oil and coconut oil are also saturated. Unsaturated fats are present in other plant oils such as corn oil, sunflower oil, and safflower oil, but certain fish oils are also unsaturated, and even pork contains unsaturated fatty acids. Unsaturated fats may be changed to saturated fats in order to give packaged foods a more pleasing texture or taste, or to allow them to be stored longer without refrigeration (a longer shelf life). These are hydrogeriated fats (meaning that hydrogen have been added), also called trans fats. Trans fats contribute significantly to atherosclerosis of arteries, that is, abnormal cholesterol deposits in the lining that may clog arteries, especially the coronary arteries of the heart. Triglycerides and cholesterol are transported in the blood in combination with proteins. Such molecules made by the small intestine are called chylomicrons. Those made by the liver are called lipoproteins and are categorized by their density, which reflects the proportion of protein to cholesterol.
