Types of Fat
General Chemical Characteristics
Fatty acids are composed of a carboxyl group, a series of hydrocarbons that can be saturated (—CH2- CH2-) or unsaturated (—CH=CH-) with a methyl group (CH3) at the other end. They differ from each other according to their chemical structure including the number of carbon atoms, the degree of unsaturation, location of double bonds, and the configuration of their carbon structure. Biological systems contain only carbon-carbon bonds in the cis-configuration, although industrial food processing can produce carbon-carbon bonds in the trans-configuration. In the body fatty acids are transported as fatty acids that are carried by plasma protein albumen or transported as triglycerides (glycerol with ester linkages to three fatty acids) in either chylomicrons or very low density lipoproteins (VLDL).
Saturated Fatty Acids
Saturated fats contain no double bonds. Major food sources include red meat, poultry, fish, dairy foods (milk, eggs, cheese, and butter), and tropical oils (palm and coconut oil). Butter is an example of a food product rich in saturated fats and solid at room temperature and less solid when the summer kitchen temperature is 80 °F. In the human body, cell membranes also need some degree of rigidity and hence saturated fatty acids in the plasma membrane prevent cells from being too flexible (fragile). For this reason plants (e.g., the palm tree) and fish (e.g., snapper) that thrive in warmer growing environments typically contain more saturated fatty acids.