Nonglyceride Components of Edible Oils and Fats. 1. Chemistry and Distribution

Dietary fats and oils are essentially glycerides of fatty acids (triglycerides), which account for 90% to 98% of their mass. The remaining 2% to 10% consists of fatsoluble phytochemicals derived from oil-bearing seeds, nuts, or fruits. These nonglyceride components of fats and oils represent a wide range of chemical classes, such as sterols, terpene alcohols, tocopherols, hydrocarbons, long-chain alcohols including waxes, carotenoid pigments, and sulfur- and nitrogen-containing flavor compounds. Each of these classes of chemicals consists of a number of different compounds. Their number and type and the quantity present vary from one oil to another. Modern analytical tools developed in recent decades have enabled separation and identification of the individual chemicals of each class in a number of oils. The nonglyceride chemical components of oils pass into the unsaponifiable fraction as such or in a modified form. There is still a gap in our knowledge concerning the identity and nature of several of these chemicals in the nonglyceride components, particularly in some of the unconventional edible oils. Earlier, these nonglyceride components were considered adventitious chemicals. For the past two decades, however, it has been recognized that many of them have nutritional and physiological functions that have been proved by animal and human studies to be useful in preventing noncommunicable diseases and promote health. The nonglyceride components of edible oils (i.e., palm, rice bran, and sesame oils) are particularly rich in such health-promoting chemicals.