OLIVE OILS AND HEALTH 36 1.1 ANIMAL AND VEGETABLE FATS General aspects and concepts Fats are non-soluble substances in water of differing nature which have the fatty acids as a common pattern. Most fatty acids are attached to glycerin forming triglycerides or triacylglycerides. They are made up of a molecule of glycerin (or glycerol) and three molecules of fatty acids, the major components of fat. They also have minor compounds such as phospholipids and sterols (Figure 1.1). The biochemical term lipids, a synonym of fats, is often used when describing their metabolism in the body. Figura 1.1: Clasificación de lípidos SIMPLE LIPIDS: Triglycerides COMPOUND LIPIDS: Phospholipids DERIVEDLIPIDS: Those released during the hydrolysis of simple and compound lipids Figure 1.1: Lipid Classification. Classification According to their characteristics at room temperature (around 20ºC), fats can be classified as liquid or solid. Liquid fats are called oils and the solid ones butters, lard, or tallows. Butters is soft and melts around 37ºC whilst lard or tallow has both more consistency and a higher melting temperature. Oils and lard are composed almost totally of fat whilst butter contains around 80%, the rest being mainly water. Margarine and other fat products for spreading or for different applications may present a lower fat content. According to their origin, fats are classified as vegetable, animal, or transformed. The fat content of vegetables is generally low with the exception of those defined as oily (e.g., olives, nuts, soy, avocado), and cocoa and its derivatives. The oth-
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