3. Read the text. Fats and oils

Lipids are the compounds that can be extracted from cells and tissues by non-polar organic solvents. They are the water insoluble components derived from plants and animals.

The classification is rather unusual, since lipids have no characteristic chemical or structural properties. The only common thread connecting the compounds in this group is their method of isolation and similar biogenetic origins, in many respects the lipid classification is a catchhall for many diverse and inbiological molecules.

Fats and oils contain carbon, hydrogen and oxygen and they are the most esters of long-chain carboxylic acids. Because they can be formed from excess carbohydrates in living organisms, fats and oils function as a major storehouse of energy. Fats are solid triglycerides, whereas oils are liquids at typical room temperature. It is common practice to call all viscous organic liquids oils.

The fatty acids of which fats and oils are composed are usually nonbranched molecules containing from 14 to 22 carbon atoms. Interestingly, the> almost always possess an even number of carbon atoms — a fact that is related to their biosynthetic origin. Both saturated and unsaturated fatty acids are commonly recovered from the hydrolysis of lipid materials.

Triglycerides may be esters of identical or different fatty acids. Natural fats and oils are mixtures of glycerol esters in which one or two fatty acid components usually predominate. For example, olive oils contain a high percentage of oleic acid and corn oils are composed principally of linoleic and oleic acids. These are the common unsaturated oils used in food preparation. Butter contains many fatty acids, most of which are saturated. Solid triglycerides (fats) normally have a higher percentage of saturated fatty acid. It's the complete hydrolysis that provides the component fatty acids plus glycerol.

Saponification of fats and oils is the industrially important method of making soap. The enzyme lipase hydrolyzes during the digestive process.

Urn saturation in fats and oils is usually determined by quantitative addition of iodine to the double bond. Hydro- genation of the double bonds of unsaturated oils is the industrial method for converting oils 10 fats. It’s oxidation associated with the double bond that is of commercial and biological importance. Controlled oxidation of oils is the problem in the long-term storage of foods; for it is an important pathway of biological degradation.

3. Speaking.

1. Запитання до тексту

1. What elements do fais and oils contain? 2. What is the main fonction of fats? 3. What are fatty acids? Can you name .some of them? 4. How can fatty acids te obtained? 5. What oils але used in food preparation? 6. What is saponification? 7. Why is oxydation of commercial and biological importance? 8. What properties of fats and oils do you know?

2. Заповніть пропуски словами, поданими в дужках (enters; storehouse; converting; insulator; saponification):

I. fats are a major ... of energy. 2. Triglycerides may be ... of fatty acids. 3. The industrial method of making soap is ... of fats and oils. 4. The adipose tissue is a very good ... for animals. 5. Hydrogenation is the industrial method for ... oils to fats.