CHAPTER VI 



THE FATS AND LIPASES 



A FAT may be defined as an ester or glyceride of a fatty acid. Just 

 as an inorganic salt, such as sodium chloride, is formed by the reaction 

 of hydrochloric acid with sodium hydroxide, so a fat is formed by the 

 reaction of the trihydric alcohol, glycerol, and a fatty acid. 



The word fat is not a familiar one in botanical literature, the term 

 oil being more commonly used. It is generally met with in connexion 

 with the reserve products of seeds. The oils of seeds are, however, true 

 fats. The term oil may be misleading to some extent, because a fat 

 which is liquid at ordinary temperatures is usually spoken of as an oil, 

 and yet there are also many other substances, of widely differing chemi- 

 cal composition, which have the physical properties of oils, and which 

 are known as such. 



Most of the vegetable fats are liquid at ordinary temperatures but 

 some are solids. 



The best-known series of acids from which fats are formed is the 

 'series CnH^Oa of which formic acid is the first member. The other 

 members of the series which occur in fats are : 



Acetic acid CH 3 COOH or C 2 H 4 O 2 

 Butyric acid C 3 H 7 COOH or C 4 H 3 O 2 

 Caproic acid C 5 H n COOH or C 6 H 12 O, 

 Caprylic acid C 7 H 15 COOH or C 8 H 16 O 2 

 Capric acid C 9 H 19 COOH or QoHjA 

 Laurie acid CnH^COOH or C 12 H 24 O 2 

 Myristic acid C^H^COOH or CuK^A 

 Palmitic acid C 15 H 31 COOH or C 16 H 32 2 

 Stearic acid C 17 H M COOH or 

 Arachidic acid C^H^COOH or 

 Behenic acid C^H^COOH or C^H^O, 



Another series is the oleic or acrylic series CnH^.aOa of which the 

 members are : 



Tiglic acid C 5 H 8 O 2 

 Oleic acid C 18 H M O a 

 Elaidic acid C^H^O, 

 Iso-oleic acid C 18 H^O 2 

 Erucic acid 

 Brassidic acid 



