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 C„H2,tO._. of which formic acid is the first member. The other 

 members of the series which occur in fats are : 



Acetic acid CH3COOH or C,H,0,, 

 Butyric acid C3H7COOH or C4HA 

 Caproic acid C5H11COOH or CMA 

 Caprylic acid CHigCOOH or C^HjA 

 Capric acid aHi<,COOH or C.^^A 

 Laurie acid CnH^gCOOH or C,.^._,0, 

 Myristic acid C,,H,;COOH or C,M.A 

 Palmitic acid Ci,,H,,COOH or CYi..A 

 Stearic acid Ci7H3.,COOH or CigHaA 

 Arachidic acid CiflHaiCOOH or C,oll4o0o 

 Behenic acid C^^H^COOH or C.^B.J0, 

 Another series is the oleic or acrylic series C,iH.>,t_20o of which the 

 members are : 



Tiglic acid CHsO, 

 Oleic acid C]8H340., 

 Elaidic acid CisHgjOo 

 Iso-oleic acid C18H34O., 

 Erucic acid C02H42O0 

 Brassidic acid C02H40O0 



