chapter  11
Analysis of Neutral Lipids: Unsaponifiable
Pages 36

The lipidic material is constituted mainly of triacylgly-

cerols that are the major components, and numerous

minor compounds of different chemical nature. These

minor components can be divided into glyceridic and

nonglyceridic compounds. The minor glyceridic com-

pounds are di-and mono-acylglycerols, oxidized

triacylglycerols, triacylglycerol polymers, phospholi-

pids, and glycolipids. The nonglyceridic minor com-

ponents are compounds of very different polarity, such

as hydrocarbons, tocols, prenols, aliphatic alcohols,

steroidal alcohols, steroidal aldehydes, steroidal acids,

fatty acids, volatile compounds, pigments, and phe-

nols. Furthermore, esters of fatty acids with short-and

long-chain and steroidal alcohols are present in some

food matrices. For determining the nonglyceridic minor com-

pounds, usually the glyceridic material is eliminated

by saponification. Saponification consists in transform-

ing the glyceridic compounds and fatty esters in soaps,

glycerin, and other alcohols, by heating with a solution

of alkali in ethanol. The subsequent addition of water,

extraction of the aqueous solution with organic sol-

vents, followed by evaporation of the organic solvent

yields a residue called the unsaponifiable matter, which

is constituted of numerous nonvolatile compounds

belonging to several chemical families. Each of these

families can include various classes of compounds;

e.g., hydrocarbons are constituted of alkanes, alkenes,

and terpenic and polycyclic aromatic hydrocarbons.