The Determination of Linoleic Acid in Milk Fat

Until recently, when the photoelectric spectrophotometer came into general use as an aid in fat analysis, it has been practically impossible to obtain accurate data on the amounts of the unsaturated acids in fats. Most of the naturally occurring fats do not possess chromophores but possess structures which may be altered by chemical means to produce groups which absorb radiant energy. For example, linoleic acid possesses a diene grouping and when treated with alkali forms an isomer containing a conjugated double bond, which structure causes an absorption of light in a region of the ultraviolet spectrum. The intensity of the absorption may be used as a basis for measuring the amount of linoleic acid present in a fat.