COMPOSITION OF FREE FATTY ACIDS IN HIGH ACID GHEE
By T. M. PAUL, V. R. BHALERAO, C. P. ANANTAKRI SHNAN AND M. C. RANGASWAMY, Imperial Dairy
Research Institute, Bangalore
(Received for publication on 23 September 1946)
C LARIFIED butterfat is commonly known as ghee in India and it is a very popular article of diet
among the people. More than 50 per cent of all the milk produced in the country is utilized
for the manufacture of ghee. Possibly due to faulty methods of manufacture, collection and storage
conditions, very often ghee containing considerable amounts of free fatty acids, are come across in
the market. These are often-times condemned as unfit for human consumption. During the course
of an investigation into the causes of the development of acidity in ghee, it was thought interesting
to know the nature of the free fatty acids present in ghee. Therefore, attempts were made to separate
the free fatty acids from high acid ghee and to study their chemical composition.
In India butter is mostly prepared in small amounts and accumulated for various lengths of
time before converting into ghee. It is possible that acidity is produced during this storage period.
It was found that butter prepared from raw milk developed acidity in a shorter time compared to
butter prepared from boiled milk. Therefore, butter was prepared from raw cow's milk by the
indigenous method of souring the milk by addition of small amount of starter and then churning it.
This butter was kept at room temperature for about a month. By that time the butter had developed
about 20.0 per cent acidity calculated as oleic acid. The butter was then melted and converted into
ghee by the 'boiling off' method. About 300 gm. of this ghee was set apart to study the chemical
composition. This is referred to as Sample I. The rest of the ghee was boiled with twice its weight
of 95.0 per cent alcohol, and the free fatty acids neutralized with dilute alkali. After separating the
residual fat (Sample II), as far as possible, the soap solution was distilled to remove most of the
alcohol. The alcoholic residue was diluted with water and extracted with successive portions of
ether to ensure the removal of all fat from the soap. It was then acidified with hydrochloric acid
and the liberated fatty acids were extraced exhaustively with ether.
The ether extracts were washed free from acids and the washings were collected (Solution K).
The washed ether extracts were dehydrated, filtered and solvent (Solution Y) distilled off. The
fatty acids (Sample III) were then converted into methyl esters by refluxing for one hour with 1,000 ml.
of methyl alcohol containing 3 sulphuric acid. Most of the alcohol was then distilled off, the distillate
made up to a known volume (Solution W) and preserved for subsequent analysis. The residue was
cooled, transferred to a separating funnel and diluted with water. It was extracted exhaustively
with ether. The ether extracts were washed free from acid. The washings were then mixed with
solution K, made alkaline with KOH, and the volume was reduced at atmospheric pressure. The
residue was acidified and steam distilled and the distillate (Solution X) titrated against 0.1 N alkali
and expressed as methyl butyrate. The washed ether extracts were dehydrated filtered and solvent
distilled off. (The distillate was mixed with solution Y and made to known volume). Aliquots
were then taken from solution W and Y distillates and saponified with potash and the results expressed
as methyl butyrate. Total of these determinations gave the amount of C 4 acid originally present
in the fat. The methyl esters of the fatty acids now obtained and the methyl esters prepared from
samples I and II were subjected to detailed ester fractionation in an EHP column according to the
method of Hilditch as modified by Smith and Dastur [1938]. The results obtained are presented
in Tables I to VI. The analytical characteristics of Sample I and II are as follows:
Sample I
Sample II
Melting
Point
33.2
41.8
B.R.
Reading
at 40°C.
40.2
40.8
Sap.
Equivalent
246.8
251.1
Iodine
Value
29.55
21.38
R.M.
25.85
21.96
Polenske
1.65
1.45
Free Fatty
acids as oleic
acid. (per-
centage)
19.31
0.02
95
H