2.2.1 Iodine Value
The traditional method of determining the average number of double bonds in fat or oil makes use of carbon tetrachloride as solvent. This parameter was determined according to the AOCS official method Cd 1-25. 5g of PFAD sample was put in a conical flask which contained 30ml of carbon tetrachloride, and a solution of 10% potassium iodide. The mixture was kept in the dark for about 30mins and the liberated iodine was titrated against 0.1N standard sodium thiosulfate solution using 1% starch solution as indicator.
\begin{equation} Iodine\ value=\ \frac{\left(S-B\right)\ .\ N\ .\ 12.69}{W}\nonumber \\ \end{equation}
where S is the sodium thiosulfate solution for back-titration of sample (ml), B is the sodium thiosulphate solution for back-titration of blank (ml), N is the normality of sodium thiosulfate solution, and W is the weight of the sample (g).