Mustard Oil Analysis

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I. Mustard Oil
II. Potato
Mustard Oil was procured from the local market of Hansi. Potato is also procured from Hansi market. All chemicals used in this study were of analytical grade.
Effect of repeated frying on quality of edible oil (mustard) was evaluated by estimating the free fatty acid content, peroxide value, viscosity and color analysis.1-liter oil was taken in open pan for heating followed by frying of products (potato slice: 40 gm). There were four types of samples: S1 (only oil), S2 (oil + potato slice), S3 (oil + potato slice + 50 PPM BHT) and S4 (oil + potato slice + 75 PPM BHT). Out of these four samples, frying was carried out only in three cases while one sample
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Total colour difference was calculated using the equation:
TCD= ½{(Lo-L) ²+ (Ao-A) ²+ (Bo-B) ²}
Where, TCD represents the total color change; Lo, Ao and Bo refers to reference values, i.e., colour parameters of fresh oil, and L, A and B refer to colour values after storage of frying mustard oil (Pathare et al., 2012).
Yellowness Index =142.86b*/L* Refractive Index: - It was determined by the help of hand refractometer, which works on the principle of total refraction. A drop of the sample was placed on the plate to read the refractive index in oBrix. Refractive index is the ratio of velocity of light in vacuum to the velocity of light in the oil or fat; more generally, expresses the ratio between the sine of angle of incidence to the sine of angle of refraction when a ray of light of known wave length (usually 589.3 nm, the mean of D lines of Sodium) passes from air into the oil or fat.

3.2.3 Chemical
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The sample is dissolved in solvent , treated with potassium iodide, and the iodine liberated by the peroxides present in rancid fat or oil is treated with sodium thiosulphate solution often the number of millimoles of peroxide oxygen is reported , and the result is then half that of peroxide value. In case , the term “lea-value” is frequently used.


1. Solvent: Mix 2 volumes of glacial acetic acid and 1 volume of chloroform.
2. Saturated potassium iodide solution: Dissolve4 parts of pure potassium iodide in 3 parts of distilled water. keep the solution in a brown bottle.
3. 0.1 N Sodium thiosulphate solution
4. 0.5 % starch indicator

1. Take an aliquot of the extracted fat of the sample in to a conical flask.
2. Then add 25 ml of the solvent and displace the air above the liquid with Co2.
3. Then add 1 ml of the potassium iodide solution, stopper the flask and allow it to stand for 1 min.(with shaking).
4. Now add 35 ml of water and titrate using starch as indicator.
5. Carry out a blank determination simultaneously.


Peroxide value
Per 1,000 g of fat = {sample titer – Blank titer} x N of Na2S2O3. X 1000/wt of

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