I have been performing peroxide value test for oil samples according to AOCS method but after adding starch solution to the sample it does not turn blue in colour.
I have taken 1g oil sample, added 3ml of acetic acid:chloroform(3:2), 100uL of Potassium iodide and 3 ml water. Adding starch does not cause colour change. I have tried adding 6 ml of Acetic Acid and chloroform solution but that did not help either.
Any form of help or suggestion would be appreciated.
Dear friend Satish Bhande
The absence of blue color after adding starch solution to the peroxide value test mixture may indicate a low concentration of peroxides in the oil sample or a problem with the starch solution itself. It is recommended to check the freshness and concentration of the starch solution, as well as the accuracy of the peroxide value test protocol.
Additionally, it is important to note that the peroxide value test may not be suitable for all types of oils and fats, and alternative methods such as the thiobarbituric acid reactive substances (TBARS) assay may be more appropriate in certain cases.
References:
1. AOCS Official Method Cd 8b-90. Peroxide Value Acetic Acid-Chloroform Method.
2. Damodaran, S., Parkin, K. L., & Fennema, O. R. (2010). Fennema's food chemistry. CRC press.
The peroxide value test is a common method used to measure the amount of peroxides in a sample of oil or fat, which can indicate the level of oxidation or rancidity. The blue color formation that occurs after the addition of starch solution to the test sample is due to the reaction between the remaining iodine and the starch.
If the starch solution does not turn blue in your peroxide value test, it could be due to various reasons such as:
Thank you Kaushik Shandilya . I found out that the issue was with my starch solution. I think it is important to add the starch in water and then bring it to a proper boil prior to filtering it through filter paper. A blank test helps in identifying whether the prepared starch solution is working properly.
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