Introduction:
The peroxide value is a crucial measure of the quality of oils and fats. It is a method to quantify the amount of peroxide that has formed in an oil sample due to oxidation. Peroxides are unstable and can lead to rancidity, which can affect the taste and aroma of the oil. Therefore, it is important to determine the peroxide value of oils and fats to assess their freshness and shelf-life. In this article, we will discuss how to calculate peroxide value of oil.
Factors affecting peroxide value:
Several factors can affect the peroxide value of oils and fats. The most important factor is the degree of unsaturation of fatty acids. Oils and fats containing unsaturated fatty acids are more susceptible to oxidation, leading to the formation of peroxides. Other factors that can affect peroxide value include exposure to light, heat, and air, as well as the presence of catalysts such as metals.
Calculation of peroxide value:
The peroxide value of an oil sample is determined by titration with a solution of iodide ion (I-) and potassium iodide (KI). Peroxides present in the oil react with the iodide ion to form iodine, which is then titrated with a standard solution of sodium thiosulfate (Na2S2O3). The peroxide value is expressed in milliequivalents of active oxygen per kilogram of oil (meqO2/kg).
The steps involved in the calculation of peroxide value are as follows:
Weigh a sample of oil (usually 5g) into a clean, dry Erlenmeyer flask.
Add 30ml of solvent (usually acetic acid-chloroform mixture) to the flask and swirl to dissolve the oil.
Add 0.5ml of saturated potassium iodide solution to the flask and swirl to mix.
Titrate the solution immediately with a standard solution of sodium thiosulfate until the yellow color disappears.
Add a few drops of starch solution and continue titration until the blue color disappears.
Repeat the titration using a blank sample (solvent and reagents only) to determine the amount of thiosulfate required to neutralize the iodine produced in the absence of peroxides.
Calculate the peroxide value using the following formula:
Peroxide value (meqO2/kg) = (volume of thiosulfate used for sample – volume of thiosulfate used for blank) x normality of thiosulfate x 1000 / weight of sample
How is peroxide value measured?
The peroxide value of oils and fats is measured using a method called titration. The oil or fat sample is mixed with a solution of potassium iodide and acetic acid-chloroform, and then titrated with a standardized solution of sodium thiosulfate. The titration process involves adding the thiosulfate solution to the sample until the iodine that has formed from the reaction between the peroxide in the sample and potassium iodide is completely neutralized.
What is the unit of peroxide value in oil?
The peroxide value is expressed in milliequivalents of active oxygen per kilogram of oil (meqO2/kg).
How do you calculate peroxide value by titration?
The peroxide value is calculated by subtracting the volume of thiosulfate used for the blank from the volume used for the sample. This value is then multiplied by the normality of the thiosulfate solution and 1000, and divided by the weight of the oil sample. The formula is as follows: Peroxide value (meqO2/kg) = (volume of thiosulfate used for sample – volume of thiosulfate used for blank) x normality of thiosulfate x 1000 / weight of sample
What is the typical peroxide value for fresh oils?
The peroxide value for fresh oils is generally low and can vary depending on the type of oil or fat. For example, the peroxide value for fresh olive oil is typically less than 20 meqO2/kg, while the peroxide value for fresh soybean oil can be up to 10 meqO2/kg.
Peroxide value calculation formula: The formula for calculating peroxide value is: Peroxide value (meqO2/kg) = (volume of thiosulfate used for sample – volume of thiosulfate used for blank) x normality of thiosulfate x 1000 / weight of sample.
Determination of peroxide value by titration: The peroxide value of oils and fats can be determined by titration with a solution of potassium iodide and sodium thiosulfate. The method involves dissolving the oil or fat sample in a solvent and adding the potassium iodide solution to initiate the reaction with peroxides. The liberated iodine is then titrated with sodium thiosulfate solution.
Determination of peroxide value by titration pdf: There are various resources available online that provide detailed protocols and procedures for determining the peroxide value of oils and fats by titration. These resources can be in the form of scientific papers, textbooks, and technical reports, and are available in PDF format.
What is peroxide value?
The peroxide value is a measure of the amount of peroxides that have formed in an oil or fat sample due to oxidation. It is a widely used indicator of the quality and freshness of oils and fats and can help determine their shelf life and stability.
Peroxide value of palm oil: The peroxide value of palm oil can vary depending on the conditions of processing and storage. Fresh, unprocessed palm oil typically has a peroxide value of less than 10 meqO2/kg, while processed and stored palm oil can have a peroxide value of up to 20 meqO2/kg.
Peroxide value of coconut oil: The peroxide value of coconut oil can vary depending on the processing method and storage conditions. Fresh, unprocessed coconut oil typically has a peroxide value of less than 5 meqO2/kg, while processed and stored coconut oil can have a peroxide value of
What is peroxide value?
Peroxide value is a measure of the amount of peroxides that have formed in an oil or fat sample due to oxidation.
Why is peroxide value important?
Peroxide value is important because it can indicate the quality and freshness of oils and fats, and can help determine their shelf life and stability.
What is the unit of peroxide value in oil?
The peroxide value is expressed in milliequivalents of active oxygen per kilogram of oil (meqO2/kg).
How is peroxide value measured?
The peroxide value of oils and fats is measured using a method called titration. The oil or fat sample is mixed with a solution of potassium iodide and acetic acid-chloroform, and then titrated with a standardized solution of sodium thiosulfate.
How do you calculate peroxide value by titration?
The peroxide value is calculated by subtracting the volume of thiosulfate used for the blank from the volume used for the sample. This value is then multiplied by the normality of the thiosulfate solution and 1000, and divided by the weight of the oil sample. The formula is as follows: Peroxide value (meqO2/kg) = (volume of thiosulfate used for sample – volume of thiosulfate used for blank) x normality of thiosulfate x 1000 / weight of sample.
What is the typical peroxide value for fresh oils?
The peroxide value for fresh oils is generally low and can vary depending on the type of oil or fat. For example, the peroxide value for fresh olive oil is typically less than 20 meqO2/kg, while the peroxide value for fresh soybean oil can be up to 10 meqO2/kg.
How can peroxide value be reduced in oil?
Peroxide value can be reduced in oil by minimizing exposure to heat, light, and air, which can cause oxidation. Adding antioxidants to the oil can also help reduce peroxide value.
What are the sources of error in peroxide value determination by titration?
Sources of error in peroxide value determination by titration include improper sample preparation, inaccurate titrant concentration, incomplete reaction, and interference from other compounds in the sample.
How can peroxide value be controlled during oil processing?
Peroxide value can be controlled during oil processing by minimizing exposure to heat and light, adding antioxidants to the oil, and monitoring peroxide value during processing to ensure that it stays within acceptable limits.
What are the health risks associated with high peroxide value in oil?
High peroxide value in oil can indicate that the oil is rancid and may contain harmful compounds such as free radicals and aldehydes, which can increase the risk of cancer, heart disease, and other health problems. It is important to avoid consuming oils with high peroxide values.
Conclusion:
The peroxide value is an important measure of the quality of oils and fats. It is used to assess the freshness and shelf-life of oils and fats and to monitor the effectiveness of antioxidant additives. The peroxide value is calculated by titration with a solution of iodide ion and potassium iodide. The method is simple, rapid, and widely used in the food industry. By understanding how to calculate peroxide value of oil, one can ensure the quality and safety of oils and fats in their products.
