Why is alcohol used in acid value titration?
It is, therefore, possible to titrate the solution of the oil in the Isopropyl Alcohol without the violent shaking that is necessary in the case of the Spe- cially Denatured Alcohol. This is a marked advantage, for in oils of high free fatty acid content there is possibility of error if the shaking is insufficient.
Why must the alcohol used as solvent for oil in acid value determination be neutral?
The neutral solvents helps you find the exact acidity from free fatty acids present in a fat sample.. if your solvent is not neutral it may consume more sodium hydroxide (if it acidic) and less if solution is basic,leading to wrong estimation of fee fatty acid analysis.
Why methanol or ethanol is used in acid value determination for oils?
AVs were determined by the AOCS Method Te 2a-64 (Firestone, 1994) with ethanol substituted for methanol to increase the solubility of the estolide ester during the titration. … The AV for the estolide esters shows the amount of mg g−1 of KOH between the ester and free-acid estolides.
Why do we neutralize ethanol?
Ethanol for analytic purposes is said to be neutralized when potassium or sodium hydroxide is added to ethanol containing a pH indicator, such phenolphthalein, until its color begins to turn. The solution can then be used in a titration to determine the pH of a test solution.
What is the pH of ethanol?
The pH of 100% ethanol is 7.33, compared to 7.00 for pure water.
What is the difference between acid value and saponification value?
The key difference between acid value and saponification value is that acid value gives the mass of potassium hydroxide that is required to neutralize one gram of a chemical substance whereas saponification value gives the mass of potassium hydroxide required to saponify one gram of fat.
Why is phenolphthalein used as an indicator in saponification value of fats?
Explanation: Phenolphthalein is chosen because it changes color in a pH range between 8.3 – 10. It will appear pink in basic solutions and clear in acidic solutions.
Why saponification value is determined?
It is a measure of the average molecular weight (or chain length) of all the fatty acids present in the sample as triglycerides. The higher the saponification value, the lower the fatty acids average length, the lighter the mean molecular weight of triglycerides and vice-versa.
Is cooking oil acid base or neutral?
Because only aqueous solutions have pH levels, vegetable oil has no pH value. Likewise, other oils such as animal and petrochemical oils also have no pH value.
What does the acid value indicate?
The acid value is defined as the number of milligrams of Potassium hydroxide required to neutralize the free fatty acids present in one gram of fat. It is a relative measure of rancidity as free fatty acids are normally formed during decomposition of triglycerides.
What is significance of determining the acid value of an oil?
The acid value (AV) in edible oils, defined as the amount of potassium hydroxide (KOH, in milligrams) necessary to neutralize the free fatty acids contained in 1 g of oil,1,2 is one of the important parameters related to the oil quality. A high AV indicates the deterioration of oil, which affects its nutritive value.
Which type of indicator is used in acid value determination?
In a typical procedure, a known amount of sample dissolved in an organic solvent (often isopropanol) and titrated with a solution of potassium hydroxide (KOH) of known concentration using phenolphthalein as a colour indicator.
What is the color of ethanol?
Ethanol appears as a clear colorless liquid with a characteristic vinous odor and pungent taste.
Why does oil increase in FFA?
Free fatty acids form during frying due to the presence of moisture in the foods exposed to oil. Normally, 0.5–0.8% FFA is encountered. If the frying rate is insufficient to drive water from food at a sufficient rate, the FFA content increases rapidly. High-FFA frying oil smokes at a progressively lower temperature.
How do you make neutral ethanol?
Neutral ethanol is distilled via column distillation because it strips out more of the impurities and congeners. For beverages, the “heart” is the most desirable part of the liquid. This is where you get the flavour without the bitterness of the heads. That said, heads and tails are still of use.