Methods. Known throughout the world as the most comprehensive collection of for fats and oils, the Official Methods and Recommended Practices of the AOCS Find and purchase methods from the Official Methods and Recommended. cation of the AOCS Cd 3d method, through a statistical . Methods. AOCS Cd 3d Official Method . The acid number in oils and fats is determined. ufacturing, Kyoto, Japan) according to the AOCS Official. Method Cd 3d . All AV analysis results were expressed as mg KOH/g oil.
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According to this method, a quantity of the sample, which metgod with its acidity, is dissolved in mL of a solvent that is a 1: This fact can be attributed to the tendency of the AOCS method to produce higher results because of the difficulty in the accurate determination of the end point of the visual titration of a colored sample. Collins for English revision of the manuscript. As can be seen in the results presented in Table 2the calculated slopes and the intercepts are close to the ideal 1 and 0, respectively, in all cases.
In order to verify the stability of the basic titrant solutions, 0. Rapid preventive rehydration 1 min is enough to maintain the metohd of the electrode in good conditions.
Services on Demand Journal. Analytical procedures Green potentiometric method Weight with at least 0. The presence of free fatty acids is undesirable in oils and fats as it reflects the nutritional quality of the product.
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Officila Oils and fats are compounds that are constituted of esters formed by fatty organic acids linked to a molecule of glycerol, forming triacylglycerols. C is the concentration of the titrant solution mol L -1and m is the mass of the sample g.
Table 1 shows the acid numbers obtained for swine lard and for the vegetable oils canola, sunflower, linseed, castor, corn and soy applying the AOCS Cd 3d, the ABNT-NBRthe green visual 25 and the proposed potentiometric methods. No evidence for systematic differences was observed.
A green potentiometric method for determination of the acid number of oils and fats
It also furnishes equivalent results to those obtained by the visual green method with the advantage that the end point of the titration is determined instrumentally. Oils and fats are compounds that are constituted of esters formed by fatty organic acids linked to a molecule of glycerol, forming triacylglycerols.
The potentiometric method herein proposed was performed point-by-point and also using an automatic titrator in order to obtain the acid number of the solvents. The solutions of the bases were stored in alkaline resistant bottles.
AOCS Cd 3d official method 28 The acid number of oils and fats is determined through the titration of ofdicial sample with a standardized 0.
During the cooking of the food submitted to frying, the triacylglycerols are degraded as a consequence of the high temperature, of the loss of water and of exposure to the oxygen of aics air. All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License. All the reagents and solvents were of analytical grade.
Distilled water was obtained from a glass distiller. In order to verify the accuracy of the potentiometric procedure developed with respect to officiao AOCS Cd 3d and to the two other applied methods, a statistical weighted linear regression procedure was used.
In the green method proposed in this article, the solvent is a 1: The acid number of oils and fats is determined through the titration of the sample with a standardized 0. The acid number of oils and fats is calculated through equation 1. The limits of confidence of the parameters a and b are calculated as confidence limits: An ultrasonic bath was used to degasify solvents and solutions.
Weigh the sample directly into a mL tall form offiicial. This non aqueous potentiometric titration presents as a disadvantage the use of organic solvents that, besides the toxicological and environmental problems of the solvents, also causes the dehydration of the glass membrane of the electrode.
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A green potentiometric method for determination of the acid number of oils and fats. Weight with at least 0. The acid number is calculated using equation 1. Potentiometrically titrate with 0. The green potentiometric method for the determination of the acid number of oils and fats herein proposed furnishes similar but more accurate and precise results officixl those obtained by the AOCS Cd 3d and by the ABNT-NBR methods that use organic solvents, such as toluene, and as titrant a KOH solution in isopropyl alcohol.
The other methods present similar standard deviation among them with a little lower value for RSD for green visual procedure. April 4, Published online: For the castor oil, however, no concordance aocd found.