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.
|Published (Last):||21 January 2012|
|PDF File Size:||9.56 Mb|
|ePub File Size:||2.66 Mb|
|Price:||Free* [*Free Regsitration Required]|
The green potentiometric method for the determination of the acid number of oils and fats herein proposed 3c-63 similar but more accurate and precise results to 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.
No evidence for systematic differences was observed. The electrodes were calibrated as usual with aqueous buffer solutions of pH 7.
A green potentiometric method for determination of the acid number of oils and fats
The 3d63 of these acids indicates how the feedstock was treated during industrial processing and during the storage. April 4, Published online: With respect to the precision of the methods, it is clear that the green potentiometric procedure herein proposed presents the best performance. Despite the fact that the potentiometric methods can be more easily applied, in comparison to the visual method, as they do not depend on the color of the sample, in presence of organic solvents, the glass membrane of the electrode is dehydrated, a fact that results in instability of the measured electric potential.
The sample is then added and the obtained solution officjal titrated under vigorous shaking throughout until the moment a pink color that persists for dc s is observed. 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 the air. This situation not only reduces the time of the analysis, but also minimizes the possible effect of dehydration of the electrode as it remains for a shorter period in contact with the 1: Distilled water was obtained from a glass distiller.
Therefore, the present work has as objective to apply potentiometric detection to the titrimetric method aiming at odficial cost, operational simplicity and, especially, as environmentally friendly procedure. Recently a green visual titrimetric method was presented for the determination officcial the acid number of oils and fats, using as titrant an aqueous 0.
High concentrations mean loss of money as the rating of the product decreases.
aocs official method cd 3d-63 pdf
C is the concentration of the titrant solution mol L -1and m is the mass of the sample g. Rapid preventive rehydration 1 min is enough to maintain the membrane of the xd in good conditions.
Offcial Cd 3d official method 28 The acid number of oils and fats is determined through the titration of the sample with a standardized 0. In order to verify the accuracy of the potentiometric procedure developed with respect to the AOCS Cd 3d and to the two other applied methods, a statistical weighted linear regression procedure was used. The acid number is a parameter that quantifies the acid products of degradation reactions of an oil or a fat.
The acid number of oils and fats is determined through the titration of the sample with a standardized 0. Conclusion 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 to those obtained by the AOCS Cd 3d and by the ABNT-NBR methods that use organic solvents, such as toluene, cf as titrant a KOH solution in isopropyl alcohol.
Reagents, solutions and solvents. The other methods present similar standard deviation among them with a little lower value for RSD for green visual procedure. This solvent mixture is previously neutralized with the standard KOH solution using phenolphthalein until the appearance of a slight pink color. The solutions of the bases were stored in alkaline resistant bottles.
These reactions cause the breaking of the triacylglycerol molecule leading to the formation of free fatty acids which are responsible for the unpleasant flavor characteristic of the oxidized fats as for example, rancid butter.
According to this method, a quantity of the sample, which varies with its acidity, is dissolved in mL of a solvent that is a 1: A Metrohm Solvotrode, 3.
Soy, corn, canola, sunflower, linseed and castor oils and swine lard used in the present study were purchased at local markets. The acid number is calculated using equation officual. 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. The sample is dissolved in a water-ethanol mixture 1: How to cite this article.
Because of the above observations, it is evident that the precision of the proposed green potentiometric oacs is higher than of the all others here used for comparison. Analytical procedures Green potentiometric method Weight with at least 0. In the green acs proposed in this article, the solvent is a 1: Therefore, the determination of their concentrations throughout the refining process and during the storage is important for monitoring the occurrence of degradation reactions.
Considering the above observations, the green method developed in this work can be proposed for the routine determination of the acid number of oils and fats.
The acid number of the 75 mL of solvent blank value must be obtained by a similar titration.