The determination is carried out by dissolving a weighed sample in a nonpolar solvent such as cyclohexane, then adding glacial acetic acid. This method also uses pyridinium tribromide as a bromine source. The result is expressed as g of iodine i2 per 100 g of sample. Estimation of iodine value of fats and oils procedure. Pdf determination of iodine value in triisocetyl citrate citmol.
Introduction the iodine value of animal and vegetable fats and oils measures the amount of cc double bonds present in the product. The present work describes a novel procedure for determination of iodine value based. The most important application of the iodine value is to determine the amount of unsaturation contained in fatty acids. The method was used for determination of iodine value of 12 edible vegetable oils as well as castor and linseed oils. Iodine value means the g value of halogen which adhere to g of methods such as hanus method and wijs method for iodine value. The iodine value or iodine adsorption value or iodine number or iodine index in chemistry is the mass of iodine in grams that is consumed by 100 grams of a chemical substance. Twentytwo laboratories participated in a collaborative test to determine the iodine value iv of eight samples of fish oil four with iv 150 with either carbon tetrachloride aocs official method cd 125 or cyclohexane aocs recommended practice cd 1b87 as solvent and either 1 or 2 h of reaction time. Scope applicable to all normal fats and oils with iodine values in the range of 18165 that do not. The iodine value can be determined for fats and oils with thermometric titration, by dissolving a weighed sample in a nonpolar solvent and then adding glacial acetic acid. The mean value of the blank determination method 051b is automatically stored as auxiliary value h3. Results for this 1990 study were submitted by 18 laboratories from 11 countries.
Iodine value is an important quality parameter for evaluation of the oxidative stability of. An experiment has been developed that combines the ftir analysis of oils and fats with an iodometric titration. Triglycerides are made up of three fatty acids linked to glycerol by fatty acyl esters. Simple spectrophotometric method for determination of. Fatty acids react with a halogen iodine resulting in the addition of the halogen at the cc double bond site. Cautions in measurement 1 reagent and additives must be handled in a well ventilated room or in a draft. D1959 test method for iodine value of drying oils and fatty acids.
Iodine value, also called iodine number, in analytical chemistry, measure of the degree of unsaturation of an oil, fat, or wax. Petroleum iodine value of oil and fat kyoto electronics. Determination of iodine value iv in fats and oils using. The iodine value is a measure of the degree of unsaturation in an oil. The total iodine value also includes the iodide ions which are necessary for formation of the complex. The higher the iodine number is, the more unsaturated the fat. Annex a describes a method for the calculation of the iv from fatty acid compositional data. The iodine value is a measure of the unsaturation 3.
Determination of iodine value of oil lipids laboratory. E691 practice for conducting an interlaboratory study to determine the precision of. Fatty acid composition of vegetable oils as determined by gas liquid. To calculate the iodine number using the method described, below, all one need do is obtain the volume of na 2. As a general rule, if the iodine number is in the range of 070, then youre looking at a fat. It is expressed as the number of milligrams of potassium hydroxide koh required to saponify 1 gram of the test sample. Laboratories received coded duplicate samples hidden duplicates. The method is suitable for edible fats and oils such as butter, olive, palm or sunflower oil.
The calculation of the % ffa depends on the titrated type of sample. Determination of the iodine value of selected oils. Collaborative test of determination of iodine value in. Pdf standard test method for determination of the iodine. A laboratory exercise was devised that allows students to rapidly and fairly accurately determine the iodine value of oleic acid. Determination of physicochemical constants of fats and. Determination of iodine value and acid value of red fruit. The iodine value is a measure of the unsaturation of fats and oils and is expressed in terms of the number of centigrams of iodine absorbed per gram of test sample % iodine absorbed. If we use for the determination of the iodine value the method described in our previous work then all these constants can be determined practically on the basis of. It is expressed as the iodine in grams that will react with the double bonds in 100 grams of fats or oils. This method utilizes the addition of elemental bromine to the unsaturated bonds in oleic acid, due to bromines relatively fast reaction rate compared to that of the traditional wijs solution method. This unsaturation is in the form of double bonds, which react with iodine compounds. Iv is a measure of the number of double bonds in the unsaturated fatty acids in one gram of oil. Determination of iodine value of fats and oil discover.
About 5 g of accurately weighed povidoneiodine is placed in a 400ml beaker, and 200 ml of distilled water is added. In linoleic acid and cod liver oil the hanus method gives 2 to 4 per cent higher values than the other. Estimation of iodine value of fats and oils theory. The ester determination is dominated by the following numbers. The saponification value is the amount of alkali necessary to saponify a definite quantity of the test sample. Iodine numbers are often used to determine the amount of unsaturation in fatty acids. The iodine value in chemistry is the mass of iodine in grams that is consumed by 100 grams of a chemical substance. The official methods for determination of iodine value 3 involve the reaction of sample with halogenating reagent, hanus or wijs solution follows by iodometrically determine the unreacted reagent. The processors of oil and fat are in need of a quick determination method of iodine value of oils and fats especially in case of checking the degree of. Authors have investigated other methods of quick determination of iodine value especially for the oils in the hydrogenation process and have found after all the wijs method could be appropriate by only shortening the reaction time to three minutes for the oils of the iodine value less than about 100. The iodine value can be determined for fats and oils with thermometric titration, by dissolving a weighed sample in a nonpolar solvent and then. Astmd5554 standard test method for determination of the. A higher iodine value indicates a higher degree of unsaturation.
Aocs official method cd 1d92 american oil chemists society. Iodine value of sunflower oil the determination of iodine value is of great importance in finding the proportion of adulteration in oils this gives an idea of its drying character. Iodine value of fats and oils wijs cyclohexaneacetic acid solvent method first action 1993 final action 1996 iupacaocsaoac method applicable to determination of iodine value for fats and oils which do not contain conjugated double bonds. Iodine value is a useful parameter in studying oxidative rancidity of oils since higher the unsaturation the greater the possibility of. Oils with iv ranging from 10 to 190 were tested and found to give satisfactory. A modified determination of iodine value in fats, fatty acids, and fatty acid derivatives is reported. Iodine value or number is the number of grams of iodine consumed by 100g of fat. To determine the iodine value of fats and oils and thus estimate the unsaturation of the fat oil. China, czechoslovakia, the federal republic of germany 3 finland 2 hungary, japan 2, malayasia, netherlands, new zealand 2, south africa, the united kingdom 2, and the united states. Mean while, take out the test from incubation after 30 minutes and add 10 ml of potassium iodide solution into the flask. Iodine value iv is a measure of the total number of double bonds present in fats and oils.
The higher iodine value indicates the greater the degree of unsaturation. The iodine number is a degree for the content of unsaturated fatty acids. E177 practice for use of the terms precision and bias in astm test methods. Obtaining the iodine value of various oils via bromination. Add to the blank, 20ml of iodine monochloride reagent and mix the contents in the flask thoroughly. It is defined as the weight of koh in mg needed to neutralize the organic acids present in 1g of fat and it is a measure of the free fatty acids ffa in a sample of oil or fat indicates hydrolysis of triglycerides. The iodine value can be determined for fats and oils with.
Annex b describes a method for the calculation of the iv from fatty acid compositional data. Iodine number determination using 110 017 ftir atr. Pdf determination of iodine value of palm based on triglyceride. Iodine value is a useful parameter in studying oxidative rancidity of oils since higher the unsaturation the greater the possibility of the oils to go rancid. Determination of the iodine value of oils and fats results. Determination of the iodine value and the free fatty acid. Find upgrades, patches, documents, and language versions for your software. The iodine number is by definition the amount of iodine in gram necessary to bound 100 g fat under decoloring. Pdf a b s t r a c t the iodine value iv also called iodine number or iodine.
On the other hand, linseed oil is highly unsaturated, which makes it a drying oil. Integration of the experiment into an upperlevel biochemistry laboratory is described. The iodine value is expressed in grams of iodine for the amount of halogens linked with 100g test sample, and is used as degree of unsaturated bond of fats and oils. Determination of physicochemical constants of fats and oils from the. Iodine value of edible oils and fats according to wijs. In their study, it was reported that over 1200 samples of processed, blended oil samples and some animal fats milkfat, beef tallow, fish and lard were used for the calibration and validation of the plsnir iv model developed. This international standard specifies a reference method for the determination of the iodine value commonly known in the industry as iv of animal and vegetable fats and oils, hereinafter referred to as fats. It is expressed as the number of grams of iodine that will react with the double bonds in. This method provides an assay value for a sample of povidoneiodine.
The laboratory experiments on lipids earlier included the iodine absorption test, to compare semiquantitatively the degree of unsaturation in fatty acids present in common edible oils. This video looks at both the practical procedure and the calculation, for obtaining the iodine values of fats and oils. Determination of iodine value iv in fats and oils with thermometric. The iodine value is a measure of the unsaturation of fats and oils and is expressed in terms of the number of centigrams of iodine absorbed per gram of sample. Fast spectrophotometric determination of iodine value in biodiesel. For the determination of the iodine number of oleic and ricin oleic acids both the hanus and the rosenmund methods give the same value which is very near the theoretical. It is expressed as the number of grams of iodine that will react with the double bonds in 100 grams of fats or oils. The acid number is the quantity of base, expressed in milligrams of potassium hydroxide, that is required to. Iodine value is used to compare the number of cc contained in natural complex mixture. The analytical methodology of its evaluation includes the use of.
Iodine value iv is a measure of the total number of double bonds. Standard test method for determination of the iodine value. Moisture content of oils and fats is the loss in mass of the sample on heating. Determination of iodine value iv in fats and oils with. This document specifies a reference method for the determination of the iodine value commonly known in the industry as iv of animal and vegetable fats and oils, hereinafter referred to as fats. Acid value determination in vegetable oils 101 croat. Standard test method for determination of iodine value of. D1541 test method for total iodine value of drying oils and their derivatives. Determination of iodine value in palm oil cdr foodlab. The iodine number equals the number of mg of iodine required. Introduction the acid value av is a common parameter in the specification of fats and oils. The described procedures, visual and potentiometric, have wide applicability and generate. Iodine value iv is a measure of the unsaturation of fats and. Calculation of iodine value from measurements of fatty acid methyl.
While it is most appropriate for a sophomore or junior laboratory for majors, it also makes a suitable group project or demonstration for nonscience majors. Saponification value or saponification number, also referred to as sap in short, represents the number of milligrams of potassium hydroxide or sodium hydroxide required to saponify 1g of fat under the conditions specified. Test method for measurement of iodine value of fats and oils stipulated in the below quoted standards is. The larger the iodine value the greater the degree of unsaturation. Physicochemical constants such as the iodine value, the saponification value, the refractive index, the combustion heat, the specific gravity, the neutralization value, the iodinesaponification factor, and the hardness. Determination of saponification and iodine value of. It is expressed as the number of grams of iodine that will react with the double bonds in 100 grams of fats or oils the determination is conducted by dissolving a weighed sample in a nonpolar solvent such as cyclohexane, then adding glacial acetic acid. Iodine value test with cdr palmoiltester palm oil analysis system. Acid value determination in vegetable oils by indirect. Animal and vegetable fats and oils determination of iodine value.
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