ISO/TC 34/SC 11 - Animal and vegetable fats and oils

This document specifies a rapid procedure for the simultaneous determination of 2-MCPD esters (bound 2-MCPD), 3‐MCPD esters (bound 3‐MCPD) and glycidyl esters (bound glycidol) in a single assay, based on alkaline catalysed ester cleavage and derivatization of cleaved (free) analytes with phenylboronic acid (PBA) prior to GC-MS/MS analysis. Glycidyl ester overestimation is corrected by addition of an isotopic labelled ester bound 3-MCPD which allows the quantification of 3-MCPD induced glycidol during the procedure. This method is applicable to solid and liquid fats and oils. This document also applies to animal fats and used frying oils and fats, but these matrices were not included in the validation. For all three analytes the limit of quantification (LOQ) is 0,1 mg/kg and the limit of detection (LOD) is 0,03 mg/kg. Milk and milk products (or fat coming from milk and milk products), infant formulas, emulsifiers, free fatty acids and other fats- and oils-derived matrices are excluded from the scope of this document.

This document specifies a method for the semi-quantitative analysis of oils, fats and oil/fat-related samples (deodistillates). It is applicable to the screening of oils, fats and oil/fat-related samples to obtain main (e.g. triglycerides) and minor (e.g. sterols, sterol esters, tocopherols, wax esters, fatty alcohols, glycerol) component information in one single analysis. For a truly quantitative analysis of pre-identified compound classes, specific methods are more appropriate. The method can also be used as a useful qualitative screening tool for the relative comparison of sample compositions.

This document specifies two methods for the determination of the melting point in open capillary tubes, commonly known as the slip melting point, of animal and vegetable fats and oils (referred to as fats hereinafter). — Method A is only applicable to animal and vegetable fats which are solid at ambient temperature and which do not exhibit pronounced polymorphism. — Method B is applicable to all animal and vegetable fats which are solid at ambient temperature and is the method to be used for fats whose polymorphic behaviour is unknown. For the determination of the slip melting point of palm oil samples the method given in Annex A shall be used. NOTE 1 If applied to fats with pronounced polymorphism, method A will give different and less satisfactory results than method B. NOTE 2 Fats which exhibit pronounced polymorphism are principally cocoa butter and fats containing appreciable quantities of 2-unsaturated, 1,3-saturated triacylglycerols.

This document specifies a method for the quantitative determination of hydroxytyrosol and tyrosol content in extra virgin olive oils using reverse phase high performance liquid chromatography (RP-HPLC) with spectrophotometric detection. The method is also applicable to all other olive oils of a different commercial category.

This document specifies a method for the determination of the saponification value of animal and vegetable fats and oils. The saponification value is a measure of the free and esterified acids present in fats and fatty acids. The method is applicable to refined and crude vegetable and animal fats. If mineral acids are present, the results given by this method are not interpretable unless the mineral acids are determined separately. The saponification value can also be calculated from fatty acid data obtained by gas chromatography analysis as given in Annex B. For this calculation, it is necessary to be sure that the sample does not contain major impurities or is thermally degraded.

This document specifies three methods (two titrimetric and one potentiometric) for the determination of acidity in animal and vegetable fats and oils, hereinafter referred to as "fats". The acidity is expressed preferably as acid value or, alternatively, as acidity calculated conventionally. This document is applicable to refined and crude vegetable or animal fats and oils, soap stock fatty acids or technical fatty acids. It does not apply to waxes. Since the methods are completely non-specific, they do not apply to differentiating between mineral acids, free fatty acids and other organic acids. The acid value, therefore, includes any mineral acids that are present. Milk and milk products (or fat coming from milk and milk products) are excluded from the Scope of this document.

This document specifies a reference method for the determination of free sterols/stanols and steryl/stanol esters (0,1 % to 97 % mass fraction) in foods and dietary supplements containing added phytosterols and in phytosterol food additive concentrates. Milk and milk products (or fat coming from milk and milk products) are excluded from the scope of this document. This method does not apply to matrices that contain rice bran oil at concentrations of more than 20 % due to possible interferences in the gas chromatogram.

This document specifies a procedure for the determination of the content, as a mass fraction expressed as milligrams per kilogram, of aliphatic and triterpenic alcohols in olive oils and olive-pomace oils. NOTE This document is based on COI/T.20/Doc. 26 Rev.2:2017[4].

This document specifies a method for the determination of the content of toluene insoluble matter (TIM) in lecithin formulations, which indicates the presence of impurities such as protein, carbohydrate-containing extraction residues and other solid contaminants. This method is applicable to all types of vegetable lecithin. The purpose of the method is to enable the analysis of lecithin under several regulations. Lecithin [Codex International Numbering System for Food Additives (INS) No. 322] is a generally permitted additive and the determination of the TIM is part of many specifications. The purity requirement with regard to TIM content is based on the method specified. Toluene is the replacement for the carcinogenic benzene, which was used in older methods.

This document specifies a procedure for the parallel determination of glycidol together with 2-MCPD and 3-MCPD present in bound or free form in oils and fats. The method is based on alkaline-catalysed ester cleavage, transformation of the released glycidol into monobromopropanediol (MBPD) and derivatisation of the derived free diols (MCPD and MBPD) with phenylboronic acid (PBA). Though free MCPD and glycidol are supposed to be present in fats and oils in low to negligible quantities only, in the event that free analytes are present, they would contribute proportionately to the results. The results always being the sum of the free and the bound form of a single analyte. This method is applicable to solid and liquid fats and oils. This document can also apply to animal fats and used frying oils and fats, but a validation study is undertaken before the analysis of these matrices. Milk and milk products (or fat coming from milk and milk products) are excluded from the scope of this document.

This document specifies the determination of composition of triacylglycerols and the determination of the composition and content of diacylglycerols by capillary gas chromatography in vegetable oils with a lauric acid content below 1 %. Applying certain technological processing 1,2-diacylglycerols (1,2-DAGs) are transformed to the more stable isomeric 1,3-diacylglycerols (1,3-DAGs) due to acidic catalysed reaction. During storage, the speed and amount of this rearrangement depends on the acidity of the oil. The transformation normally reaches an equilibrium between the two isomeric forms. The relative amount of 1,2-DAGs is related to oil freshness or to a possible technological treatment. Therefore, it is possible to use the ratio of 1,2-DAGs to 1,3-DAGs as a quality criterion for vegetable fats and oils. The triacylglycerols profile is of potential interest for the fingerprint of each vegetable oil and may help the detection of certain types of adulteration, such as the addition of high oleic sunflower oil or palm olein in olive oil. NOTE This document is based on Reference [3].

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. Annex B describes a method for the calculation of the IV from fatty acid compositional data. This method is not applicable to fish oils. Furthermore, cold-pressed, crude and unrefined vegetable oils as well as (partially) hydrogenated oils can give different results by the two methods. The calculated IV is affected by impurities and thermal degradation products. NOTE The method in Annex B is based upon the AOCS Official method Cd 1c-85[10].

ISO 18363-3:2017 specifies a procedure for the simultaneous determination of 2-MCPD esters (bound 2-MCPD), 3‐MCPD esters (bound 3‐MCPD) and glycidyl esters (bound glycidol) in a single assay, based on acid catalysed ester cleavage and derivatization of cleaved (free) analytes with phenylboronic acid (PBA) prior to GC/MS analysis. ISO 18363-3:2017 is applicable to solid and liquid fats and oils. For all three analytes the limit of quantification (LOQ) is 0,1 mg/kg and the limit of detection (LOD) is 0,03 mg/kg.

ISO 12966-2:2017 specifies methods of preparing the methyl esters of fatty acids. It includes methods for preparing fatty acid methyl esters from animal and vegetable fats and oils, fatty acids and soaps. To cover different requirements, four methylation methods are specified, namely: a) a "rapid" transmethylation procedure under alkaline conditions; b) a "general" transmethylation/methylation procedure under sequential alkaline and acid conditions; c) a BF3 transmethylation procedure; d) an alternative procedure using acid-catalysed transmethylation of glycerides. Methyl esters so produced are used in various analytical procedures requiring such derivatives, e.g. gas-liquid chromatography (GLC), thin-layer chromatography (TLC) and infrared spectrometry (IR). Milk and milk products (or fat coming from milk and milk products) are excluded from the scope of this document.

ISO 15302:2017 specifies a method for the determination of benzo[a]pyrene in crude or refined edible oils and fats by reverse-phase high performance liquid chromatography (HPLC) using fluorimetric detection in the range 0,1 µg/kg to 50 µg/kg. Milk and milk products (or fat coming from milk and milk products) are excluded from the scope of this document.

ISO 6320:2017 specifies a method for the determination of the refractive index of animal and vegetable fats and oils. Milk and milk products (or fat coming from milk and milk products) are excluded from the scope of this document.

ISO 15774:2017 describes a method for the determination of trace amounts (micrograms per kilogram) of cadmium in all types of crude or refined edible oils and fats. Milk and milk products (or fat coming from milk and milk products) are excluded from the scope of this document.

ISO 8534:2017 specifies a method for the determination of the water content of animal and vegetable fats and oils (hereinafter referred to as fats) using Karl Fischer apparatus and a reagent which is free of pyridine. Milk and milk products (or fat coming from milk and milk products) are excluded from the scope of this document.

ISO 663:2017 specifies a method for the determination of the insoluble impurities content of animal and vegetable fats and oils. If it is not desired to include soaps (particularly calcium soaps) or oxidized fatty acids in the insoluble impurities content, it is necessary to use a different solvent and procedure. In this case, an agreement is to be reached between the parties concerned. Milk and milk products (or fat coming from milk and milk products) are excluded from the scope of this document.

ISO 6883:2017 specifies a method for the determination of the conventional mass per volume ("litre weight in air") of animal and vegetable fats and oils (hereinafter referred to as fats) in order to convert volume to mass or mass to volume. The procedure is applicable to fats only when they are in a liquid state. Milk and milk products (or fat coming from milk and milk products) are excluded from the scope of this document. NOTE The determination of conventional mass per volume (litre weight in air) using the oscillating U-tube method can be found in ISO 18301.

ISO 3960:2017 specifies a method for the iodometric determination of the peroxide value of animal and vegetable fats and oils with a visual endpoint detection. The peroxide value is a measure of the amount of oxygen chemically bound to an oil or fat as peroxides, particularly hydroperoxides. The method is applicable to all animal and vegetable fats and oils, fatty acids and their mixtures with peroxide values from 0 meq to 30 meq (milliequivalents) of active oxygen per kilogram. It is also applicable to margarines and fat spreads with varying water content. The method is not suitable for milk fats and is not applicable to lecithins. It is to be noted that the peroxide value is a dynamic parameter, whose value is dependent upon the history of the sample. Furthermore, the determination of the peroxide value is a highly empirical procedure and the value obtained depends on the sample mass. It is stressed that, due to the prescribed sample mass, the peroxide values obtained can be slightly lower than those obtained with a lower sample mass. Milk and milk products (or fat coming from milk and milk products) are excluded from the scope of this document. NOTE 1 A preferred method for the iodometric determination of the peroxide value for milk fats is specified in ISO 3976. NOTE 2 A method for the potentiometric determination of the peroxide value is given in ISO 27107.

ISO 11702:2016 specifies a method for the quantitative determination of the total sterols content by means of an enzymatic staining test. The method is applicable to free and esterified sterols in animal and vegetable fats and oils, fatty foods and related products. The determination is applicable to sample quantities of 1 g to 2 g of fat. The method is not applicable to dark coloured fats and oils. The enzyme is not specific for cholesterol, but also oxidizes other 3-hydroxysterols. The method has not been tested for products fortified with sterols at higher levels. Milk and milk products (or fat coming from milk and milk products) are excluded from the scope of ISO 11702:2016.

ISO 21033:2016 specifies an inductively coupled plasma optical emission spectroscopic method (ICP-OES) for the determination of the trace element content in oils. Depending on the dilution solvent used, most types of vegetable oils can be analysed (crude, degummed, refined, bleached, deodorized and hardened oils) and nearly all types of lecithins and phosphatides. Milk and milk products (or fat coming from milk and milk products) are excluded from the scope of this International Standard. This method is only suitable when the elements are present in a solubilized form. Fine particles, such as bleaching earth, metal particles and rust, can result in poor recovery of the trace elements present as nebulization and atomization problems affect the ICP-OES analysis. NOTE The only suitable non-ashing direct method for samples containing fine particles is graphite furnace atomic absorption spectrometry.

ISO 12966-3:2016 specifies a rapid base-catalysed transesterification method for fats and oils with trimethylsulfonium hydroxide (TMSH) to prepare fatty acid methyl esters. The method is exclusively applicable to the preparation of methyl esters of fats and oils for gas liquid chromatographic (GLC) analysis. It is applicable to all fats and oils, but excluding those coming from milk and milk products. Isomerization of unsaturated fatty acids only occurs to a minor extent and isomerized fatty acids are only present at the determination limit. As isomerization takes place, the procedure is not recommended for conjugated linoleic acid (CLA). Only about 70 % to 80 % of the free fatty acids are esterified. In the case of conjugated cyclopropyl and cyclopropenyl fatty acids, side reactions may occur, but these do not interfere with the determination of the fatty acids.

ISO 662:2016 specifies two methods for the determination, by drying, of the moisture and volatile matter content of animal or vegetable fats and oils: - method A, using a sand bath or hotplate; - method B, using a drying oven. Method A is applicable to all fats and oils. Method B is applicable only to non-drying fats and oils with an acid value less than 4. Under no circumstances are lauric oils be analysed by this method. Milk and milk products (or fat obtained from milk and milk products) are excluded from the Scope of this International Standard.

ISO 15753:2016 describes two methods for the determination of 15 polycyclic aromatic hydrocarbons (PAHs) in animal and vegetable fats and oils: - a general method; - a specific method for coconut oil and vegetable oils with short-chain fatty acids. These methods are not quantitative for the very volatile compounds such as naphthalene, acenaphthene and fluorene. Due to interferences provided by the matrix itself, palm oil and olive pomace oil cannot be analysed using this method. The quantification limit is 0,2 µg/kg for almost all compounds analysed, except for fluoranthene and benzo(g,h,i)perylene, where the quantification limit is 0,3 µg/kg, and indeno(1,2,3-c,d)pyrene, where the quantification limit is 1,0 µg/kg. NOTE The results for olive pomace oil in Annex B show that this method is not applicable to this type of oil. The precision data determined are very poor. Milk and milk products (or fat coming from milk and milk products) are excluded from the scope of this International Standard.

ISO 9936:2016 specifies a method for the determination of the contents of free α-, β-, γ-, and δ-tocopherols and tocotrienols (referred to jointly as tocols) in animal and vegetable fats and oils (referred to hereinafter as fats) by high-performance liquid chromatography (HPLC). For products containing tocopherol or tocotrienol esters, it is necessary to carry out a preliminary saponification. Milk and milk products (or fat coming from milk and milk products) are excluded from the Scope of this International Standard. NOTE A suitable method involving a cold saponification procedure is described in Annex B for information only.

ISO 6886:2016 specifies a method for the determination of the oxidative stability of fats and oils under extreme conditions that induce rapid oxidation: high temperature and high air flow. It does not allow determination of the stability of fats and oils at ambient temperatures, but it does allow a comparison of the efficacy of antioxidants added to fats and oils. The method is applicable to both virgin and refined animal and vegetable fats and oils. Milk and milk products (or fat coming from milk and milk products) are excluded from the scope of this International Standard. NOTE The presence of volatile fatty acids and volatile acidic oxidation products prevents accurate measurement.

ISO 6885:2016 specifies a method for the determination of the anisidine value in animal and vegetable fats and oils. This is a measure of the amount of aldehydes present (principally α, β-unsaturated aldehydes). Milk and milk products (or fat coming from milk and milk products) are excluded from the scope of this International Standard.

ISO 18363-1:2015 describes a procedure for the indirect determination of 3-MCPD esters (bound 3-MCPD) and possible free 3-MCPD after alkaline catalysed ester cleavage and derivatization with phenylboronic acid (PBA). Furthermore, this part of ISO 18363 enables the indirect determination of glycidyl esters (bound glycidol) under the assumption that no other substances are present that react at room temperature with inorganic chloride to generate 3-MCPD. ISO 18363-1:2015 is applicable to solid and liquid fats and oils. Milk and milk products (or fat coming from milk and milk products) are excluded from the scope of this part of ISO 18363.

ISO 17780:2015 specifies a method for the determination of saturated aliphatic hydrocarbons from C10 to C56 of natural origin present in vegetable oils, and for detecting the presence of mineral oil and diesel oil. The method is applicable to all types of crude and refined edible oils and fats, for concentrations of mineral oils from 50 mg/kg to 1 000 mg/kg. A rapid method for refined and virgin (or cold-pressed) oils is proposed in Annex C. This rapid method is not adapted for crude oils due to a lack of retention of triglycerides observed for some samples. A method for fat recovery from food samples by soxhlet extraction with a blend of solvents is proposed in Annex D.

ISO 12966-4:2015 specifies a method for the determination of fatty acid methyl esters (FAMEs) derived by transesterification or esterification from fats, oils, and fatty acids by capillary gas chromatography (GLC). Fatty acid methyl esters from C8 to C24 can be separated using this part of ISO 12966 including saturated fatty acid methyl esters, cis- and trans-monounsaturated fatty acid methyl esters, and cis- and trans-polyunsaturated fatty acid methyl esters. The method is applicable to crude, refined, partially hydrogenated, or fully hydrogenated fats, oils, and fatty acids derived from animal and vegetable sources. This method is not suitable for the analysis of dairy, ruminant fats and oils, or products supplemented with conjugated linoleic acid (CLA). Milk and milk products (or fat coming from milk and milk products) are excluded from the scope of this part of ISO 12966. ISO 12966-4:2015 is not applicable to di-, tri-, polymerized and oxidized fatty acids, and fats and oils.

ISO 12966-1:2014 gives an overview of the gas chromatographic determination of fatty acids, free and bound, in animal and vegetable fats and oils following their conversion to fatty acid methyl esters (FAMEs).

ISO 12228-2:2014 specifies a procedure for the gas chromatographic determination of the contents and composition of sterols and triterpene dialcohols in olive and olive pomace oils. For the determination of the contents and composition of sterols in all other animal and vegetable fats and oils, ISO 12228‑1 is to be used.

ISO 18301:2014 specifies a method for the determination of the conventional mass per volume of vegetable and animal oils and fats within the range of 0,800 kg/l to 1,000 kg/l which are in a single-phase liquid state at the test temperature. This method is not intended for use in calibrating online density meters.

ISO/TS 17383:2014 describes the procedure for the capillary gas chromatographic determination of the qualitative and semi-quantitative composition of individual triglycerides of fats, oils, and fat mixtures. The separation of the triglycerides is based on their retention depending on the carbon number of the fatty acids in the triglycerides and their degree of unsaturation. ISO/TS 17383:2014 is applicable to animal and vegetable fats, as well as to mixtures of natural and synthetic triglycerides, as long as the oil fatty acid composition does not contain high content of linolenic acid such as linseed oil and the total chain length does not exceed a total carbon number of C60.

ISO 12228-1:2014 specifies a procedure for the gas chromatographic determination of the content and composition of sterols in animal and vegetable fats and oils. However, the determination of the contents and composition of sterols in olive and olive pomace oils is to be carried out using ISO 12228-2.

ISO 17932:2011 specifies a method for the determination of the deterioration of bleachability index (DOBI) of crude palm oil and the carotene content of crude or bleached palm oil and their fractions by spectrophotometric examination in the ultraviolet and visible range of the spectrum.

ISO 3656:2011 specifies a method for the determination of the absorbance at ultraviolet wavelengths of animal and vegetable fats and oils.

ISO 27608:2010 specifies a method for the determination of Lovibond® colour of animal and vegetable fats and oils using automatic instrumentation.

ISO/TR 23647:2010 specifies a gas chromatographic method for determining the wax content of crude, degummed, neutralized, winterized, and fully refined vegetable oils, such as sunflower, soybean, rapeseed, corn, and rice bran oils. Waxes are esters of long chain fatty acids and fatty alcohols (having C20 or longer saturated carbon chain). The wax content is expressed in milligrams per kilogram of oil.

ISO 12873:2010 specifies the determination of the wax content, as a mass fraction expressed in milligrams per kilogram, of olive oils and olive-pomace oils. The individual waxes are separated according to the number of carbon atoms. The method is recommended for distinguishing between olive oil obtained by pressing or centrifuging and that obtained from olive pomace (olive-pomace oil).

ISO 12872:2010 specifies a procedure for the determination of the content, as a percentage mass fraction, of 2-glyceryl monopalmitate content in olive oils and olive-pomace oils that are liquid at ambient temperature (20 °C).

ISO 11701:2009 specifies a method for the quantitative determination of phospholipids content by high performance liquid chromatography (HPLC) using a diol column and a light-scattering detector. The method is applicable to crude, oil-containing lecithins, and to oil-free lecithins and lecithin fractions from vegetable fats and oils. The method is not applicable to animal and ruminant lecithins and enzymatically hydrolysed lecithins as the peak separation of lysophosphatidylethanolamine (LPE), lysophosphatidylinositol (LPI) and lysophosphatidic acid (LPA) is insufficient.

ISO 11053:2009 specifies a procedure for the detection and quantification of cocoa butter equivalents (CBEs) and milk fat in milk chocolate by triacylglycerol profiling using high-resolution capillary gas-liquid chromatography, and subsequent data evaluation by simple and partial least-squares regression analysis. CBE admixtures can be detected at a minimum level of 0,5 g CBE/100 g milk chocolate and quantified at a level of 5 % mass fraction CBE addition to milk chocolate with a predicted error of 0,7 g CBE/100 g milk chocolate.

ISO 22959:2009 specifies a high performance liquid chromatographic (HPLC) procedure for the determination of polycyclic aromatic hydrocarbons (PAHs) in edible fats and oils. The method has been validated for coconut, olive, sunflower, and soybean oil, and is possibly applicable to other oils, dependent on the determination of appropriate parameters. The lowest level of quantification for the PAHs is 0,1 µg/kg. The lowest possible amount of each PAH which can be distinguished from the baseline noise has not been determined. The validated concentration range of the method is 0,1 µg/kg to 3,5 µg/kg for each individual PAH. For samples containing (light) PAH contents > 3,5 µg/kg, dilution to bring the contents into the validated range is possible. It is also possible to adjust the range of the calibration curves. However, ranges exceeding 3,5 µg/kg have not been validated. PAHs which can be determined by this method are: anthracene, phenanthrene, fluoranthene, pyrene, chrysene, benzo[a]anthracene, benzo[e]pyrene, benzo[a]pyrene, perylene, benzo[ghi]perylene, anthanthrene, dibenzo[a,h]anthracene, coronene, indeno[1,2,3-cd]pyrene, benzo[a]fluoranthene, benzo[b]fluoranthene, benzo[k]fluoranthene.