BS EN ISO 17678:2019 - Milk and milk products. Determination of milk fat purity by gas chromatographic analysis of triglycerides

BS EN ISO 17678:2019

Milk and milk products. Determination of milk fat purity by gas chromatographic analysis of triglycerides

Status : Current   Published : July 2019



This document specifies a reference method for the determination of milk fat purity using gas chromatographic analysis of triglycerides. The method utilizes the differences in triglyceride fingerprint of milk fat from the individual triglyceride fingerprints of other fats and oils to determine samples which are outside the range normally observed for milk fat. This is achieved by using the defined triglyceride formulae based on the normalized weighted sum of individual triglyceride peaks which are sensitive to the integrity of the milk[6][7]. The integrity of the milk fat can be determined by comparing the result of these formulae with those previously observed for a range of pure milk fat samples[12]. Both vegetable fats and animal fats such as beef tallow and lard can be detected. The method is applicable to bulk milk, or products made thereof, irrespective of the variation in common feeding practices, breed or lactation conditions. In particular, the method is applicable to fat extracted from milk products purporting to contain pure milk fat with unchanged composition, such as butter, cream, milk and milk powder. Because a false-positive result can occur, the method does not apply to milk fat related to these circumstances: a) obtained from bovine milk other than cow's milk; b) obtained from single cows; c) obtained from cows whose diet contained a particularly high proportion of vegetable oils such as rapeseed, cotton or palm oil, etc.; d) obtained from cows suffering from serious underfeeding (strong energy deficit); e) obtained from colostrum; f) subjected to technological treatment such as removal of cholesterol or fractionation; g) obtained from skim milk, buttermilk or whey; h) obtained from cheeses showing increased lipolysis; i) extracted using the Gerber, Weibull?Berntrop or Schmid?Bondzynski?Ratzlaff methods, or that has been isolated using detergents (e.g. the Bureau of Dairy Industries method). With the extraction methods specified in i), substantial quantities of partial glycerides or phospholipids can pass into the fat phase. NOTE 1 In nature, butyric (n-butanoic) acid (C4) occurs exclusively in milk fat and enables quantitative estimations of low to moderate amounts of milk fat in vegetable and animal fats to be made. Due to the large variation of C4, for which the approximate content ranges from 3,1 % fat mass fraction to 3,8 % fat mass fraction, it is difficult to provide qualitative and quantitative information for foreign fat to pure milk fat ratios of up to 20 % mass fraction[11]. NOTE 2 In practice, quantitative results cannot be derived from the sterol content of vegetable fats, because they depend on production and processing conditions. Furthermore, the qualitative determination of foreign fat using sterols is ambiguous. NOTE 3 Due to special feeding practices such as those related to c) and d), false-positive results have sometimes been reported for milk from certain Asian regions[15]. Moreover, grass-only diets such as mountain and, in particular, highland pasture feeding sometimes cause false-positive results, which can be substantiated by a content of conjugated linoleic acid (C18:2 c9t11) of ? 1,3 % fatty acid mass fraction[16][17]. Nevertheless, results conforming to the criteria of milk fat purity specified in this document are accepted, even if samples were undoubtedly produced under conditions reported in this note, including those described in h). NOTE 4 In cases where a positive resu

Standard NumberBS EN ISO 17678:2019
TitleMilk and milk products. Determination of milk fat purity by gas chromatographic analysis of triglycerides
Publication Date10 July 2019
Normative References(Required to achieve compliance to this standard)ISO 1211, ISO 1740, ISO 3696, ISO 7328, ISO 2450, ISO 1736, ISO 14156
Informative References(Provided for Information)ISO 5725-2, ISO 5725-1, ISO 707, ISO 835, BS 410 (all parts), ISO 3310 (all parts)
ReplacesBS EN ISO 17678:2010
International RelationshipsEN ISO 17678:2019,ISO 17678:2019
Draft Superseded By17/30367120 DC
DescriptorsPurity, Interferences (chemical), Fat content determination, Cream (dairy products), Powdered foods, Butter, Fats, Chemical analysis and testing, Fatty acids, Milk, Gas chromatography, Determination of content, Dairy products
Title in FrenchLait et produits laitiers. Détermination de la pureté des matières grasses laitières par analyse chromatographique en phase gazeuse des triglycérides
Title in GermanMilch und Milcherzeugnisse. Bestimmung der Reinheit des Milchfetts durch gaschromatographische Triglyceridanalyse (Referenzverfahren)
ISBN978 0 580 51563 7
File Size2.085 MB

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