BS EN ISO 17678:2019

What is ISO 17678-Determination of milk fat purity in milk and milk products about?

ISO 17678 discusses milk and milk products. ISO 17678 is an international standard on the determination of milk fat purity in milk and milk products to classify the milk for the preparation of derivatives.

ISO 17678 specifies a reference method for the determination of milk fat purity using gas chromatographic analysis of triglycerides.

The method specified by ISO 17678 applies to bulk milk, or products made thereof, irrespective of the variation in common feeding practices, breed, or lactation conditions. In particular, the method applies to fat extracted from milk products purporting to contain pure milk fat with unchanged composition, such as butter, cream, milk, and milk powder.

Note 1: Because a false-positive result can occur, the method specified under ISO 17678 does not apply to milk fat related to these circumstances:

• Obtained from bovine milk other than cow’s milk
• Obtained from single cows
• Obtained from cows whose diet contained a particularly high proportion of vegetable oils such as rapeseed, cotton, palm oil, etc
• Obtained from cows suffering from serious underfeeding (strong energy deficit)
• Obtained from colostrum
• Subjected to technological treatment such as removal of cholesterol or fractionation
• Obtained from skim milk, buttermilk, or whey
• Obtained from cheeses showing increased lipolysis
• 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)

Note2: 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.

Note3: 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.

Note4: 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. Moreover, grass-only diets such as mountain and 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.

Note5: In cases where a positive result is suspected to be caused by circumstances related to c) or d), another analytical method, such as fatty acid or sterol analysis, can be applied to confirm the finding.

Who is ISO 17678-Determination of milk fat purity in milk and milk products for?

ISO 17678 on the determination of milk fat purity is useful for:

• Food scientists
• Food technologists
• Food laboratories
• Food health and safety department

Why should you use ISO 17678-Determination of milk fat purity in milk and milk products?

Fat content determination in milk and milk products is significant because it impacts the price paid per litre of milk. It determines if a sample of milk or cheese complies with established legal values.

ISO 17678 provides you with methods and procedures to determine milk fat purity in milk and milk products. Fat extracted from milk or milk products is analyzed by gas chromatography to determine triglycerides.

The methods provided by ISO 17678 assist you to enhance the quality of milk and milk products and ensure that milk and milk products are safe for consumption.

By adopting ISO 17678 the user can efficiently determine the milk fat purity of milk and milk products.

What is changed since the last update?

BS EN ISO 17678:2019 supersedes EN ISO 17678:2010, which is withdrawn. BS EN ISO 17678:2019 has made some technical changes with respect to EN ISO 17678:2010. These include:

• The Scope has been restricted to exclude milk fat obtained from special feeding practices and whey
• The Scope has been extended to include milk fat obtained from cheese showing low lipolysis
• The normative references have been updated to reflect the modified scope
• A method has been added for the fat extraction from cheese