DIN EN ISO 17678-2017 牛奶和奶制品. 甘油三酯气相色谱分析测定乳脂纯度(参考方法) (ISO / DIS 17678:2017);德文和英文版本prEN ISO 17678:2017
Milk and milk products - Determination of milk fat purity by gas chromatographic analysis of triglycerides (Reference method) (ISO/DIS 17678:2017); German and English version prEN ISO 17678:2017
This International Standard specifies a reference method for the determination of milk fat purity using gas chromatographic analysis of triglycerides. Both vegetable fats and animal fats such as beef tallow and lard can be detected. By using defined triglyceride equations, the integrity of milk fat is determined. Basically, the method applies to bulk bovine milk, or products made thereof, irrespective of feeding, 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. However, under the hereafter-mentioned circumstances a false positive result can be obtained. Hence, the method is not applicable to milk fat: a) obtained from single cows; b) obtained from cows which received an exceptionally high feeding of pure vegetable oils such as rapeseed oil; c) obtained from colostrum; d) that has undergone technological treatment such as removal of cholesterol or fractionation; e) obtained from skim milk or buttermilk; f) that has been extracted by using the Gerber, Weibull-Berntrop or Schmid-Bondzynski-Ratzlaff methods, or that has been isolated using detergents (e. g. BDI method). With these extraction methods, substantial quantities of partial glycerides or phospholipids can pass into the fat phase. Consequently, the scope of this International Standard excludes certain products and particularly cheese (additionally, the cheese ripening process itself can affect the fat composition to such a degree that a false positive result is obtained).