Transfer of cadmium from goat milk to cream and to rennet and lactic curds

摘要

Two groups of 3 Saanen goats received a normal diet for 4 weeks; then the animals were given a cadmium (Cd)-supplemented diet; one group was fed 2 mg centre dot kg~(-1) centre dot d~(-1) Cd (as cadmium chloride); the other group was fed 4 mg centredot kg~(-1) centre dot d~(-1). Every week, one day's milks were skimmed and then transformed into cheese curds either by rennet coagulation or by lactic acidification using Lactococcus lactis. Prior to Cd administration, milk Cd levels ranged from less than 0.2 to 0.3 #mu#g centre dot L~(-1). During Cd administration, Cd levels ranged from 0.85 to 4.6 #mu#g centre dot L~(-1) in the milks used for cheese making. The transfer of Cd from milk to cream and curds varied widely around mean values, but did notseem to be correlated with Cd concentration in the milk. The mean Cd concentration factor was 3.3 +- 0.7 in the cream, 3.5 +-0.5 in lactic curds and 5.6 +- 0.8 in rennet curds. A quarter of the Cd contained in the original milk was found in the cream (25.3 +- 6 percent), about 60 percent in the curds (59.0 +- 8.3 percent in rennet curds and 56.7 +- 7.7 percent in lactic curds). The present study confirms previous results regarding Cd concentration in dairy products, and shows that a Cd concentration higher than 5 #mu#g centre dot kg~(-1) in French cheese can only be explained by contamination during the cheese-making process.