Development of immunometric test for detection of reconstituted (dry) milk adulteration of fresh milk

Summary
The adulteration of fresh milk by “dry” milk (reconstituted from powder) is a common problem in milk industry. The kit is based on monoclonal antibodies that recognize heat-sensitive neoepitope (neoantigen) of milk serum proteins that appear during heating. The degree of formation of target neoantigen strongly depends on heating time and temperature. Quantity of target neoantigen depends also on milk normalization strategies, drying and condensation parameters. Guaranteed fresh cow’s milk, treated by modern sterilization technologies (eg UHT) show absolute absence of target neoantigen; it allows to determine very sensitively the addition of dry milk or crude technology violations and/or adulterations.

Kit performance data (see also IFU):
Test principle: sandwich, monoclonal antibodies
Total time of analysis: 30/30/15 min
Sensitivity: 0.001 U/ml
Material tested: liquid milk, dairy products

Estimation of antigen presence in different sources

Sample type	Dry milk antigen U/ml	Comments
Control material
Fresh cow's milk	<0.001	Obtained during 3 hours after milking
Whole dry milk, 25%	>2	For food purposes
Normalized dry milk, 25%	>20
Dry milk, ultra heat treated	~100000	For research use only
Clabbered milk	<0.001	Naturally, or by acid treatment
Tested random from local supermarket
Heated fresh milk	50	During 6 hours at 90 C
UHT fresh milk, normalized	<0.001	Labelled as “dry milk FREE”
Sterilized fresh milk, normalized	<0.001