DETERMINATION OF MILK ALBUMINS - CASEINS IN DIFFERENT TYPE OF MILKS BY CAPILLARY ZONE ELECTROPHORESIS METHOD

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angličtina

Caseins are heterogeneous group of phosphoproteins, which represent approximately 80% of proteins in Milk. They have a significant effect on Milk coagulation - participate in the formation of cheeses. They determine their yield and quality. They also have nutritional importance and they are widely applied in food industry (emulsifiers, textural features, bleaches, etc.). Also different composition of caseins causes differences in the quality and quantity of cheeses produced. It is; therefore, necessary to monitor their composition and quantity in the milk. Capillary zone electrophoresis (CZE) was chosen as a simple, cheap and ecological method, which provides sufficiently accurate results about content of caseins in the milk. Fractions of caseins are separated in the capillary to the narrow zones after insertion direct high voltage. Zones of separated fractions are detected in the the bottom part of capillary. It was used non-coated fused silica capillary (total length 125 cm, afficient length 100 cm), high voltage 30 kV, UV-VIS detection at 214 nm. As an electrolyte was used phosphate buffer 0,2 M (set for pH 2,5), in urea 8 M, with 0,05 % (Hydroxypropyl)methyl cellulose. We successfully separated 6 fractions of caseins. In the sample of milk, caseins were precipitated (10 % acetic acid, set up to pH 4,6), fats were removed (wash with acetone) and the sample of caseins was lyophilized. The sample was dissolved in the reduction buffer (0,25 M Tris in 8 M Urea, with 0,1 M DTT, set for pH 8,8 and diluted with water 1:1). System was incubated at the laboratory temperature 30 min and analyzed Method was applied to determinate caseins in different type of cow milks. Different type of milk was chosen - processed UHT warming, pasteurized and milks from two group of cows, which had a different composition of diet. We compared total content of caseins, content of individual fractions.

Caseins, capillary zone electrophoresis, separation, nutrition, cow milk, milk albumins

DVOŘÁK, M.; VESPALCOVÁ, M.

28. 8. 2011

Univerzita Pardubice

Pardubice

978-80-7395-378-2

11th International Nutrition & Diagnostcs Conference, Book of Proceedings

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