INTRODUCTION

The method developed by Lumex researchers is intended for determination of the mass concentration of whey proteins in milk by capillary electrophoresis (CE). The obtained measurement results provide solutions of the following application tasks:

• record the whey protein pattern of cow’s milk;
• reveal the presence of reconstituted milk in whole pasteurized milk;
• identify milk origin from various dairy cattle.

One of the tests for authenticity of milk and dairy foods is the qualitative and quantitative composition of whey proteins and their ratio.
Caseins dominate in cow’s milk before its processing (about 80 % of total protein), whereas caseins are almost absent from whey composition, the main components of which are the following:

• β-lactoglobulins,
• α-lactalbumin,
• bovine serum albumin,
• immunoglobulins,
• lactoferrin and other minor proteins.

It is known that the protein composition in heat treated (pasteurized or sterilized) milk substantially differs from that in raw milk. Of the two basic whey proteins, β-lactoglobulin is the least resistant to heating. It has been ascertained that its content in powdered milk is small and decreases during long storage.

MEASURING METHOD

The method is based on preliminary preparation of whey, its subsequent separation, identification, and determination of analyzed сomponents by capillary electrophoresis. The proteins are detected at a wavelength of 205 nm.