IDENTIFICATION OF AUTHENTICITY OF MILK POWDER USING THERMAL ANALYSIS AND ELECTRON MICROSCOPY

Possibility of application of methods of scanning electron microscopy and the combined method of thermal analysis including differential thermal analysis and thermogravimetry to identify the authenticity of dried whole and nonfat milk has been studied. Three samples of dried whole milk and two samples of skimmed milk powder were used as the objects of study. When using scanning electron microscopy particles of elongated shape with a size from 100 to 400 microns have been detected in three samples. Using the reaction with Lugol's reagent the presence of starch has been revealed in these samples. When using the method of differential thermal analysis an identification index of milk powder is an endoeffect at 200 °C associated with thermal decomposition of lactose. It is possible to determine a mass fraction of starch in the sample of milk powder when comparing the value of endoeffect of thermal decomposition of dehydrated amylose and amylopectin for a sample and starch. The studies have found adulteration caused by adding starch in 60% of samples of skim and whole milk powder.