engleski

Determination of adulteration of milk with milk powder using a modified spectrophotometric method

Milk production by adding milk powder or selling reconstituted milk powder as raw, pasteurized or UHT milk is one of the serious problems facing the dairy industry today. Adulteration, besides creating unfair market competition, misleads the consumer. The development of methods, in order to prevent product market failures that do not comply with legal regulations, is one of the key challenges in the protection of society. The aim of this paper was to modify the spectrophotometric method for determining the adulteration of drinking milk. The method includes degreasing of milk, coagulation of milk proteins by adding acetic acid, heating the formed curd in the presence of phosphomolybdic acid resulting in its blue staining. The intensity of the blue colour is proportionally increased by the addition of reconstituted milk powder and is measured spectrophotometrically at 620 nm. For semi- quantitative determination of the amount of added milk powder the calibration milk samples with known composition, produced from a mixture of raw or pasteurised or UHT milk with 0 ; 5 ; 15 ; 35 and 65 % (v/v) reconstituted milk powder were prepared, respectively upon analysed type of milk. The curd of unadulterated milk samples coloured greenish while the curd of adulterated milk samples with added milk powder coloured light to dark blue depending on the percentage of added milk powder. The molecular modelling methods were used to predict the clarification of staining mechanism of the formed curd and phosphomolybdic acid. The applied and modified spectrophotometric method was found to be suitable for the detection of milk adulteration by the addition of milk powder

milk adulteration ; milk powder ; reconstituted milk ; spectrophotometric method

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