Detection of the Presence of Reconstituted Milk in Raw Milk and in Pasteurized Milk Using Synchronous Fluorescence Spectroscopy

The increasing demand for dairy products has led to the adulteration of milk with reconstituted milk. This may be a problem for unsuspecting consumers. In this study, synchronous fluorescence spectroscopy was used to detect the adulteration of raw milk and pasteurized milk by the addition of reconstituted milk. Milk samples were prepared by the precipitation of casein with a pH 4.6 buffer solution to separate the whey protein. Synchronous fluorescence spectra were then captured over an excitation wavelength between 200 and 500 nm at a wavelength interval (Δλ) of 75 nm. The raw data of the spectra were then subjected to a second derivative, and the ratio of the peaks of characteristic Maillard reaction products and tryptophan (2nDFM/T) were used to detect the adulteration of raw and pasteurized milk with reconstituted milk. This method is unaffected by variations in environmental temperature. The results indicate that the detection of reconstituted milk in raw and pasteurized milk can be achieved with an accuracy of 86.7 and 90%, while linear equations could be used to estimate the content range of reconstituted milk roughly according to the fluorescence data.