Detection of Adulterants in Milk Using Near Infrared Spectroscopy

Adulteration of natural milk by synthetic milk, prepared by mixing appropriate amount of vegetable oil, urea, detergent powderlshampoo, caustic soda, sugar/salt and skim milk powder to water has been reported recently. Detection of adulterants is difficult by a single method and sometimes more than two methods are required to confirm the presence. The potential of near-infrared spectroscopy (NIRS) in the wavelength range of 700-1124.8 nm for the purpose were investigated. Transmittance spectra of 125 adulterated samples prepared in laboratory were obtained using a spectrometer (MMS1, Zeiss, Germany) and analysed in the Unscrambler (CAMO, Trondheim, Norway) software. The best range of wavelengths for prediction model for milk, urea, NaOH, oil, and shampoo components were found to be 926.6 to 939.4, 996.6 to 1021.8, 945.8 to 977.6, 926.6 to 961.7, and 933.0 to 945.8 nm, respectively. Low standard errors indicated that NIRS has good potential to detect the adulterants in milk.