Development of a Hardware Platform for Detection of Milk Adulteration Based on Near-Infrared Diffuse Reflection

Generally, detection of water adulteration in milk is performed using a cryoscope. However, the equipment may present erroneous results when other adulterants, e.g., urea, are added to milk. One of the techniques capable of overcoming situations in which the cryoscope fails to detect fraud is near-infrared (NIR) spectroscopy. Unfortunately, the development of an instrument based on this technology is challenging due to the influence of external factors and low signal-to-noise ratio. This paper presents a hardware platform based on NIR diffuse reflectance spectroscopy. It can be used to determine the concentration of substances in solid and liquid samples that present diffuse reflectance. An optical condenser system was developed using fixed lenses to increase the signal-to-noise ratio. LEDs with specific spectral emission were used as the light source. In addition, InGaAsSb sensors, which present rapid response and good sensitivity to the NIR spectrum, were used to detect diffusely reflected light. The proposed instrument was tested on milk samples adulterated with water. The results presented high coefficients of determination, higher than 0.99. Therefore, the developed system may be used for detection of milk adulteration. For this purpose, the system response for other variables as milk composition and addition of adulterants other than water must be studied.