Speckle Pattern Imaging for Recognition of Milk Dilutions

Milk adulteration is one of the more frequently reported food fraud and represents a global social and economic concern. One of most common type of counterfeiting is dilution with water. In this work., we report a simple but effective method to recognize different types of commercial cow milk and to detect if a whole milk sample has been diluted with water. The technique is based on the acquisition., by means of a CMOS camera., of speckle pattern images., generated by a red semiconductor laser. Data are then processed: the average intensity and the dimension of the speckle grains can be extracted. We then prove that., by considering both statistical parameters., it is possible to identify different milk type as well as diluted samples with a water fraction higher than 10%.