Optical sensing system for detecting water adulteration in milk

Abstract

There has become an ever increasing need for detecting good quality of milk against the bad one because of the vast number of methods now known and used for milk adulteration. Especially since India has a vast and thriving dairy industry committing an adulteration fraud can reap rich profits and exploit poor people if undetected. Traditional methods involve measuring the specific gravity (e.g. Lactometer). But if the weight after introducing the adulteration is kept constant, such methods fail. The ones that have overcome this flaw and are presently prevalent are contact based methods that involve contact with the milk samples and hence the samples cannot be used again. Such methods lead to large amount of wastage of milk since the reliability seen thus far does not guarantee accurate adulteration detection within short number of tests. This paper proposes a completely non-contact type method for detection of milk adulteration, preserving the consistency and quality of milk sample and making it reusable for testing again. About 500 raw milk samples were considered for the study and categorized into 3 categories namely Cow milk, Buffalo milk, skimmed milk. Fresh samples obtained were from different dairies and commercial local brands like Saras, Anand, Amul etc. An embedded system consisting of AVR micro-controller integrated with the optical sensor, LCD and keypad was built. Refractive index was the principle parameter involved in detecting the adulteration. As the amount of water adulteration changed, the refractive index changed and these relations were used to configure the system for detecting adulteration of a random milk sample. The results obtained detected the adulteration with an accuracy of about 95 ± 1% which show an increase in misclarification accuracy of about 200% over traditional methods such as spectroscopy.