Milk Reader / Milk detector

It is hard work to tell if an uncovered bottle of unfinished milk has gone bad, and drinking metamorphic milk by mistake can lead to health problems.
The ”Milk reader” can examine the acidity statistics of the milk using infrared ray and compare them with the standard so as to figure out if the milk is safe for drinking. What you have to do is just switching it on and point the infrared ray to the milk. The red light would lit if the milk is metamorphic and the green one would lit if the milk is fresh.