Food is a lot more than just a basic necessity to survive for many of us. Just a bite of some good food can help elevate mood and sometimes wash away stress. This is the reason why we make sure to stock up on certain foods to relish them at any time. But the only thing that stops us from hoarding too much of a certain edible food is that they are perishable. Foods such as cheese, meats, and eggs often have a shorter shelf life and get spoiled. Consuming rotten food can be harmful to health and pose certain risks. But you need not worry as there is a way you can tell if your apple is still fresh or if the eggs you bought a week ago can still be made into an omelette. No, it is not about the expiry date on the packet but scientists have developed a sensor which can detect if your food has spoiled or not.Also Read: New Sensor Detects Pesticide Residues On Fruits And VegetablesAn Indian student from Southern Methodist University in Texas, US, has created a flexible sensor which measures the pH level of foods to determine their freshness. According to Khengdauliu Chawang, who hails from Nagaland, the pH sensors work similarly to small wireless radio-frequency identification devices used in luggage tags.“Every time a food package with our device passes a checkpoint, such as shipping logistics centers, harbors, gates or supermarkets’ entrances, they could get scanned and the data could be sent back to a server tracking their pH levels,” said the PhD student.The sensor is 2 millimetres long and 10 millimetres wide which allows it to be incorporated into current food packaging methods.Also Read: Students Invent ‘Edible Tape’ To Keep Wrap Fillings IntactKhengdauliu Chawang explained that the freshness of the food is related to its pH levels. Foods that have a higher pH level than the normal range tend to be spoiled. This is because of bacteria and fungi in such environments. The sensor detects the hydrogen ions concentration in the food to measure the pH level.Chawang’s sensor has proven to be effective in determining the freshness of the food items such as honey, fruits, fish, and milk.Recently researchers from the Pusan National University also developed a similar device to check if a food is still fit for consumption. The device is a portable molecular sensor which detects the presence of biogenic amines (BAs) in food. BAs are a variety of low molecular nitrogen compounds that are released when food such as meat, cheese, and fish start to decompose.