Performance of a constant phase element (CPE) sensor to detect adulteration in cow-milk with whey

In this paper, the performance of a constant phase element (CPE) sensor has been studied for detecting adulteration of cow-milk with whey. Addition of whey in milk increases its volume and makes it acidic but the percentage of lactose content does not change significantly. Hence, addition of neutralizers like NaOH will balances the pH value of the adulterated milk and increases the shelf life. Sometimes cheap muriatic acid (used for cleaning purpose) is added to the milk to prepare whey. Both muriatic acid and NaOH causes serious health hazards. In this work, the CPE sensor has been used to detect the adulteration of cow-milk with whey which contains muriatic acid and the neutralizer, NaOH. The sensor performances are observed in pure milk (pH- 6.74), milk adulterated with 60%, 120% and 180% of whey (pH value of whey is 6.02). The pH value of adulterated milk with 180% whey is 6.44. Finally NaOH is added to bring back the pH value to 6.74. At every stages of adulteration the CPE sensor is used and the results show that the sensor can successfully detect them. Finally, an electrical equivalent circuit of the sensor dipped-in the adulterated milk is proposed through complex non-linear least square (CNLS) method to facilitate the design of suitable signal conditioning circuit.