A disposable microbial based biosensor for quality control in milk

The food industry needs suitable analytical methods for quality control, that is, methods that are rapid, reliable, specific and cost-effective as current wet chemistries and analytical practices are time consuming and may require highly skilled labor and expensive equipment. The need arises from heightened consumer concern about food composition and safety. The present study was carried out keeping in view the recently emerging concern of the presence of urea in milk, called synthetic milk. The biocomponent part of the urea biosensor is an immobilized urease yielding bacterial cell biomass isolated from soil and is coupled to the ammonium ion selective electrode of a potentiometric transducer. The membrane potential of all types of potentiometric cell based probes is related to the activity of electrochemically detected product, and thus to the activity of the substrate by a form of the Nernst equation. Samples of milk were collected and analyzed for the presence of urea by the developed biosensor with a response time as low as 2 min. The results were in good correlation with the pure enzyme system. (C) 2003 Elsevier Science B.V. All rights reserved.