Real-Time Monitoring of Milk Fermentation Process Using Highly-Sensitive Fibre Bragg Grating Stress Sensor

Continuous monitoring of milk fermentation process during industrial yogurt production using pH metres is often cumbersome and inefficient technique. A simple, cost-effective and accurate alternative sensing technology is required for real-time monitoring. In this paper, we report real-time continuous monitoring of milk fermentation process and determine the fermentation end point during yogurt production using highly-sensitive fibre Bragg grating (FBG) stress sensor. Milk fermentation is monitored in real-time by analysing the shift in the Bragg wavelength of FBG stress sensor inserted into the milk corresponding to time-dependent gradual increase in applied stress on FBG stress sensor because of yogurt coagulation. Required sensitivities for an FBG sensor used for milk having 0% and 2.5% fat are around 3.03 and 3.01 pm/Pa, respectively. A proof of the concept of a smart alarm system (AS) for determination of the fermentation end point of yogurt is discussed in this work. This study presents a cost-effective, simple and non-destructive method for continuous real-time monitoring of milk fermentation process and determination of fermentation end point for small as well as large-scale production of yogurt.