Design and development of portable opto-electronic sensing system for real-time monitoring of food fermentation

The paper presents an optical based measurement system to monitor the fermentation process of food samples, such as raw milk, pasteurized milk, curd, grape juice and batter. The microbial growth during the fermentation and its effects in changing the parameters such as pH, dissolved oxygen, optical density and fluorescence are observed continuously by using minimal invasive optical sensing system. The sensing membranes for pH and dissolved oxygen are prepared using sol-gel technique and attached at an inner wall of a single-cell transparent container. The opto-electronic system is constructed to hold a single-cell transparent container along with light sources, detectors, signal processing circuits, computational and display unit. The performance characteristics, such as stability, response time and reproducibility are verified before it has been applied for food fermentation analysis. The developed optical sensor system shows the maximum relative error rate of 3.98% and a minimum of 0.21% for the pH measurement and for the dissolved oxygen measurement the relative error rate is observed between 0.36% and 3.75%. The results are found comparable and the proposed simple and cost effective system may be considered to monitor the food grades at the household level.