Real-time assessment of food freshness in refrigerators based on a miniaturized electronic nose

Food freshness has been paid great attention due to its direct relationship with human health and safety, and approaches for food freshness evaluation have attracted much interest from researchers. In this paper, we developed a miniaturized electronic nose system for convenient, direct and real-time food freshness evaluation by analyzing gases in a refrigerator (4 degrees C). The proposed system consists of a gas sampling module and MOS gas sensor array. The gas sampling module was used to extract gases from the refrigerator and clean the gas path by controlling a pump and a three-way valve. The gas sensor array is composed of three MOS sensors to monitor odor changes in the refrigerator. Meanwhile, a food freshness assessment model was established based on the sensor array results and a comparison with human sensory evaluation results. In order to confirm the effectiveness of the system, we performed experiments on meat, vegetables and fruits with three freshness levels including fresh, semi-fresh and spoiled. The accuracy of the system to identify the three freshness levels is 84.8%, 68.0% and 96.2% respectively. The experimental results demonstrated that the developed electronic nose can effectively evaluate the food freshness level. Therefore, the proposed electronic nose provides a non-destructive, low cost and convenient platform for fast and real-time evaluation of food freshness in refrigerators.