The Application Research On Research On Real-time Detection And Assessment Of Food Freshness In Refrigerator Based On An Intelligent Electronic Nose

Food freshness is of great concern due to its direct relevance to human health and safety.The traditional food freshness detection method owns the disadvantages of complicated operation,long detection time and subjective disturbance.The electronic nose detection method has the advantages of being portable,non-destructive,and real-time.In recent years,many studies have used electronic noses for food freshness recognition,while few examples of electronic noses combined with refrigerators for food freshness evaluation were reported.Therefore,this paper developed a small electronic nose system for real-time in situ detection of food freshness in refrigerator.The major research contents and innovations of this paper are as follows:1.Through in-depth study of food spoilage characteristics gases and refrigerator food freshness detection methods,this paper identified the detection of food freshness markers and refrigerator food pumping detection methods.We found out the main volatile organic gas compound components produced during food storage process by relevant literature.Then,we analyzed the gases produced by different food types according to GC-MS experiments and make certain the target gases that electronic nose needs to detect including ammonia,hydrogen sulfide and ethanol.The diffusion detection method and pumping detection method are designed for food freshness detection in refrigerator.By analyzing advantages and disadvantages of two detection methods,the pumping detection method is adopted.Based on this detection method,a miniaturized electronic nose system is designed.2.The design and optimization of food freshness detection sensor array was proposed.The MOS sensor type was determined and the sensor array for food freshness detection in refrigerator was constructed.The Metal Oxide Semiconductor(MOS)sensor was selected as the electronic nose detection sensor.The gas sensing mechanism and mathematical model of the MOS sensor were analyzed and sensor signal detection circuit was designed.For the three kinds of food freshness detection target gases,an electronic nose sensor array for food freshness detection in the refrigerator was designed.Environmental testing and food spoilage testing were carried out on the sensor array.The experimental results show that the MOS sensor array is effective in low temperature environment and has good sensitivity which can be used for food freshness detection in refrigerators.3.According to the modularity and miniaturization design requirements in practical applications,the hardware and software design of the electronic nose detection of the refrigerator food freshness is completed.This paper developed an electronic nose system for refrigerator food freshness detection.Considering the miniaturization and modular design of the electronic nose system,the electronic nose system design is mainly divided into gas path module,detection and control module and system software module.The gas path module includes sensor detection chamber,gas path controlling.Detection and system hardware circuit includes sensor signal detection circuit,MCU circuit,and gas path controlling circuit.System software module includes data acquisition and transmission,display and processing on PC,and food freshness recognition algorithms.4.Actual test of electronic nose and evaluation model of the food freshness in refrigerator was completed.Experiment results of food freshness detection and discrimination showed that the electronic nose can achieve good detection effect.Different concentrations standard gas obtained from gas distribution meter was used to calibrate the designed electronic nose system.The calibration results show that the designed system has a good concentration discrimination of target gases.Pork,leeks and bananas were selected for the refrigerator food experiments.The experimental results show that the designed electronic nose system has good sensitivity to the freshness change of the food in the refrigerator.At the same time,the food freshness in the refrigerator was divided into fresh,sub-fresh and corrupt according to the human sensory evaluation results.The preliminary discriminant model of refrigerator food freshness was established by linear discriminant algorithm.Experiments have been carried out and the results show that the recognition model can obtain better results.