The Application of Gas Sensor Array based Electronic Nose for Milk Spoilage Detection

Microbial spoilage in milk is a crucial concern for healthy consumption. This study aims to apply the electronic nose system (e-nose) comprising an array of different gas sensors as an initial tool for monitoring of food spoilage for maintaining food safety and human health. In this system, nanocomposite gas sensors based on different polymers and functionalized single-walled carbon nanotubes (f-SWCNTs) are employed. By exposure of these gas sensors to the milk's headspace, the gas sensors show responsive signals toward volatile organic compounds (VOCs) contained in the milk. The pasteurized milks under two storage conditions, at 4°C (±1°C) and 25°C (± 1°C), were used to observe development of spoilage for 9 days. To consider the capability of electronic nose for freshness and milk spoilage detection, the odor pattern was analyzed using principal component analysis (PCA). The ability of each sensor to detect the intensity of the odor level was observed by tracking the change of sensing responses. The discrimination results have shown that the odor levels of samples stored at 4°C are not different from the first day to the ninth day, whereas the odor levels of samples stored at room temperature condition are increasing upon the storage time. The exploration in this work can thus provide information about the application of electronic nose with nanocomposite gas sensor array as a beneficial tool for monitoring the food spoilage and quality control.