A highly sensitive ethylene gas sensor based on PtO2-decorated SnO2 used to monitor the ripening and spoilage of fruits and vegetables that are stored at room temperature

Abstract

Ethylene (C₂H₄), a plant hormone, can accelerate the ripening of fruits and vegetables. It can also easily lead to over-ripening and even spoilage. Generally, fruits and vegetables are harvested at the mature but unripe stage to be shipped to a distant market or stored for a better price. During these processes, the concentration of ethylene should be monitored. Metal-oxide semiconductor-based gas sensors, which have the merits of low cost, scope for miniaturization, high sensitivity, good long-term stability and selectivity, have attracted the attention of researchers for a long time. Here, a highly sensitive ethylene gas sensor based on PtO₂-decorated SnO₂, with an operating temperature of 270 °C and detection limit of 60 ppb, has been fabricated. The ripening and spoilage of banana, nectarine, mango, apple, lemon, yard-long bean, bell pepper, eggplant and potato, stored at room temperature, were monitored using the sensor. The ethylene released by these fruits and vegetables was collected and tested using the sensor. According to the test results, the correlation between their optimum edible/spoilage date and their date of maximum ethylene release were found. Furthermore, it was found that the odour released by spoiled meat had no influence on the detecting ability of the sensor, which was tested by storing meat, fruits and vegetables together. The sensor has great potential to be applied in practice to monitor the ripening and spoilage of fruits and vegetables.