Rapid Non-Destructive Assessment of Aquatic Products Freshness by Gas Sensor Based on Morphology-Controlled SnO2 Hollow Nanosphere

Trimethylamine (TMA), a characteristic volatile biogenic amine generated during aquatic product spoilage, has a concentration that quantitatively reflects product freshness. Therefore, developing a rapid and accurate method for TMA detection is important for food safety control. Herein, this study synthesized high-performance hollow SnO2 nanospheres via a hydrothermal method, aiming to develop a rapid, non-destructive gas sensor for TMA detection and evaluate its feasibility for assessing aquatic product freshness. The material exhibited a high response (Ra/Rg = 10.5@100 ppm), rapid response-recovery kinetics (10 s/20 s), and good selectivity. These properties were attributed to the high specific surface area, efficient gas diffusion channels, and abundant active sites provided by the hollow structure, which enhances the sensor’s response rate. Ultraviolet–visible diffuse reflectance spectroscopy further showed that the hollow structure narrows the bandgap of SnO2, which may facilitate electron transfer and contribute to the enhanced response to TMA. In practical applications, a MEMS sensor based on SnO2 hollow nanospheres successfully detected TMA concentration changes from sea bass during 0–8 days of refrigerated storage, demonstrating its potential reliability for rapid freshness assessment of aquatic products and providing a technological route for quality evaluation.