Real-time detection of trimethylamine biomarker using acid-etched MOF-derived α-MoO3 nanoplates for non-destructive assessment of shrimp freshness.

Shrimp freshness directly determines product quality and food safety; however, achieving accurate, rapid, and non-destructive freshness assessment remains a significant challenge. This study developed acid-etched metal-organic framework (MOF)-derived α-MoO3 nanoplates for detecting trimethylamine (TMA), a key volatile marker of shrimp freshness, thereby enabling shrimp freshness assessment. The acid-etching activates lattice oxygen, converting it into surface chemisorption oxygen, while also mitigates the Lewis acidity around the Mo sites. Consequently, TMA-sensing tests utilizing this α-MoO3 nanoplate exhibits a notable selectiveness, clear response (Ra/Rg = 33.6-100 ppm), minimal detection threshold (MDT, 100 ppb), and rapid detection rate under a low temperature (160 °C). Importantly, using headspace solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS) for shrimp freshness detection, the content of TMA increases from 0 to 294.4 ppm within 0-12 h post-mortem. The detection results of this MoO3 sensor are in excellent agreement with those of the GC-MS analysis, validating the practical application value of this sensor. This work presents an efficient detection platform based on high-performance gas sensor for non-destructive seafood freshness assessment via biomarker monitoring.