Rapid on-site quantification of total polar materials in edible oils via a polarity-triggered fluorescent probe and smart 3D-printed sensing platform.

Edible oil is a crucial component of human dietary nutrition, and its safety directly impacts public health. Total polar materials (TPM) are a key indicator of oil degradation. However, restaurants and food processing facilities often lack the tools to quickly and accurately assess TPM levels, hindering effective oil management to reduce costs while ensuring oil quality and safety. In this study, we designed and synthesized a merocyanine-based probe, which is driven by microenvironmental polarity to exhibit a fluorescence "turn-on" response. The TPM content can be evaluated by the ratio of red fluorescence from the probe to the green fluorescence of the oil sample, producing a visually distinguishable transition from red to yellow-green. By integrating the probe into a portable, 3D-printed device with RGB detection analysis, we developed a portable quantitative analysis box for TPM testing in unknown oil samples. Chromatographic validation demonstrated that the device achieves high accuracy with a recovery rate of 97.56-109.29%. This cost-effective solution (under $20) enables real-time, on-site TPM monitoring, providing a promising tool for food safety control.