A novel 3D-printed flexible electrode with rGO/MWCNTs ink for capsaicin detection in chilli peppers

Capsaicin, the primary bioactive compound responsible for the pungency in chilli peppers, poses potential health risks at excessive levels. This study introduced a novel approach for capsaicin detection in food products using a reduced graphene oxide and multi-walled carbon nanotubes (rGO/MWCNTs)-based conductive ink integrated electrodes (IDE) produced via inkjet printing. A hybrid ink was synthesized by dispersing rGO and MWCNTs in polyethylene glycol 400, with the mass ratio of 1:2 to facilitate electron transfer. The rGO/MWCNTs-printed IDE sensor provided a dynamic range of 0.1 μM to 100 μM and a detection limit as low as 0.035 μM. The sensor exhibited good repeatability and selectivity, and maintained 97.5% of its initial response over 28 days. Practical applicability was validated in red, green, millet chilli pepper extracts and hotpot seasoning, yielding recoveries of 92.71–108.48%. The printed rGO/MWCNTs IDE platform enables sensitive capsaicin analysis and is suitable for food quality control