Solution-blown PAN/Congo red nanofibrous sensors for colorimetric detection of soybean oil oxidation

Recognizing the importance of cooking oil quality and the potential health risks associated with oxidation, this study developed an indirect-contact nanofiber-based system for detecting cooking oil oxidation. The effects of spinning parameters on sensor sensitivity were investigated. Eight nanofiber mats (MAT I-VIII) were fabricated using different needle sizes (21 G and 18 G), polymer concentrations (12% and 15%), and air pressures (0.5 and 2 MPa). Congo red was incorporated into polyacrylonitrile (PAN) nanofiber mats using a solution-blowing technique. The mats were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and colorimetric analysis. Sensor performance was evaluated during soybean oil heating at 180 ± 2 °C for 7 h. Peroxide value, para-anisidine value, total oxidation value, and acid value were monitored as oxidation indicators. After 7 h, peroxide value, para-anisidine value, and acid value increased to 14.55 meq O₂/kg oil, 9.48, and 0.84 mg KOH/g, respectively. Nanofiber diameter strongly influenced oxidation detection. MATs VI-VIII, produced with the smaller 21 G needle, exhibited faster and more stable responses. MAT VIII (21 G, 15% PAN, 0.5 MPa) showed the most favorable sensitivity and response stability. The findings demonstrate the potential of PAN/Congo red nanofiber mats as an indirect-contact approach for visual monitoring of cooking oil oxidation.