# Colorimetric detection of edible oil oxidation using PAN–Congo red nanofiber mats

## TL;DR

A new color-changing sensor made of nanofibers can quickly detect oil spoilage, offering a fast and affordable way to monitor edible oil quality in real time.

## Contribution

A novel PAN–Congo red nanofiber sensor for rapid, visual detection of lipid oxidation in edible oils.

## Key findings

- Mat_III (0.01% CR) showed the highest sensitivity with ΔE values of 12.83 in soybean oil and 9.83 in olive oil.
- Soybean oil showed greater oxidation than olive oil after 35 days of accelerated storage.
- The sensor provided rapid response times of 2.94 s and 4.71 s for soybean and olive oil, respectively.

## Abstract

Lipid oxidation significantly compromises the safety, nutritional quality, and shelf life of edible oils, while conventional analytical methods are costly, time-consuming, and unsuitable for real-time monitoring. This study presents a novel nanofiber-based colorimetric sensor for rapid visual detection of lipid oxidation in soybean oil (SBO) and extra virgin olive oil (EVOO) under accelerated storage conditions (70 °C for 35 days). Polyacrylonitrile (PAN) nanofiber mats containing Congo red dye (CR, 0.0025%, 0.005%, and 0.01%, w/w) were fabricated via solution-blowing spinning and characterized using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Oxidative deterioration was evaluated through conjugated diene (CD) and triene (CT) values, para-anisidine value (p-AnV), total polar compounds (TPC), volatile oxidation compounds, Rancimat induction period (IP), FTIR analysis, and cytotoxicity assays. Among the developed sensors, Mat_III (0.01% CR) exhibited the highest sensitivity, showing distinct color responses with ΔE values of 12.83 ± 0.20 in SBO and 9.83 ± 0.15 in EVOO, and rapid response times of 2.94 s and 4.71 s, respectively. After 35 days, CD, CT, and TPC increased to 3.83%, 0.96%, and 12.17% in SBO and 2.49%, 0.62%, and 7.83% in EVOO, while IP values decreased markedly, particularly in SBO, from 7.89 h to 2.04 h. Overall, these sensors offer a low-cost, rapid, and user-friendly approach for real-time oil oxidation monitoring.