Determination of phospholipids in soybean oil using a phospholipase-choline oxidase biosensor based on g-C3N4-TiO2 nanocomposite material

In this paper, we constructed a photoelectrochemical biosensor with ITO electrode as the reaction platform, g-C3N4 and TiO2 as the reaction substrate, Nafion solution as the cross-linking agent, dropwise addition of choline oxidase (ChOx) and optimized its preparation and detection conditions, and finally used this photoelectrochemical biosensor for the detection of Phosphatidylcholine (PC) in actual soybean gross oil. The experiments showed that the PC concentration showed a good linear relationship with the photocurrent response value in the range of 0.05–280 mg/L, and the limit of detection was 0.05 mg/L (S/N = 3). Under the optimized conditions, the sensor had the highest photocurrent response value and the best sensitivity for the artificially simulated gross oil; Phosphatidyl ethandamine (PE), Phosphatidic acid (PA) and Phosphatidyl inositol (PI) showed no significant interference for the detection of PC, and the sensor showed high selectivity for PC detection. The results showed that the relative photocurrent value of the sensor remained at a high level during the storage time of about 32 days, which proved that the electrode storage stability was good, and provided a theoretical basis for the establishment of a fast, accurate and low-cost method for the determination of the PC content, which could more accurately reflect the rule of change of PC in the catalytic reaction of soybean oil degumming, and further realise the precise and moderate processing of fats and oils.