Formation and Prediction of PhIP, Harman, and Norharman in Chemical Model Systems Containing Epicatechin under Various Reaction Conditions

The aim of this study was to investigate the formation rules of 1-methyl-6-phenylimidazo[4,5-b]-pyridine (PhIP), 1-methyl-9H-pyrido[3,4-b]-indole (Harman), and 9H-pyrido[3,4-b]-indole (Norharman) in chemical model systems containing epicatechin under various reaction conditions and establish their prediction models. The results indicated that at 100–200 °C and pH 5.5–7.5 for 10–90 min, epicatechin inhibited the formation of PhIP, Harman, and Norharman by 32–100, 1–93, and 5–98%, respectively. The exponential growth equation in the growth model with R2 of 0.986–0.997, the second-order equation in the polynomial model with R2 of 0.900–0.949, and the trigonometric function equation in the Fourier model with R2 of 0.513–0.926 were well fitted for the formation of PhIP, Harman, and Norharman at various temperatures, times, and pHs, respectively. The calibration set (R2c) and the prediction set (R2p) of the optimal partial least squares regression prediction model was 0.74 and 0.70 for PhIP, 0.75 and 0.70 for Harman, and 0.90 and 0.91 for Norharman, respectively. The results provide theoretical support to develop technologies or equipment for the real-time synchronous monitoring of PhIP, Harman, and Norharman during meat processing.