L-Cysteine (L-Cys) serves as both an inhibitor of the carcinogen 1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and an enhancer of food flavor, supporting efforts to improve food safety and quality. Using a glucose/phenylalanine/creatinine model system, this study assessed the effects of varying L-Cys concentrations on PhIP inhibition and pyrazine flavor enhancement through UPLC-MS/MS and GC-MS analyses. The optimal PhIP reduction (82.8 %-83.1 %) was achieved with 20 mg and 100 mg of L-Cys, whereas the pyrazine enhancement peaked with 200 mg and 100 mg of L-Cys (50.54 %-99.16 % and 37.83 %-98.82 %, respectively). A partial least squares regression (PLS) model demonstrated strong predictive accuracy (R