Verification of decreased polycyclic aromatic hydrocarbon (PAH) levels in yoghurt during storage using isotopically-labelled PAHs

This study detected 24 types of PAHs in yoghurt during fermentation and storage using the QuEChERS pretreatment coupled with gas chromatography triple-quadrupole mass spectrometry (GC-QQQ-MS) method. Deuterated PAH8 standards were subsequently adopted to simulate and analyze the decreases in PAH levels during storage because PAH8 was identified as the suitable indicator of PAH levels and risks, based on correlation analysis and principal component analysis (PCA). The results showed that benzo[a]pyrene (BaP), PAH24 and toxic equivalent (TEQ) levels decreased by 14.81 %, 14.95 % and 16.15 % after fermentation, respectively. During storage, BaP, PAH8 and TEQ levels declined continuously, reaching the maximum decrease rates of 56.44 %, 68.32 % and 71.84 %, respectively. Besides, the significant losses in BaP-d12 and PAH8-d levels verified the downward trends in non-labelled PAHs, with maximum decrease rates of 72.78 % and 56.74 %, respectively. This study provides reliable evidence of the decreases in PAH levels in yoghurt during storage and helpful guidance for future analysis of PAH changes.