Analysis of Polycyclic Aromatic Hydrocarbons via GC-MS/MS and Heterocyclic Amines via UPLC-MS/MS in Crispy Pork Spareribs for Studying Their Formation during Frying

Abstract

This study aims to explore the effects of frying conditions on the formation of HAs and PAHs in crispy pork spareribs, a popular meat commodity sold on Taiwan's market. Raw pork spareribs were marinated, coated with sweet potato powder, and fried in soybean oil and palm oil at 190 °C/6 min or 150 °C/12 min, followed by an analysis of HAs and PAHs via QuEChERS coupled with UPLC-MS/MS and GC-MS/MS, respectively. Both HAs and PAHs in pork spareribs during frying followed a temperature- and time-dependent rise. A total of 7 HAs (20.34-25.97 μg/kg) and 12 PAHs (67.69-85.10 μg/kg) were detected in pork spareribs fried in soybean oil and palm oil at 150 °C/12 min or 190 °C/6 min, with palm oil producing a higher level of total HAs and a lower level of total PAHs than soybean oil. The content changes of amino acid, reducing sugar, and creatinine played a vital role in affecting HA formation, while the degree of oil unsaturation and the contents of precursors including benzaldehyde, 2-cyclohexene-1-one, and trans,trans-2,4-decadienal showed a crucial role in affecting PAH formation. The principal component analysis revealed that HAs and PAHs were formed by different mechanisms, with the latter being more liable to formation in pork spareribs during frying, while the two-factorial analysis indicated that the interaction between oil type and frying condition was insignificant for HAs and PAHs generated in crispy pork spareribs. Both CcdP (22.67-32.78 μg/kg) and Pyr (16.70-22.36 μg/kg) dominated in PAH formation, while Harman (14.46-17.91 μg/kg) and Norharman (3.41-4.55 μg/kg) dominated in HA formation in crispy pork spareribs during frying. The outcome of this study forms a basis for learning both the variety and content of HAs and PAHs generated during the frying of pork spareribs and the optimum frying condition to minimize their formation.

Keywords: GC-MS/MS; QuEChERS; UPLC-MS/MS; crispy pork spareribs; frying; heterocyclic amines (HAs); polycyclic aromatic hydrocarbons (PAHs).

Figure 1

Processing steps of crispy pork spareribs and their appearance after frying in soybean oil or palm oil at different temperatures and time lengths.

Figure 2

UPLC-MS/MS chromatograms of 21 HA standards as detected in selected reaction monitoring (SRM) mode. The gray portion represents peak area used for quantitation.

Figure 3

UPLC-MS/MS chromatograms of 5 HAs in crispy pork spareribs after frying in palm oil for 190 °C/6 min as detected in selected reaction monitoring (SRM) mode. The gray portion represents peak area used for quantitation.

Figure 4

Contents of HA precursors including reducing sugar (A), creatine (B), and creatinine (C) in crispy pork spareribs as affected by oil type and processing condition. ‘nd’ denotes that the reducing sugar value is not detected. The different small letters (a–e) on each bar represent significantly different values (p < 0.05) within each bar graph.

Figure 5

GC-MS/MS chromatograms of 24 PAH standards including internal standard (IS) as detected in selected reaction monitoring (SRM) mode. Peaks: 1, NaP; 2, AcPy; 3, AcP; 4, Flu; 5, Phe; 6, Ant; 7, FL; 8, Pyr; 9, BcF; IS, 4,7,8-TriMeIQx; 10, BaA; 11, CHR; 12, MCH; 13, BbF; 14, BjF; 15, CcdP; 16, BaP; 17, IP; 18, DBahA; 19, BghiP; 20, DBalP; 21, DBaeP; 22, DBaiP; and 23, DBahP.

Figure 6

GC-MS/MS chromatograms of 11 PAHs in crispy pork spareribs after frying in soybean oil for 150 °C/12 min as detected via selected reaction monitoring (SRM). The gray portion represents peak area used for quantitation.

Figure 6

GC-MS/MS chromatograms of 11 PAHs in crispy pork spareribs after frying in soybean oil for 150 °C/12 min as detected via selected reaction monitoring (SRM). The gray portion represents peak area used for quantitation.

Figure 7

Principal component analysis illustrating score plot (A) and biplot containing loading plot and score plot (B) for HA and PAH formation in crispy pork spareribs as affected by oil type and frying condition. u and m represent the amount of HAs or PAHs formed in unprocessed raw pork spareribs and marinated raw pork spareribs before frying, respectively; S1 and S2 represent the amount of HAs or PAHs formed in soybean oil-fried pork spareribs at 150 °C/12 min and 190 °C/6 min; P1 and P2 represent the amount of HAs or PAHs formed in palm oil-fried pork spareribs at 150 °C/12 min and 190 °C/6 min; S and P represent the amount of HAs or PAHs formed regardless of temperature/time length during frying of pork spareribs in soybean oil and palm oil; and t1 and t2 represent the amount of HAs or PAHs formed regardless of oil type during frying of pork spareribs at 150 °C/12 min and 190 °C/6 min. The dot (•) symbol denotes principal component data for the formation of HAs or PAHs in crispy pork spareribs during frying. The asterisk (∗) symbol indicates the highly formed individual HA or PAH as affected by different oil types and processing conditions. H1, DMIP; H4, Norharman; H5, Harman; H8, PhIP; H9, Trp-P-1; P2, Pyr; P4, BaA; P5, BbF; P6, BjF; P7, CcdP; P9, DBahA; P11, DBaiP.