Effect of Variable-Temperature Roasting on the Color, Tenderness, Heterocyclic Amine and Polycyclic Aromatic Hydrocarbon Contents of Xinjiang Nang Pit-Roasted Lamb Meat

The purpose of this study was to optimize the roasting process for Xinjiang Nang pit-roasted lamb meat and explore the effects of variable-temperature roasting on the roasting loss percentage, color, tenderness, and heterocyclic aromatic amine (HAA) and polycyclic aromatic hydrocarbon (PAH) contents of roasted lamb meat.

The three-stage variable-temperature roasting process involving high temperature (T₁), roasting time (t₁), medium temperature (T₂), roasting time (t₂), low temperature (T₃), and roasting time (t₃) was optimized using an L₂₇ (3⁶) orthogonal array design and fuzzy mathematics comprehensive evaluation method. The differences in the contents of HAAs and PAHs in lamb meat roasted at variable temperature (CK), high temperature (HT) and low temperature (LT) were analyzed.

The decreasing order of the influence of variable-temperature roasting parameters on the sensory evaluation of roasted lamb meat was as follows: T₁ > t₂ > T₂ > t₁ > t₃ > T₃. The optimal roasting parameters were T₁ = 300 ℃, t₁ = 4 min, T₂ = 220 ℃, t₂ = 6 min, T₃ = 100 ℃, t₃ = 7 min, and the sensory score of lamb meat roasted under these conditions was 3.408 out of 4 points. There was a significant positive correlation between roasting loss percentage and T₂ (r = 0.50), between shearing force and T₁ (r = 0.47), between internal L* value and t₁ (r = 0.57), between surface a* value and sensory evaluation (r = 0.64), and between surface b* value and roasting loss percentage (r = 0.40). The total content of HAAs in roasted lamb meat was in decreasing order of HT > LT > CK. The highest roasting temperature in the CK group was the same as that in the HT group, but the total content of HAAs in the CK group was significantly lower than that in the HT group (P < 0.05). There was no significant difference in the total amount of HAAs between the LT and CK groups (P > 0.05). Principal component analysis of the total amounts of HAAs in the HT, LT and CK groups showed that the substances with the highest contribution rate to the first principal component (PC1) were 2-amino-3,4-dimethylimidazo[4,5-ƒ]quinolone (MeIQ), 2-amino-3-methylimidazo[4,5-ƒ]quinoxaline (IQx) and 2-amino-3,7,8-trimethylimidazo[4,5-ƒ]quinoxaline (7,8-DiMeIQx), respectively. The total content of PAHs in the HT group was (427.45 ± 27.84) ng/g, which was significantly higher than that in the LT and CK groups (P < 0.05). The substances with the largest contribution rate to PC1 and the second principal component (PC2) were phenanthrene (Phe) and benz[a]anthracene (BaA) for the LT group, respectively, and the substance with the largest contribution rate to PC1 were BaA for the CK group.

High-temperature roasting temperature is the key factor affecting the eating quality of lamb meat roasted at variable temperature, and variable-temperature roasting effectively reduces the total content of HAAs and PAHs in roasted lamb meat.