Comparative characterization of fatty acids and volatile substances in Chinese indigenous and hybrid pork in raw, cooked, and reheated states

Fatty acids and volatile substances in hybrid pork (Duroc × Landrace × Yorkshire; DLY) and four indigenous pork (Guangdong small-ear spotted; hill black; Beijing black, BB; and Qingyu) in raw, cooked, and reheated states were explored. The objectives were to determine odor differences between DLY and indigenous pork and the difference in changes after heating and reheating and to clarify the reasons for these changes. Results revealed that C 18:1 and C 20:4 fatty acids are the key to distinguishing DLY pork from indigenous pork. After cooking, the greatest decrease was observed in the proportion of polyunsaturated fatty acids in pork, and after reheating, monounsaturated fatty acids were detected, except in the BB pork. The substances that accounted for the difference between DLY and indigenous pork were 2,3-octadione, hexanal, 1-octen-3-ol, 2-nonanone (after heating), and (Z)-2-nonenal (after reheating). Reheating reduced the content of nonanal, 2,3-octandione, hexanal, and ( E , E )-2,4-decadienal, resulting in the deterioration of the aroma. In the DLY pork, the dramatic increase in the ( Z )-2-nonenal content may be the key factor. Principal component analysis identified that the difference in aroma between DLY and indigenous pork increased after reheating, but hierarchical cluster analysis showed that regardless of treatment, flavor difference was smaller between DLY and indigenous pork than among indigenous pigs. The analysis results show that differences in fatty acid content and oxidation path in unsaturated fatty acids were the reasons for the difference in aroma and the deterioration of flavor after reheating.