Unraveling material characteristics of different pork belly cuts from raw to dish: a comparative study of texture and flavor

Pork belly is widely favored for its alternating fat-lean layers, yet the raw material characteristics of different cuts-upper (UPB), middle (MPB), lower (LPB), and second-knife meat (SKM)-remain unclear. This study selected twice-cooked pork belly (TPB) as the model dish to systematically compare the texture, collagen, microstructure, and flavor of four cuts from raw to cooked stages. Texture analysis showed that the skin layer was mainly related to collagen, while the fat layer was influenced not only by collagen content and composition but also by the extracellular matrix network, as revealed by Masson staining. Lean meat texture was primarily determined by its proportion, resulting in 57.55 ~ 124.45% higher chewiness in SKM. Flavor and precursor analysis revealed that UPB was characterized by higher proline and C20:4n6 and was associated with higher relative abundance of sweet/citrus aldehydes. MPB generated fatty aroma linked to C18:1n9c. LPB delivered complex meaty/roasted flavors from C18:1n9c, C18:2n6c, and Phe. SKM exhibited a flavor profile dominated by 2,3-butanedione due to its high branched-chain amino acid content. Furthermore, biplot analysis elucidated the relationships between raw material characteristics and final quality attributes, providing a theoretical basis for selecting the pork belly cuts in industrial production.