Characterisation and formation mechanisms of aroma-active compounds in Tibetan pork: exploring the relation with precursors and cooking methods

With global meat consumption on the rise, pork has become a preferred protein source in China. Among the various pork types, indigenous Tibetan pork is highly valued for its unique geographical origin and distinctive quality attributes. These “superior attributes” elevate its market value and allow it to command premium prices, but they also increase the risk of food fraud, as some producers mislabel ordinary pork as Tibetan. Ensuring the authenticity of Tibetan pork is therefore critical for both consumer trust and economic integrity. Aroma is a key factor in pork quality perception and can serve as a potential marker for authenticity. This thesis investigates the relationships between aroma precursors in raw Tibetan pork and the volatile aroma compounds formed during cooking. The research aims to identify unique biochemical markers that can distinguish Tibetan pork from commercial variants, while also exploring how different cooking methods affect aroma compound formation. Lipidomics and proteomics approaches were employed to understand the formation mechanisms of aroma-active compounds and to support pork authentication. This thesis firstly identifies Tibetan pork’s distinctive precursor composition—particularly higher levels of omega-3 polyunsaturated fatty acids (PUFAs), branched-chain amino acids (BCAAs), and thiamine—compared to commercial pork. These markers enabled 100% accuracy in differentiating Tibetan pork by breed and region during standardised boiling. Subsequently, the impact of three cooking methods: sous-vide (SV), pan-frying (PF), and oven-roasting (OR), on aroma development is examined in further chapters. SV primarily promotes aroma formation through lipid oxidation, particularly from linoleic acid. PF generates aroma-active compounds through Strecker degradation and pyrazine formation from BCAAs. OR results in enhanced production of sulfur-containing Maillard byproducts and retains high levels of omega-3 PUFAs, suggesting high-temperature cooking methods are most effective in highlighting Tibetan pork's unique qualities. The last two chapters delve deeper into aroma formation mechanisms. Lipidomics analysis in shows that free fatty acids and phospholipids are key aroma precursors, particularly under low-temperature cooking where iron plays a pro-oxidative role. High-temperature methods, in contrast, initiate lipid oxidation early and facilitate Maillard reactions through haem iron denaturation. Proteomics analysis is applied to assess protein and myoglobin oxidation, Maillard reaction dynamics, and amino acid metabolism across cooking methods. OR demonstrates the highest oxidative activity, while SV shows the lowest due to vacuum packaging. These molecular changes significantly influence the generation of aroma-active compounds.