Effects of pre-conditioning combined with innovative grilling processes on myofibrillar protein microstructure, volatilome shifting, and heterocyclic amine formation in duck meat.

This study investigates the effects of pre-conditioning processes matched with novel meat grilling treatments, including electrical heating (HT), microwave (MW), and infrared, on protein structural changes, oxidative degrees, formation of heterocyclic amines (HCA) and related precursor substances in duck meat. The underlying mechanisms of HCA formation were explored in conjunction with volatile flavor compound analysis. The results demonstrate that heat-induced methods significantly influenced the secondary structure of proteins, reducing α-helix and β-sheet contents while increasing random coil structures. Pre-conditioning processes decreased the formation of random coils. Electric grilling of pre-conditioned meat (HTP) significantly induced protein unfolding and promoted the oxidation of proteins and lipids, with the highest oxidative degree observed in HTP samples. The pre-conditioned processes further promoted oxidation, which was positively correlated with HCA formation. Browning intensity and 5-hydroxymethylfurfural characterization indicated that the Maillard reaction was most pronounced in HTP samples, followed by the infrared and microwave-heated samples, with pre-conditioning enhancing the Maillard reaction. HT exhibited the greatest reduction in creatine, while MW-treated samples retained the highest level of reducing sugars; infrared-heated samples exhibited intermediate levels of creatine and reducing sugars, which were further reduced by the pre-conditioning process. The highest total HCA content was observed in the HT group, with higher accumulation as observed in pre-conditioned samples, validating that HCA formation was jointly driven by the depletion of precursor substances and the promotion of oxidation. The orthogonal projections to latent structures discriminant analysis identified aldehydes, ketones, and pyrazines as key differentiating compounds that correlated with heating processes, such as 2-methylpropanal, 2-heptanone, and 2-pentylfuran, revealing the dependence of Maillard reactions and lipid oxidation behaviors on heating processes. These finding demonstrate that modulated protein structure, oxidation, lipid degradation, and the Maillard reaction, collectively impacting flavor development and HCA formation, providing a theoretical basis for safer production of grilled meat products.