Tannic acid-induced changes in water distribution and protein structural properties of bacon during the curing process

The changes in water distribution and structural properties of myofibrillar protein (MP) in marinated pork belly induced by the addition of different concentrations (0.00, 0.25, 0.50, 1.00, and 2.00 g/kg) of tannic acid (TA) were examined. Transverse relaxation time and population measurements revealed that the 0.50 g/kg TA treatment improved water retention in the marinated pork belly samples. There was an initial increase and a subsequent decrease in the free amino group, α-helix, and β-sheet content, as well as fluorescence intensity, as TA concentration increased. Meanwhile, the opposite trend was observed in the dityrosine content and surface hydrophobicity of the marinated pork belly samples. The free amino group, α-helix content and fluorescence intensity of 0.50 g/kg TA samples were increased by 23.1%, 10.3% and 28.6%, and dityrosine content and surface hydrophobicity were decreased by 2.6% and 2.9% compared with the samples without TA. Therefore, the effect of TA on water distribution and protein structural properties in marinated pork belly is related to its concentration. Addition of 0.50 g/kg TA can significantly delay the loss of water and improve protein structure stability of MP in pork belly during marinating.