Evaluation of protein structural changes and water mobility in chicken liver paste batters prepared with plant oil substituting pork back-fat combined with pre-emulsification

• Pre-emulsifying back-fat and plant oil increased water- and fat-binding of liver paste batters.
• Pre-emulsification and substituting above 20% back-fat decreased T21a, T21b and T22.
• Added 20–40% plant oil combined with pre-emulsification decreased α-helix content.
• Pre-emulsification and plant oil substitution changed Trp and Tyr hydrophobic residues.

Protein structural changes and water mobility properties in chicken liver paste batters prepared with plant oil (sunflower and canola oil combinations) substituting 0–40% pork back-fat combined with pre-emulsification were studied by Raman spectroscopy and low-field nuclear magnetic resonance (NMR). Results showed that pre-emulsifying back-fat and plant oil, including substituting higher than 20% back-fat with plant oil increased the water- and fat-binding (p < 0.05) properties, formed more even and fine microstructures, and gradually decreased the NMR relaxation times (T21a, T21b and T22), which was related to the lower fluid losses in chicken liver paste batters. Raman spectroscopy revealed that compared with a control, there was a decrease (p < 0.05) in α-helix content accompanied by an increase (p < 0.05) in β-sheet structure when substituting 20–40% back-fat with plant oil combined with pre-emulsification. Pre-emulsification and plant oil substitution changed tryptophan and tyrosine doublet hydrophobic residues in chicken liver paste batters.