Abstract: Transglutaminase (TGase) can effectively improve the properties of proteins through cross-linking, therefore improves the properties of foods. Egg yolk powder was obtained by spray drying with different amounts of TGase in egg yolk. The emulsifying and gelling properties of egg yolk powder were studied. The secondary structure of protein in egg yolk powder was determined by Fourier transform infrared spectroscopy (FTIR) technique to analyze the influence of enzymes on the emulsifying properties of yolk powder. The effect of TGase on the gelling function of egg yolk powder was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE)electrophoresis and determination of superficial thiol number. The results showed that with the addition of TGase, the gelling of egg yolk powder initially increased and then decreased. The gelling was maximized when the additive amount of TGase was 1.5 U/g egg yolk. According to superficial thiol number analysis, the cross-linking effect of TGase could change the superficial thiol number, hence change the gelling network state, so that the water holding capacity of the egg yolk powder was changed and its gelling properties improved,. The emulsification activity index (EAI) of egg yolk powder first increased and then decreased with the additive amount of TGase, and the highest EAI was obtained with 2.0 U/g TGase. According to FTIR, the α-helix changed to β-sheet, with the same trend as EAI. The emulsion stability index (ESI) of egg yolk powder first decreased and then increased with the additive amount of TGase, and the lowest ESI was obtained with 2.0 U/g TGase.
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