Abstract:
Egg liquid products were important raw materials in food processing and were widely used in baking, meat products, pasta products and other fields. To investigate the effects of NaCl on the functional and physicochemical properties of compounded egg liquids with different egg white-yolk ratios, this study determined the changes in gel properties and foaming properties at different NaCl concentrations (0, 0.5%, 1.0%, 1.5%). These changes were further analyzed in combination with zeta potential, particle size, Fourier-transform infrared spectroscopy, endogenous fluorescence spectroscopy, ultraviolet spectroscopy, and free sulfhydryl content to elucidate the underlying mechanisms. The results showed that NaCl affected the gel properties of the compounded egg liquid, and the gel hardness, elasticity and chewiness increased with the increase of NaCl addition when containing egg yolks, with the best at 1.0%. The foaming ability firstly increased and then decreased, with a variation range of 1.5%~4.0%. When the proportion of egg yolk was low, NaCl had no significant effect on the viscosity. When the proportion of egg yolk was high, the viscosity increased with the concentration of NaCl. NaCl decreased the absolute value of zeta potential, increased the particle size, and a small amount of aggregation occurred. The peak intensity of infrared spectra varied, and the infrared absorption at 1700~1600 cm
−1 was enhanced. The fluorescence intensity decreased with the increase of NaCl addition at 30% of yolk. At 70% of yolk, the fluorescence intensity increased at 0.5% and 1.0% NaCl addition, and decreased at 1.5%. The rest of the samples showed no pattern. The intensity of absorption peaks in UV spectra increased. NaCl decreased the free sulfhydryl content of compound egg solution with 30% and 70% of yolk proportion, but there was no regularity. The changes of free sulfhydryl content of egg white liquid, egg yolk liquid and egg yolk proportion of 50% of compound egg solution were complicated. In conclusion, the addition of 1.0% NaCl had a certain improvement effect on the functional properties of the compounded egg liquids, and this study can provide guidance for the development and practical application of high-quality compounded egg liquids.