Application of Pre-soaking with Ethanol and Acetic Acid in Salted Duck Egg Desalination

Abstract

Salted duck egg, as a traditional egg product, are very popular in China. However, its high contents of NaCl brings health hazard. In this work, the influence of successive presoaking with 0.01% acetic acid and 0.35% ethanol and desalination soaking on the water content, salt content, oil yield, maturity, sensory quality and eggshell membrane microstructure of salted duck eggs were explored using atomic absorption spectrometry, chromatic meter, texture analyzer, scanning electron microscope (SEM) and sensory evaluation. For pre-soaking samples, the redness and brightness of the yolk changed to 16.10 and 67.54 after 12-day salinization at 37 ℃, respectively, and the yolk index has reached 95%, suggesting that pre-soaking samples get salted after 12 days, while the control group needed 21 days to get ripe. The salt content of egg protein in the pre-soaking group was assayed to be 1.02% on the 6th day of desalting, which was 18% less than that in the control group, while the oil yield and the hardness of the pre-soaking group reached 50.82% and 2 604. 33 g. The appearance, smell, color, taste and other sensory indicators of the pre-soaking samples were similar to those of the control group, while the control group tasted much more salt. The microstructure observation of eggshell membrane showed that pre-soaking enlarged the space between inner membrane fibers, which improved the two-way permission of water and sodium chloride molecules, resulting in rapid salinization and desalting of pre-soaking samples.

Keywords

• salted duck eggs
• pre-soaking
• desalination
• eggshell membrane
• scanning electron microscope