Effects of salting treatment on the physicochemical properties, textural properties, and microstructures of duck eggs

Abstract

In order to illuminate the forming process of salted egg, the effects of the brine solution with different salt concentrations on the physicochemical properties, textural properties, and microstructures of duck eggs were evaluated using conventional physicochemical property determination methods. The results showed that the moisture contents of both the raw and cooked egg whites and egg yolks, the springiness of the raw egg yolks and cooked egg whites exhibited a decreasing trend with the increase in the salting time and salt concentration. The salt content, oil exudation and the hardness of the raw egg yolks showed a constantly increasing trend. Viscosity of the raw egg whites showed an overall trend in which it first deceased and then increased and decreased again, which was similar to the trend of the hardness of the cooked egg whites and egg yolks. As the salting proceeded, the pH value of the raw and cooked egg whites declined remarkably and then declined slowly, whereas the pH of the raw and cooked egg yolks did not show any noticeable changes. The effect of salting on the pH value varied significantly with the salt concentration in the brine solution. Scanning electron microscopy (SEM) revealed that salted yolks consist of spherical granules and embedded flattened porosities. It was concluded that the treatment of salt induces solidification of yolk, accompanied with higher oil exudation and the development of a gritty texture. Different salt concentrations show certain differences.

Physicochemical and techno‐functional properties of acid‐aided pH‐shifted protein isolate from over‐salted duck egg (Anas platyrhucus) albumen

“…Generally, ovomucin is a highly polymerised large molecule protein that is considered to be a key protein in the maintenance of the albumen viscosity (Omana et al , ). Ovomucin can bind to electrolytes and is very sensitive to salts (Xu et al , ). Xu et al () also reported that the viscosity of the duck egg albumen showed an overall decreasing trend after salting.…”

“…Salted duck eggs are popular traditional preserved food product in China and South‐East Asian countries due to its unique flavour, texture and taste (Xu et al , ). Normally in Thailand, fresh eggs of duck were salted by coating with a paste of mud and salt (4:1 w/w), covering with rice hull ash and storing at room temperature.…”

“…With further salting for ≥ 30 days, over‐salted eggs with salt content higher than 5% were obtained (Chaijan & Panpipat, ). Only coagulated salted yolk can be sold for some bakery products (Xu et al , ; Chaijan & Panpipat, ). The over‐salted albumen (egg white) is usually discarded because of its heavy salty taste (Chaijan & Panpipat, ).…”

“…Venkatachalam () noted that the yield stress which used as an important indicator of foam capacity increased from 32.33% to 70.55% due to duck egg salting. The textural characteristic of cooked salted egg albumen was correspondence to its viscosity which was governed by salting time and salt concentration (Xu et al , ). Therefore, the processing parameters can cause either negative or positive effect on physicochemical properties and functionalities of albumen proteins.…”

Effect of hydroxyl radical-induced oxidation on the structure and heat-induced gel properties of ovalbumin

“…As oxidation progressed, the viscosity of the Ox‐OVA aqueous solution decreased with the oxidation time. This indicated that the intermolecular interaction of OVA was weakened after oxidation by hydroxyl radicals (Sheng et al, ; Xu et al, ).…”