Changes in Yolk States of Duck Egg during Long-Term Brining

Abstract

To elucidate the relationship between shyandan yolk formation and NaCl penetration degree, fresh duck eggs were brined in 26% NaCl and a prolonged brining test was conducted for up to 24 weeks. Shyandan yolk was obtained from brine-cured duck shell eggs in 26% NaCl for 4-6 weeks and subsequently heated at 85 degrees C for 90 min. Though NaCl contents for albumen and yolk increased to 14.8 and 8.9%, respectively, during the prolonged test for up to 24 weeks, the R values (NaCl/water x 100) were similar (increased from 0.6 to 21) throughout the brining process. The oil-off ratio of the yolk increased rapidly from 14 to 50% (0-6 weeks) and gradually decreased during the extended brining. Granulation and gelation of yolk appeared in the different stages of the brining process. This study demonstrates that the formation of shyandan yolk was determined by the degree of NaCl penetration.

Effect of salting processes on chemical composition, textural properties and microstructure of duck egg

“…Oil exudation was measured according to the method of Lai et al 2 with slight modification. Yolk (3 g) was homogenized with 35 mL n-hexane/2-propanol (3 : 2, v/v) at 5000 rpm for 10 min using a homogenizer (Polytron, PT 2100, Kinematica AG, Lucerne, Switzerland).…”

“…Generally, salted egg can be made by brining eggs in saturated saline or by coating the egg with soil paste mixed with salt for about 15-30 days. 1,2 The immersing method is faster and more convenient for production of salted egg. 3 In addition to being consumed as the whole egg, salted egg yolks are widely used as a filling in some Chinese sweets such as moon cakes and other desserts.…”

The Influence of Liquid Smoke on the Chemical Characteristics of Salted Egg

“…Oil exudation was determined according to the method of Lai et al (1997;1999; with slight modification. Oil exudation was defined as the proportion of free to total lipid content.…”

A simple method to evaluate oil in salted egg

“…[1] Salted eggs are produced by brining eggs in saturated saline (immersing method) or by coating eggs with soil paste mixed with salt (coating method) for 20-45 days. [2,3] During salting, the yolk gradually solidifies and hardens, whereas the albumen loses its viscosity and becomes watery. [1,4] Consumers love salted egg mainly for its yolk.…”

“…[1] Oil exudation in yolk increases with time resulting from dehydration and protein denaturation. [3,4] The oil exuded from YSE exists in the form of free lipids, which are released from lipoprotein. The free lipids on the interface of granulated yolk spheres provide the gritty texture of cooked salted egg yolk.…”