Stability of low density lipoprotein particles affect the formation of off-flavor in thermal egg yolk

Potassium Chloride as an Effective Alternative to Sodium Chloride in Delaying the Thermal Aggregation of Liquid Whole Egg

The potential of potassium chloride (KCl) to be used as a substitute for sodium chloride (NaCl) was studied by monitoring the effects of salt treatment on thermal behavior, aggregation kinetics, rheological properties, and protein conformational changes. The results show that the addition of KCl can improve solubility, reduce turbidity and particle size, and positively influence rheological parameters such as apparent viscosity, consistency coefficient (K value), and fluidity index (n). These changes indicate delayed thermal denaturation. In addition, KCl decreased the content of β-sheet and random coil structures and increased the content of α-helix and β-turn structures. The optimal results were obtained with 2% KCl addition, leading to an increase in Tp up to 85.09 °C. The correlation results showed that Tp was positively correlated with solubility, α-helix and β-turn but negatively correlated with ΔH, turbidity, β-sheet and random coil. Overall, compared to NaCl, 2% KCl is more effective in delaying the thermal aggregation of LWE, and these findings lay a solid theoretical foundation for the study of sodium substitutes in heat-resistant liquid egg products.

Comparison and evaluation of L. reuteri and L. rhamnosus-fermented egg yolk on the physicochemical and flavor properties of cookies

The study aims to explore an effective approach to improve the sensory quality and consumer satisfaction of cookies in the food industry. L. reuteri and L. rhamnosus were chosen to ferment egg yolk and their effects on dough properties and physicochemical properties, flavor, texture, color, and sensory acceptability of cookies were studied. Results show that the utilization of fermented egg yolk significantly decreased baking loss and increased spread factor of cookies. GC-MS analysis indicates different Lactobacillus species enhanced cookie flavor through unique mechanisms. Texture analysis shows cookies prepared with L. rhamnosus-fermented egg yolk had significantly lower hardness (1807.12 g) than control cookies (2028.34 g). Sensory evaluation reveals the L. reuteri-fermented egg yolk significantly improved the overall acceptability of cookies by enhancing appearance, flavor, and mouthfeel scores. These findings have practical implications for food manufacturers seeking to enhance their product's quality and appeal, thereby gaining a competitive edge in the market.

Effects of cholesterol removal treatment on the flavor and physicochemical properties of hot gel egg yolk

The aim of this study was to investigate effects of cholesterol removal treatment (CRT) on the flavor, taste, texture, color, and nutritional value of hot gel egg yolk (EY). The off-odor, volatile components and taste of EY treated with CRT were studied by electronic nose (E-nose), gas chromatography-mass spectrometry (GC-MS) and electronic tongue (E-tongue). The effect of CRT on the nutritional value of EY was studied by amino acid and fatty acid analysis. The CRT significantly reduced the content of hexanal, 2-amyl-furan, 1-octene-3-ol, styrene and heptanal in EY1-EY4, also decreased its bitter taste without affecting other taste and elasticity. In addition, the CRT did not affect the essential amino acids (EAA) content and L*, a* and b* values of EY1-EY4, but it led to the reduction in polyunsaturated fatty acids (PUFA) content. In general, the CRT is an effective way to reduce the off-odor of EY without affecting consumer acceptance.

Tracking transformation behavior of soluble to insoluble components in liquid egg yolk under heat treatment and the intervention effect of xylitol

The heat sensitivity of egg yolk limits its application, and xylitol can improve its thermal stability. The soluble and insoluble components of egg yolk and egg yolk containing xylitol treated at different temperatures were explored from the aspects of thermal instability behavior characterization and structure property. Magnetic resonance imaging and low field nuclear magnetic resonance showed that increased temperature induced liberation and transfer of hydrogen protons. Meanwhile, the apparent viscosity of soluble components increased, while that of insoluble components decreased. Microstructure showed that heat treatment induced aggregation and lipid transfer. SDS-PAGE showed that heat treatment induced aggregation and transformation of γ-livetin and apo-LDL. The change in crystal structure, Raman spectroscopy, and 3D fluorescence spectra showed that heat treatment resulted in the unfolding of yolk proteins, especially plasma proteins. Xylitol could alleviate transformation of components by stabilizing protein structure, alleviating the damage in protein integrity and elevation in aggregation size.

Interventional effect of compound sugar and salt on the thermal instability behavior of liquid egg yolk

In this study, the influence of compound sugar (glucose, sucrose, trehalose, and arabinose) and compound sugar and salt (glucose, sucrose, trehalose, arabinose, and NaCl) on the thermal stability of heat-treated liquid egg yolk was explored. The results showed that the addition of 4% compound sugar or 4% compound sugar salt could significantly enhance the heat resistance of liquid egg yolk and increase the denaturation temperature of liquid egg yolk to above 77°C. Moreover, the addition of sugar and salt could improve the functional properties of liquid egg yolk to varying degrees, allowing it to maintain excellent emulsification and soluble protein content after heat treatment. Further analysis using Fourier transform infrared spectroscopy showed that the increase in α-helix content in liquid egg yolk treated with sugar salt also contributes to improving the thermal stability of egg yolk. The method of inhibiting egg yolk aggregation caused by heat treatment provided in this study provides a selective method and theoretical basis for the commercial production of heat-resistant liquid egg yolk.

Quantitative Lipidome Analysis of Boiled Chicken Egg Yolk under Different Heating Intensities

The effects of the four heating intensities (hot-spring egg yolk, HEY; soft-boiled egg yolk, SEY; normal-boiled egg yolk, NEY; and over-boiled egg yolk, OEY) on lipidomes of boiled egg yolks were investigated. The results indicated that four heating intensities had no significant effect on the total abundance of lipids and lipid categories except for bile acids, lysophosphatidylinositol, and lysophosphatidylcholine. However, of all the 767 lipids quantified, the differential abundance of 190 lipids was screened among the egg yolk samples at four heating intensities. Soft-boiling and over-boiling altered the assembly structure of the lipoproteins through thermal denaturation and affected the binding of lipids and apoproteins, resulting in an increase in low-to-medium-abundance triglycerides. The decreased phospholipid and increased lysophospholipid and free fatty acid in HEY and SEY suggests potential hydrolysis of phospholipids under relatively low-intensity heating. Results provide new insights into the effect of heating on the lipid profiles of egg yolk and would support the public's choice of cooking method for egg yolks.

Changes in physicochemical properties and lipid oxidation lead to the formation of mud on salted egg yolks during storage

Salted egg yolk (SEY) becomes easily "muddy" during storage, leading to a decrease in the quality of salted eggs. The mechanism of SEY mudding was studied in this paper. The results showed that SEY hydrogen proton binding decreased, and SEY water and lipid fluidity increased during storage. In addition, the degree of lipid oxidation and monounsaturated fatty acids in salted egg yolk lipids (SEYL) increased, and primary oxidation products and secondary oxidation products were formed. Moreover, the structure of SEY was degraded to release lipids and proteins, and these proteins and lipids were re-emulsified to form new aggregates. Finally, by PLS-DA modeling analysis, it was found that the content of ω-3 polyunsaturated fatty acids and phospholipids changed significantly after SEY became muddy. These results suggest that the muddiness of SEY can primarily be attributed to higher fluidity and protein-lipid re-emulsification, and secondarily to the oxidation of SEYL.

The Quality Characteristics Formation and Control of Salted Eggs: A Review

Salted egg, a traditional characteristic processed egg product in China, is popular among consumers at home and abroad. Salted egg quality characteristics formation primarily includes the hydration of egg white, the solidification of egg yolk, the unique color and flavor of salted egg yolk, and the formation of white, fine, and tender egg whites and loose, sandy, and oily egg yolks after pickling and heating. The unique quality characteristics of salted eggs are mostly caused by the infiltration dehydration of salt, the intermolecular interaction of proteins, and the oxidation of lipids. In recent years, to solve the problems of salted eggs having high salinity, long production cycle, and short storage period, the pickling technology for salted egg has been improved and researched, which has played a significant role in promoting the scientific production of salted eggs. This paper summarizes the mechanisms of salted egg quality characteristics formation and factors influencing quality, with a perspective of providing a theoretical basis for the production of high-quality salted eggs.