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In this study, the method of subcritical fluid-propane extraction (SPE) used to coproduce egg yolk oil (EYO) and low-fat egg yolk powder from spray-dried egg yolk powder (EYP) was investigated. Results showed that the optimum parameters were: extraction temperature of 313.15 K, extraction time of 120 min, and solid-liquid ratio of 1:9 (g/mL). Under this condition, the residual oil rate of EYP was 21.04%, which was much lower than that of ethanol extraction (39.24%). Scanning electron microscopy reveled that serious disruptions of egg yolk sphere extracted by SPE were observed, facilitating the EYO extraction. In addition, oil extracted by SPE had lower acid value and peroxide value than that of ethanol extraction. Moreover, the emulsifying properties and solubility of low-fat EYP obtained by SPE were similar to the original egg yolk powder. This study provides a new technique for coproducing high-quality oil and protein. Image 1 • SPE was used to coproduce yolk oil and low-fat dried egg yolk powder. • Yolk sphere was severely damaged and released more lipids under SPE. • Compared to ethanol extraction, EYO extracted by SPE had better oil quality. • The emulsifying properties and solubility of LYP-P were similar to OYP. [ABSTRACT FROM AUTHOR]

Egg yolk will undergo gelation when it is stored below −6 °C due to protein denaturation and aggregation. In this study, the cryoprotective effects of sugar alcohols with various molecular weights (erythritol, xylitol, mannitol and maltitol) on egg yolks stored at −18 °C were compared, and the corresponding mechanism was elucidated. The rheological and textural properties showed that small molecular weight sugar alcohol could greatly increase the fluidity of frozen-thawed yolk and weaken the gel strength. Smaller molecule sugar alcohol, such as erythritol, had better efficiency in inhibiting the aggregation of proteins during freezing, due to the restricted growth of ice crystals, which was verified by the decrease in the loss of immobile water and crystallization enthalpy. In addition, the dominant interaction between protein molecules changed from hydrophobic interactions to electrostatic interactions in the presence of erythritol. It could be concluded that, small molecule sugar alcohols especially erythritol could more effectively protect proteins from aggregation by inhibiting the denaturation caused by ice crystal growth and hindering intermolecular hydrophobic interactions. • Small molecule sugar alcohol can effectively improve fluidity of frozen egg yolk. • The improved fluidity of frozen egg yolk was related to the reduced aggregation and ice crystal formation. • Erythritol addition could restrict inter-molecular hydrophobic interaction between frozen egg yolk proteins. • The gelation and emulsifying properties of frozen egg yolk were significantly improved. [ABSTRACT FROM AUTHOR]

Spray-dried egg white powder (EWP) is limited to be used as the raw material in beverage industry due to its poor dispersibility. In this work, a new method that combined heating and enzymatic hydrolysis was proposed to resolve this problem. Appropriate heating treatment could obviously increase the dispersibility of EWP by increasing its particle size, whereas enzymatic hydrolysis could degrade the thermolabile proteins and release the highly negative polypeptides, thus increasing the stability of EWP in water. The highest coefficient of stability (COS) was achieved when the amount of enzyme addition was 0.03% with 75 °C heat treatment (75 + 0.03). Also in this condition, many concave holes on the surface of EWP (75 + 0.03) can be observed, which was beneficial to the wettability. These results indicate that the heat and enzymatic treatment have a synergistic effect in improving the dispersibility and thermostability of EWP. • Heat and protease together improved the dispersibility of egg white powder (EWP). • The dispersion rate of EWP was enhanced by heat-induced aggregation of proteins. • The dispersion stability of EWP positively correlated with net charge. [ABSTRACT FROM AUTHOR]

Abstract Egg gel is the combined gelation of egg white (EW) and egg yolk (EY); its properties depend on the fixed ratio of EW and EY in shell egg. This study investigated the gelation properties of egg mixtures in artificial blends to explore innovative egg solutions catering to the market demands and provide guidance for the production of creative egg products. Results showed that solubility of samples decreased with the increase of EY proportion while solid content increased. More surface hydrophobicity and total SH group increases were observed with higher EY proportion. Rheological tests suggested that adding EY decreased samples' initial G' values. Egg gel containing 20% EY presented the largest hardness value, which seems to be related to the fine gel network microstructure. Besides, the springiness and water-holding capacity of gels gradually increased with EY addition, which may be the result of dense microstructure and high solid content of EY. Highlights • Gelling properties of egg white and yolk were dependent on the proteins. • Water-holding capacity of egg gels was closely related to gels' microstructure. • Yolk filled the cavities existing in egg white gels, making microstructure denser. [ABSTRACT FROM AUTHOR]

The deterioration of foaming performance of spray-dried egg white powder (EWP) dramatically affects its application in aerated foods. This study compared the effects of spray drying at different outlet temperatures (70, 80 and 90 °C) and freeze drying on the foaming properties of EWP. The results showed that the foaming capacity/foam stability of reconstituted EW solutions prepared by spray-dried EWP significantly decreased with the increase of outlet temperatures and was far smaller than freeze-dried ones. Correlation analysis results showed that the foaming performance of spray-dried EWP was highly correlated with the particle size, surface tension and interface adsorption behavior. The understanding of drying effect on their foam properties could assist in selecting the appropriate drying methods and measures to optimize the utilization of EWP in the food industry. • The foaming performance of egg white powder decreased at high drying temperature. • Drying induced protein aggregation slowed down its interfacial adsorption capacity. • The surface tension and viscosity of egg white dominate its foaming performance. [ABSTRACT FROM AUTHOR]