Abstract:The byproduct of yolk immunoglobulin, freeze-thaw egg yolk pellet (FYP), was used as raw material to prepare low-fat egg yolk powder and egg yolk oil with desirable functional properties and quality through enzymatic hydrolysis and subcritical extraction, aiming to realize the comprehensive utilization of egg yolk resources. Initially, denatured FYP was subjected to enzymatic hydrolysis with alcalase, and the improvement of functional properties were investigated. Subsequently, subcritical extraction was employed to obtain low-fat egg yolk powder and the byproduct(egg yolk oil). The extraction process was optimized primarily based on the residual oil rate of low-fat egg yolk powder. Propane was selected as the extraction solvent, and the optimal extraction conditions were determined to be at extraction temperature of 35 ℃, pressure of 1.5 MPa, extraction time of 120 minutes, and solid-to-liquid ratio of 1 g∶7 mL. Furthermore, the solubility and emulsification of low-fat egg yolk powder were analyzed. The results demonstrated that the solubility and emulsifying capacity of low-fat egg yolk powder increased with an increase in enzyme dosage, while the residual oil rate decreased significantly. At the enzyme dosage of 1 000 U/g, the residual oil rate of the low-fat egg yolk powder reached 15.50%. However, further increasing the enzyme dosage led to a decrease in oil extraction efficiency. Therefore, the optimal enzyme dosage was determined to be 1 000 U/g, where the low-fat egg yolk powder has reduced fat content and desirable solubility and emulsifying properties.
