Subcritical fluid extraction treatment on egg yolk: Product characterization

Abstract 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.