Improvement of egg yolk powder properties through enzymatic hydrolysis and subcritical fluid extraction

Egg yolk powder is a widely used functional food ingredient due to its beneficial physicochemical and nutritional properties. However, its utilization in food can be limited due to its relatively high lipid content and low watersolubility. To address this issue, a two-step processing method utilizing enzymatic treatment combined with subcritical fluid extraction was investigated in this study. This method effectively reduced lipid content and improved water-solubility of egg yolk powder. An alcalase enzyme concentration of 500 U/g, extraction temperature of 313.15 K, extraction time of 120 min and a solid-liquid ratio of 1:9 (g:mL) produced powder with 20% lipid content and 71% water-solubility. Enzymatic hydrolysis clearly enhanced subcritical fluid extraction efficiency. This was attributed to hydrolysis disrupting the structure of egg yolk particles and facilitating the release of enclosed lipid molecules and was confirmed by scanning electron microscopy and laser confocal microscopy.