Fresh egg yolk (EY) was enzymatically modified using phospholipase $A_2$ ($PLA_2$) to produce an enzymatically modified-egg yolk powder (EM-EYP). The EM-EYP offered significantly higher emulsifying activity, emulsion stability, protein solubility, and mayonnaise stability than the control EYP. By employing $PLA_2$ in the enzymatic modification process, structural changes occurred in the phospholipids and lipoproteins of the yolk, and cleavage of apo-high density lipoprotein (HDL) components (Mw 105 kDa) was detected by sodium dodecyl sulfate-polyaerylamide gel electrophoresis (SDS-PAGE). Based on its functional properties, EM-EYP has great potential as a replacement for fresh EY in the production of processed food products such as mayonnaise.