COMBINED EFFECTS OF SPRAY DRYING AND ENZYMATIC TREATMENT ON THE TECHNO-FUNCTIONAL PROPERTIES OF DRIED EGG YOLK MAIN FRACTIONS

摘要

Changes in the techno-functional properties of hen’s egg yolk main fractions,granules and plasma,were studied under various spray drying conditions and enzymatic modification via phospholipase A2 (PLA2).The functional properties,e.g.rheological behavior,of plasma were maintained in a more or less native status if an enzymatic modification was done before spray drying.Furthermore,a PLA2 pre-processing improved significantly the surface activity of dried plasma.Without enzymatic treatment spray dried plasma showed an intense loss of surface activity and gelling properties due to a heat induced denaturation and aggregation of plasma- livetins and LDL-apoproteins.In contrast,high air inlet and outlet temperatures during spray drying resulted in a significant increase in surface activity of reconstituted granules.This phenomenon could be enforced by an enzymatic pre-processing.PLA2 modified granules showed a considerable improved solubility and surface activity after spray drying compared to untreated dried granules.