abstract
Pound cake is made from equal portions of egg, wheat flour, sugar and margarine or butter. Its quality is
codetermined by the protein network formed during baking. A key insight on egg yolk functionality is
that during batter mixing the yolk granules disintegrate and dissolve most of their protein into the batter
liquor. This was demonstrated by comparing the protein population of a reference batter liquor with that
in batter liquor of which the added yolk was pretreated to disintegrate the granules. Using a 15N-labeling
approach, the protein network formation was monitored during cake baking in an electrical resistance
oven. Protein was extracted in different media, i.e. diluted saline, aqueous ethanol, a buffer containing
sodium dodecyl sulfate and one containing dithiothreitol, and analyzed by size-exclusion HPLC. Both egg
yolk plasma and granule proteins are incorporated in the protein network by disulfide crosslinking
during pound cake baking. Only phosvitin, which lacks both free sulfhydryl and intermolecular disulfide
bonds, does not take part in the protein network via disulfide bridge formation