FUNCTIONAL PROPERTIES OF ALFALFA LEAF PROTEIN: FOAMING

Alfalfa leaf proteins extracted with sodium chloride (1M), sodium hydroxide (0.05M) or Tris buffer (0.1M) had poor foaming properties compared to proteins obtained by direct expression of leaf juice. Extraction of lipids from all protein extracts markedly improved both foam formation and foam stability. Foam expansion of alfalfa leaf protein surpassed that of ovalbumin but the foam was less stable. The pH foam expansion profile resembled the solubility pattern of this protein. The delipidated protein preparations showed little pH effect being rather constant between pH 2–10. Foam stability of all preparations was markedly pH dependent showing minima in the isoelectric range around pH 3.5. Both sucrose and sodium chloride reduced the foaming of leaf proteins.