Foaming Property of Hydrolysis Products of Keratin. V.

Foaming Property of High Molecular Weight Components Fractionated from Keratin Hydrolysate by Membrane Ultrafiltration and the Effect of Addition of Metal Salts

Abstract

Forming components were fractionated from a keratin hydrolysate with a molecular weight (F.M.W.) in the range of about 50, 000 by membrane ultrafiltration. Foam heights and stabilties of the fractions were measured. Ferrous salt FeSO₄·7H₂O or calcium salt CaCl₂·2H₂O was added at various concentrations to aqueous solutions of the keratin hydrolysate fractions.
The effects of added iron (II) or calcium on foam heigthts and stabilities and the amounts of sediment were studied. The maximum concentration of added iron (II) which could not form a precipitate was also determined.
The foam heights and stabilities of the keratin hydrolysate of the present F.M.W. and its fractions increased with the addition of iron (II) or calcium.
Based on foam heights, foam stabilities, formation of Fe (II)-hydrolyzed protein chelate and the amounts of precipitate and sediment formed by addition of iron (II) or calcium, the upper limit of molecular weight of keratin hydrolysate for use in a protein foam extinguisher was determined as 300, 000.