Vb. Galazka et al., Influence of high pressure on interactions of 11S globulin Vicia faba withiota-carrageenan in bulk solution and at interfaces, FOOD HYDROC, 14(6), 2000, pp. 551-560
The influence of L-carrageenan (L-CAR) on the solution, interfacial and emu
lsifying properties of 11S globulin Vicia faba at low ionic strength and pH
8 has been investigated before and after high-pressure processing at 200 M
Pa for 70 min. The total calorimetric enthalpy (DeltaH) and size exclusion
chromatography studies for the: pure 11S indicate that there is subunit dis
sociation and extensive aggregation of the protein during or following trea
tment. Under the same treatment conditions, 1-anilinonaphthalene-8-sulphona
te (ANS) data has shown increased protein surface hydrophobicity. Pressure
treatment of 11S gives much lower values of the surface tension, and appare
nt surface shear rheology experiments show that the molecules in the film a
dsorbed from the pressurised 11S are much more strongly interacting than th
ose adsorbed from the native 11S. However, emulsions prepared with pressure
processed 11S give substantially bigger droplets than those made with the
untreated pure protein. Addition of iota -CAR to 11S reduces the denaturati
on temperature (T-m), the DeltaH value, and protein surface hydrophobicity.
Size exclusion chromatography at low ionic Strength is indicative of compl
ex formation. Tension measurements at the air-water interface are also cons
istent with the presence of a complex. Emulsions made with the simple 1:0.3
3 mixture of 11S + iota -CAR give emulsions with smaller droplets and press
ure processing of the biopolymer mixture leads to emulsions with even small
er droplets. The presence of iota -CAR at low ionic strength appears to pro
tect the globulin against pressure-induced aggregation. (C) 2000 Elsevier S
cience Ltd. All rights reserved.