Vb. Galazka et al., Emulsifying properties of ovalbumin in mixtures with sulphated polysaccharides: effects of pH, ionic strength, heat and high-pressure treatment, J SCI FOOD, 80(8), 2000, pp. 1219-1229
The influence of sulphated polysaccharides (dextran sulphate (DS), i-cafiag
eenan (i-CAR) and kappa-carrageenan (kappa-CAR)) on the emulsifying propert
ies of ovalbumin (OVA) has been investigated over a range of pressures and
temperatures. Oil-in-water emulsions (10gl(-1) protein, 200ml(-1) n-tetrade
cane, pH 6.2) prepared with heat-treated (80 degrees C for 10min) mixtures
of OVA + DS (1:0.25 by weight) had increased creaming stability but unchang
ed average droplet size compared to those made with untreated OVA and OVA DS. Emulsions made with pressure-processed (600MPa for 20min) OVA + DS (1:
0.25 or 1:0.5 by weight) mixtures had the best emulsifying efficiency and s
tability. Under similar experimental conditions, replacement of DS with eit
her i- or kappa-CAR gave emulsions with larger droplets and more rapid seru
m separation, probably owing to depletion flocculation. High-pressure treat
ment (600 MPa) of the OVA and mixed biopolymer solutions at pH 6.2 in the p
resence of salt (>0.04M) led to unstable emulsions, and so the protective e
ffect of DS was lost. High-pressure treatment (600MPa) of emulsions prepare
d with native OVA or OVA + DS mixtures induced significant levels of floccu
lation, as indicated by changes in the average droplet size and creaming be
haviour. (C) 2000 Society of Chemical Industry.