Emulsifying properties of ovalbumin in mixtures with sulphated polysaccharides: effects of pH, ionic strength, heat and high-pressure treatment
✍ Scribed by Vanda B Galazka; Eric Dickinson; Dave A Ledward
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 216 KB
- Volume
- 80
- Category
- Article
- ISSN
- 0022-5142
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✦ Synopsis
The in¯uence of sulphated polysaccharides (dextran sulphate (DS), i-carrageenan (i-CAR) and k-carrageenan (k-CAR)) on the emulsifying properties of ovalbumin (OVA) has been investigated over a range of pressures and temperatures. Oil-in-water emulsions (10 g l À1 protein, 200 ml l À1 ntetradecane, pH 6.2) prepared with heat-treated (80 °C for 10 min) mixtures of OVA DS (1:0.25 by weight) had increased creaming stability but unchanged average droplet size compared to those made with untreated OVA and OVA DS. Emulsions made with pressure-processed (600 MPa for 20 min) OVA DS (1:0.25 or 1:0.5 by weight) mixtures had the best emulsifying ef®ciency and stability. Under similar experimental conditions, replacement of DS with either ior k-CAR gave emulsions with larger droplets and more rapid serum separation, probably owing to depletion ¯occulation. Highpressure treatment (600 MPa) of the OVA and mixed biopolymer solutions at pH 6.2 in the presence of salt (b0.04 M) led to unstable emulsions, and so the protective effect of DS was lost. High-pressure treatment (600 MPa) of emulsions prepared with native OVA or OVA DS mixtures induced sig-ni®cant levels of ¯occulation, as indicated by changes in the average droplet size and creaming behaviour.