Gel formation in heat-treated bovine serum albumin-kappa-carrageenan systems

Citation
S. Neiser et al., Gel formation in heat-treated bovine serum albumin-kappa-carrageenan systems, FOOD HYDROC, 14(2), 2000, pp. 95-110
Citations number
45
Categorie Soggetti
Food Science/Nutrition
Journal title
FOOD HYDROCOLLOIDS
ISSN journal
0268005X → ACNP
Volume
14
Issue
2
Year of publication
2000
Pages
95 - 110
Database
ISI
SICI code
0268-005X(200003)14:2<95:GFIHBS>2.0.ZU;2-G
Abstract
The effect of different concentrations of kappa-carrageenan on the gel stre ngth, gelation kinetics, and gel microstructure of bovine serum albumin (BS A) gels was investigated at different conditions of pH and ionic strength w ith and without the addition of potassium chloride. Two types of strengthen ing effects were observed: a major strengthening effect at the isoelectric point of BSA and slightly above, low ionic strength, and high carrageenan c oncentration (similar to 0.4-1.0% (w/v)); and a minor strengthening effect at higher pH and all ionic strengths at lower carrageenan concentration (si milar to 0.2-0.4% (w/v)). The liquid that could be removed from the gels by centrifugation had a lower carrageenan concentration than the original gel s at low pH and ionic strength, suggesting associative phase separation. Th e gelation kinetics of these gels differed from that of purr BSA or carrage enan gels, suggesting strong interactions between the polymers. At high pH or ionic strength, the gel centrifugates were enriched in carrageenan, and the gelation and melting of carrageenan could be observed in the heat denat ured BSA-kappa-carrageenan gels by dynamic oscillation measurements. These effects are explained by segregative phase separation. The results also sho w that the presence of potassium ions during the gelation of BSA is importa nt for the strengthening effect at associative conditions. This strengtheni ng effect was observed up to higher pH values when sodium ions were partly; replaced by potassium ions, and vanished completely when the potassium sal t of carrageenan was replaced by the sodium salt. This suggests that synerg istic interactions are present between the carrageenan and the BSA gel netw orks, but not between BSA and carrageenan in the sol state. (C) 2000 Elsevi er Science Ltd. All rights reserved.