Structure and functional performance of gigartinacean kappa-iota hybrid carrageenan and solieriacean kappa-iota carrageenan blends

Hybrids of kappa and iota carrageenans, known as kappa-2 carrageenans, of contrasting phycological origin and type of hybridization were compared chemically and functionally. Nuclear magnetic resonance spectrometry showed gigartinacean kappa-2 (hybridization was known to be a co-occurrence of kappa and iota structures in a chain) to contain 45% iota and 55% kappa, very similar to a 3:3 kappa:iota hand-made blend of solieriacean origin (hybridization was that kappa and iota occurring as separate chains). Gel permeation chromatographic data, however, demonstrated the gigartinacean extract to possess lower molecular weight compared to the solieriacean extracts, a hint to the variability in the origin of the two hybrid carrageenans. As texturing agents in water and milk systems, gigartinacean kappa-2 was found to produce inferior gels compared to its hand-made counterpart. However, both hybrids were found to exhibit similar functional performance as viscosity-enhancing/stabilizing agent in hot-processed chocolate milk preparations, and analogous inutility as viscosity build-up agent in cold-processed chocolate milk. A hand-made solieriacean kappa-iota blend can have the same properties as a gigartinacean kappa-2, but it depends on the actual application which blend performs comparable to kappa-2. (C) 2003 Elsevier Ltd. All rights reserved.