Impact of urea on the three-dimensional structure, viscoelastic and thermal behavior of iota-carrageenan

Abstract

Urea breaks hydrogen bonds among biopolymers leading to structural destabilization. In the case of hydrocolloids urea addition is thought to impact gelation. Detailed information about its pertinent role on influencing the structure-function relationships of hydrocolloids is still elusive, however. The present investigation is aimed at delineating hydrocolloids structural behavior in the presence of urea employing iota-carrageenan as a model system. X-ray fiber diffraction, rheological and thermal properties of two iota-carrageenan solutions with weight concentrations 4.5 and 6.0% w/w at two urea molar concentrations (0.5 and 2.0 M) with and without heat treatments have been analyzed. X-ray results suggest that the canonical double helical structural arrangement of iota-carrageenan is maintained even after urea addition. However, improved crystallinity, ordering and altered unit cell dimensions especially with heat treatments of the binary mixtures indicate the promotion of favorable interactions among carrageenan helices in the presence of urea. Increased elastic modulus and onset temperature of melting endotherm with the heat treatment compared to cold addition further attests the X-ray observations of enhanced structural ordering. Overall, results suggest that urea molecules synergistically aid iota-carrageenan interactions and stabilize structure of junction zones. Our findings are deemed to be helpful in the design and development of novel non-food applications of hydrocolloids.

Effect of a novel environmentally friendly additive of polyaspartic acid on the properties of urea formaldehyde resins/montmorillonite

“…Urea‐formaldehyde (UF) resin is a polymeric condensation product synthesized by formaldehyde and urea, and it is considered as one of the most important wood adhesives. In the past decades, because of their low costs, nonflammability, high curing rate, and the light color, UF resins are used in vast amounts and as the most important adhesive by far in the production of wood based panels, such as medium density fiberboard or others . However, UF resins also show some disadvantages, such as low viscosity, low heat‐stability, and, most importantly, the emission of free formaldehyde .…”

The Principle of Polysaccharide Gels

“…ι-Carrageenan is a more highly sulfated galactan and is also most characterized polysaccharide [59]- [65]. The polymer consist of O-3-linked β-D-galactopyranosyl 4-sulfate and O-4-linked 3,6-anhydro-α-D-galactopyranosyl 2-sulfate residues ( Figure 1).…”

Structural Elucidation, Modification, and Structure-Activity Relationship of Polysaccharides in Chinese Herbs: A Review

“…Compared with the primary structure, advanced structure of polysaccharides is more likely to affect their functions ( 46 , 47 ). Three-dimensional network structures of polysaccharide molecules are easily formed via van der Waals forces, hydrogen bonds, and covalent bonds.…”