Recent advances in the understanding of heat set gelling polysaccharides

β-Glucans

β-Glucans occur widely in plants, fungi and bacteria as structural components. The current chapter focused on β-glucans from cereals, mushrooms and some microorganism-produced β-glucans, such as curdlan, in terms of their sources, structural features, conformational and physicochemical properties, bioactivity and related health benefits. The effects of structure, molecular weight and conformation on the functionality of these β-glucans were discussed and their structure–function relationships were elucidated.

Hydrocolloids as thickening and gelling agents in food: a critical review

Hydrocolloids are widely used in many food formulations to improve quality attributes and shelf-life. The two main uses are as thickening and gelling agents. As thickening agents, they find uses in soups, gravies, salad dressings, sauces and toppings while as gelling agents, they are extensively used in products like jam, jelly, marmalade, restructured foods and low sugar/calorie gels. The role of specific hydrocolloids for thickening and for gel formation is reviewed pinpointing specific applications in food formulations and for product development.

Voltammetric Characterization on the Hydrophobic Interaction in Polysaccharide Hydrogels

Cyclic voltammetric (CV) investigations on the properties of microdomains in polysaccharide hydrogels, methyl cellulose (MC) and kappa-carrageenan (CAR), coated on glassy carbon electrodes were reported in which methylene blue (MB), tris(1,10-phenanthroline)cobalt(III) (Co(phen)3(3+/2+)) cations, and ferricyanide/ferrocyanide (Fe(CN)6(3-/4-)) anions were used as electroactive probes. Information on the patterns and strength of intermolecular interactions in these polysaccharide hydrogels can be inferred from the net shift of normal potentials (E degrees'), the change of peak currents (ip), the ratio of binding constants (K(red)/K(ox)) for reduced and oxidized forms of bound species, and the apparent diffusion coefficients (D(app)) of probe in hydrogels. The transition of hydrophobic interaction in MC hydrogel with temperature was manifested by the CV method, which is in agreement with the evolution of the storage modulus (G') during gelation. It was also found that, in addition to inducing the change of E degrees' and ip of these probes used, the hydrophobic-hydrophilic nature of the microenvironment in hydrogels coated on the substrate electrodes greatly influenced the peak-peak separation (DeltaEp) of MB and the redox reversibility of Fe(CN)6(3-/4-) via modulation of both the heterogeneous electron-transfer process at the gel-substrate interface and the charge-transfer process in hydrogels. The results imply that the CV method is of significant benefit to the understanding of the gelation driving forces in the polysaccharide hydrogels at a molecular level.

Protein/Polysaccharide Cogel Formation Based on Gelatin and Chemically Modified Schizophyllan

In the work, aldehyde groups were quantitatively introduced into schizophyllan (SPG) side chains through periodate oxidation. The periodate-oxidized SPG (POSPG) forms an elastic gel with gelatin. The cogel formation is based on the Schiff-base reaction between the amino groups of gelatin chains and the aldehyde groups of POSPG chains. The POSPG/gelatin cogel has an elastomeric character with a very small value of loss tangent. The gelation kinetics and gel properties were discussed as a function of POSPG concentration, gelatin concentration, oxidation degree, temperature, and pH. This method can be used to design a large variety of cogels between SPG and proteins.