Polysaccharide conjugation using

Protein-polysaccharide conjugates can also act as the stabilizers of multiple emulsions. Fechner et al. (2007) reported that, under acidic conditions, conjugate-containing water-in-oil-in-water emulsions were more stable to coalescence than the corresponding emulsions made with just sodium caseinate. They also observed that the extent of vitamin B]2 release from the inner aqueous phase of the conjugate-based system was significantly lower. This result could be useful for preparing double emulsions with variable release behaviour. 

For reasons that are probably unrelated to their technical performance, these covalent protein-polysaccharide conjugates have not yet been used commercially in food systems. But it seems that it is only a matter of time before the impressive potential of these highly functional ingredients becomes exploited on a commercial scale in various food applications — not just for emulsification, but also for foaming, gelation, waterholding, and encapsulation. 

Four different vaccines for Hib are licensed in the United States. All these vaccines are composed of Hib capsular polysaccharide conjugated to a protein carrier. All four vaccines use a different carrier. Polyribosyl ribitol phosphate (PRP) capsule is an important virulence factor that renders Hib resistant to phagocytosis by neutrophils in the absence of specific anti-capsular antibody. Antibody directed against PRP capsule of Hib is primarily responsible for host resistance to infection. The Hib vaccine is composed of the purified, capsular polysaccharide of Hib. Antibodies to this antigen correlate with protection against invasive disease. 

Different biomimetic approaches exploiting enzymatic methods using tyrosinase have been used to prepare protein-polysaccharides conjugates and to create hydrogels from biopolymers for tissue engineering application. 

Covalent protein-polysaccharide conjugates are sometimes used to avoid any flocculation and phase separation that is produced with weak non-specific protein-polysaccharide interactions. An example of such conjugates is that produced with globulin-dextran or bovine serum albumin-dextran. These conjugates produce emulsions with smaller droplets and narrower size distribution and they stabilize the emulsion against creaming and coalescence. 

Hyaluronic acid is a linear polysaccharide found in the highest concentrations in soft connective tissues where it fills an important structural role in the organization of the extracellular matrix (23,24). It has been used in ophthalmic preparations to enhance ocular absorption of timolol, a beta blocker used for the treatment of glaucoma (25), and in a viscoelastic tear formulation for conjunctivitis (26). The covalent binding of adriamycin and daunomycin to sodium hy-aluronate to produce water-soluble conjugates was recently reported (27). 

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