Effects of the length of polysaccharide chains on the functional properties of the Maillard-type lysozyme-polysaccharide conjugate

The effect of the length of polysaccharide chains on the functional properties of Maillard-type protein-polysaccharide conjugates was investigated using the lysozyme as a model protein, various sizes of galactomannan as a polysaccharide, and xyloglucan as an oligosaccharide. The emulsifying properties of the lysozyme-galactomannan conjugates increased in proportion to the length of polysaccharide chains. On the other hand, the heat stability of the lysozyme-galactomannan conjugates greatly increased in the range of 3.5-24 kDa galactomannan, regardless of its molecular mass. In addition, the effects of the binding number of polysaccharide to lysozyme on the emulsifying properties of the lysozyme-galactomannan conjugates were further investigated using 1 and 2 mol of the galactomannan (24 kDa)-attached lysozyme. The 2 mol of the polysaccharide-attached lysozyme showed better emulsifying properties than 1 mol of the polysaccharide-attached protein. The residue most sensitive to the Maillard reaction in a lysozyme was identified as the 97-lysine using the lysozyme-xyloglucan conjugate.