Improvement of functional properties of fish water soluble proteins with glucose-6-phosphate through the Maillard reaction

Water soluble proteins (WSP) from the flesh of blue marlin Makaira mazara were modified through the Maillard reaction with glucose (G) or glucose-6-phosphate (G6P) by heating at 60 degrees C for up to 12 h. Effects of the Maillard reaction on such functional properties of WSP as emulsifying activity, water hydration capacity, in vitro digestibility, and calcium phosphate-solubilizing property were investigated. Emulsifying activity, water hydration capacity, and digestibility were significantly improved by the phosphorylation with G6P, especially at the early stage of the Maillard reaction. On the other hand, glycosylation of WSP caused only slight improvement of these properties. Calcium phosphate-solubilizing property of WSP was increased by both glycosylation and phosphorylation, but the latter brought about more considerable improvement.