Cooperative effect of relative humidity and glucose concentration on improved solubility of shellfish muscle protein by the Maillard reaction

Abstract

Myofibrillar protein (Mf) of scallop muscle was reacted with various concentrations of glucose at 50°C and different relative humidities (RH 5-95%), and the change in solubility of Mf in low- and high-ionic-strength media was investigated. When the lyophilized Mf-glucose mixture (Mf:glucose = 1:18) was reacted at RH 5% and RH 35%, the solubility of Mf in 0.1 M NaCl increased markedly and almost equaled the solubility in 0.5 M NaCl. However, the improvement of the solubility in 0.1 M NaCl diminished at RH 65% and almost disappeared at RH 95%. The suppression of the solubility at RH 65% and RH 95% was mainly caused by the loss of the intrinsic salt-solubility of myosin, regardless of the degree of the Maillard reaction. The loss of the salt-solubility of myosin during the reaction with glucose was effectively suppressed by controlling the relative humidity at less than 35% and increasing the glucose concentration to more than 0.08 mol/g H2O. These results indicate that the improvement of the solubility of Mf in a low-ionic-strength medium by the Maillard reaction with glucose is closely related to the salt-solubility of myosin, and the relative humidity and the glucose concentration are important factors in suppressing myosin heat denaturation.