The Research On The Modification And Functional Properties Of Rice Glutelin

Rice protein was widely favored for its high nutrition and low hypoallergenic character. Unfortunately, over 80% of the protein contained in rice is glutelin, and the solubility of rice protein is very low. The purpose of this paper was to discuss the effects of glutaminase on the molecular structure and functional properties of rice glutelin.To discuss the influence of the ratio of PG and protein, reaction temperature and pH to deamidated process, using deamidation degree (DD) and solubility as indexes. (1) Better reaction conditions determined by single factor test were following: the ratio of PG and protein is 1:7~1:5, 35~40℃, pH was 6.0~7.0, the DD reach to 35%, solubility was more than 70%. (2) The process conditions were optimized by Orthogonal on the base of the results of single factor test. The optimal conditions which were the ratio of PG and protein is 1:7, 37℃, pH7.0, the DD reach to 52.76%, solubility was 93.78%.To study the functional properties of rice glutelin and glutaminase-deamidated samples. The results showed that there was a significant increase (up to 96.99%) of solubility of glutaminase-deamidated rice glutelin in neutral buffer. Emulsifying capacity were also improved at pH7, and samples deamidated for 1~12 h yielded better emulsion; besides, the emulsifying stability were also improved markedly at pH3 after enzyme-reaction for 1~5 h. Deamidated samples demonstrated the best foaming ability at pH3, while both the foaming stability and viscosity decreased with the increase of enzyme reaction. In addition, compared to the original rice glutelin, the water bonding capacity and fat bonding capacity of deamidated samples were improved and increased 1.75~2.03 times and 1.58-1.94 times.To research the change of the molecular structure of rice glutelin and glutaminase - deamidated samples. The result of micorstructure (3000×) testify that the aggregation degree of the rice glutelin diminishes with the increasing deamidation degree. The longer the hydrolysis time, the protein polymer andα-helix structure reduced, zeta potential increased gradually; The content of disulfide bonds in the original rice glutelin are high, part of the disulfide bonds is destroyed during the initial deamidation stage, but the content of disulfid bonds maintain steady after 1h. The thermal analysis indicates that the denaturation peak temperature of the glutelin decreases and the enthalpy increases with the increasing deamidation degree.