The Study For Comparative Characterization Among Deamidation Behavior Of Carboxylic Acid Deamidated Wheat Gluten And Reactive Mechanism

This study was focused on the moderate modification and degeneration of wheat gluten by citric acid deamidation upon hydrothermal treatment.The effect of aggregation of wheat gluten on degree of deamidaton,changes of conformation and functional characteristics for same deamidated degree of wheat gluten and the indissolvable reason of insoluble components of wheat gluten after deamidation were explored.The research was beneficial to realization of aggregative mechanism of wheat gluten in the process of organic acid deamidation.And the reason for improvement of functional properties of wheat gluten with organic acid deamidation which provided theories and instruction of methods for utility of wheat gluten was revealed.(1)By controlling concentration of wheat gluten from dilute to semi-concentrated regimes to control spacing among protein molecules,different concentrations of wheat gluten were deamidated with citric acid upon hydrothermal condition at 121 ?.It demonstrated that the aggregation state of native wheat gluten was closely related to the rate of deamidated wheat gluten upon moist heat treatment with citric acid.And the aggragation state of native wheat gluten was the most important factor for the unfolding degree of protein molecular and aggregation trends of wheat gluten.(2)Aggregative behavior of different native state of wheat gluten upon 121 ? with different processing time was investigated.Original aggregative state of wheat gluten had significantly impact on spread of protein structure and contact between hydrogen ions and amide groups and peptide bond.Furthermore,hydrogen ions from citric acid was susceptible to high molecular weight glutenin subunits.(3)Characterization among deamidation behavior of citric acid deamidated wheat gluten by altering acid concentration,deamidated time and temperature was studied.Results showed that conformation of 40%of deamidated degree of wheat gluten had significantly change.Moderate deamidated modification could improved the flexibility of wheat gluten while treatment temperature did not exceed 100 ? and acid concentration was appropriate.The same deamidated degree of wheat gluten belongs to one area when principal component analysis and agglomerative hierarchical clustering were used for 19 physical indexes of deamidated wheat gluten,demonstrating the change of processing conditions had a similar effect on aggregated state of the same deamidated degree of wheat gluten.(4)Ultrasonic and a-amlyse enzyme treatment were used for insoluble components of deamidated wheat gluten and its compents(gliadin and glutenin).Changes in SDS-PAGE,FTIR,molecular forces and intrinsic fluorescence emission spectroscopy were identified.It was found that starch granules had strong relationship with gliadin.They were encapsulated by water-insoluble gliadins at the surface by a large amount of hydrophobic interactions and hydrogen bonds to from a composite.And then these composites was entrapped in the interior of tridimensional network of glutenins.Formation of more closely structure among starch granules,gliadin and glutenin was a important factor for insolubility of deamidated wheat gluten.