Preparation, Application In The Emulsion And Oxidation Of Rice Glutelin Hydrolysate

Approximate 40% people in the world live on rice,comprising of 5%-10% protein, which values much in nutrition and hypoallergenic as a high quality plant protein. However, rice protein had a poor application in food industry, due to the insoluble gluten, which accounts for 80% of rice protein. In the study, the effects of enzymolysis on the functional properties of rice glutelin was investigated, followed by hydrolysis, the resultants were added to emulsion for studying the effect on it. Moreover, oxidation on emulsifying properties of RGH was investigated.The main results were as follows:The rice glutelin was extracted from rice protein by alkali extraction, and the protein content of rice glutelin was up to 90.69%. Trypsin was selected to modify rice glutelin, enzymatic hydrolyzed rice glutelin with different DH could be prepared by controlling the response time. When the time was 5min, 15 min, 60 min, 240 min, the enzymatic hydrolyzed rice glutelin with different DH(DH=5.88%, 8.44%, 10.30%, 16.37%) could be gotten. In order to record conveniently, DH was recorded as 6%, 8%, 10%, 16% instead of 5.88%, 8.44%, 10.30%, 16.37%. The effects of DH on the functional properties and secondary structure of protein were investigated. The results showed that functional propeties different changing approaching with the increasing DH. Solubility increased and emulsifying properties increased firstly and then decreased with the same as foaming properties,while surface hydrophobicity were exactly opposite. Followed by hydrolysis, capacity of oil holding was improved by over 40%. Moreover the FT-IR results also showed the propeties of rice glutelin were improved.Investigated by measuring emulsifying stability, microstructure, droplet sizedistribution, Zeta potential and oxidative stability. The results showed that based on the tendency of among DH, stability of emulsion and droplet size distribution, it revealed that the droplet size was getting larger and the number of droplet was getting small with the decreasing of DH,which resulting the difficulty of coalescence while the stability of emulsion was getting poorer. And all the four emulsion would coalescence to prevent static electricity.Static rheological properties showed that all the four emulsions were power law model instead of non-Newtonian fluids. Moreover, the emulsion at DH 16% showed the best oxidative stability whlie the other 3 showed minor difference. The results of TBARS showed similar tendency with POV.And the carbonyl content, free sulfhydryl, FT-IR, solubility and emulsifying properties of which rice glutelin hydrolysate were oxidized by the different concentrations of AAPH were evaluated. The results showed that content of carbonyl inscreased,while free sulfhydryl decreased, properties of solubility and emulsifying rose firstly and then droped with the increasing of AAPH, presenting that moderate oxidation could improve emulsifying properties of rice glutelin hydrolysate. Whlie the FT-IR data analysis shows that the secondary structure of rice glutelin hydrolysate has changed.