Extraction Technology And Properties Of Corn Germ Protein By Reverse Micelles

Corn germ was treated as rich resources of plant,the protein protein content of which wereabove20%, and have not been effectively used at present.In this paper, we used corn germ as raw material. After been degreased by supercriticalCO2fluid, we studied on extraction technology of protein from corn germ by reversedmicelles, and optimized the extraction process, then researched on the structure characteristicsand functional properties of corn germ protein isolate and its application in pork ham sausage.The extraction of corn germ protein by reversed micelles was divided into two steps--theforward extraction and the backward extraction. After optimizing the first step of theextraction, we obtained the best technological conditions of the forward extraction: AOTconcentration of2.19g per50mL isooctane, pH7.17, and temperature38℃. And under theseconditions, the forward extraction efficiency of corn germ protein achieved58.36%. Byresponse surface analysis, the best technological conditions of the backward extraction wereas blows: KCl concentration1.14mol/L, pH10.14, and time53min, and the backwardextraction efficiency of corn germ protein achieved64.57%. The final extraction efficiency ofcorn germ protein by reversed micelles was36.15%. After been concentrated, desalted,lyophilized, absterged, the protein content of corn germ protein isolate achieved81.26%.The results of studying on the functional properties of corn germ protein isolate showedthat: the solubility of corn germ protein isolate got the minimum value at pH4.In the givenrange, the rise of temperature and the increasing of the concentration of sodium chloridecontributed to the dissolution of corn germ protein isolate. The viscosity of corn germ proteinisolate was excellent when the pH was nearby isoelectric point and alkaline range or withtemprature from30℃to50℃. The WHC of corn germ protein isolate was much higher withConcentration of sodium chloride of0.15mol/L or temprature ranged from30℃~50℃. Withlower protein concentration or higher sugar concentration, corn germ protein isolate had betterfoaming ability and foam stability; and the foaming ability of corn germ protein isolate wasbetter than soybean protein isolate with the condition of lower protein concentration. Oilabsorption, emulsification and emulsion stability of corn germ protein isolate were superior tosoybean protein isolate, but the gel formative was at low level.The results of studying on the chemical compositions and structure properties of corngerm protein isolate showed that: the corn germ protein isolate was rich in essential aminoacid content, and the contents of Thr、Val、Phe、His were higher than the rcommended intake of FAO/WHO of adults and children, and the contents of Lys、Ile、Leu were a bit hagher thanthe rcommended intake of adults and were closing to the rcommended intake of children. Thecorn germ protein isolate contained much hydrophobic amino acids, and was a kind of acidprotein. The analysis of gel chromatography showed that the corn germ protein isolatecontained five components, and the molecular weight of which were359109Da、81203Da、47750Da、31225Da、13352Da respectively. The heat resistance and thermal stability of corngerm protein isolate were outstanding, and the results of DSC showed that the thermaldenaturation temperature was90.39℃and the denaturation enthalpy was122.4J/g. FT-IRanalyses of the secondary structure of corn germ protein isolate showed that the contents ofα-Helix、β-Turns and β-Sheet were43.55％、23.91％and11.85％respectively.The application of corn germ protein isolate in pork ham sausage showed that it couldenhance the sausage yield, and contributed to sensory evaluation and the qualitycharacteristics of pork ham sausage.