Study On Zein Extraction And Purification And Zein Plasticized Films

In this study, the extraction processes of zein from corn gluten meal were optimized, and then it was purified by size exclusion chromatography, decolorizing the zeaxanthin simultaneously. The functional characteristics of zein and the characters of plasticized zein films were studiedThe optimum parameter of magnetic strring zein extracts from CGM was 70% EtOH and CGM to solvent ration was 1:12(W/V), setting stirring temperature to 50℃and stirring speed 40, extracting 1.5 hours, the protein yield was 90.24% and protein content was 62.29%. The optimality condition for supersonic zein were 80% EtOH, the particle size of CGM was 80mu with CGM to solvent ration of 1:7(W/V), supersonic temperature was set to 45℃, extracting 46min by 60% power, the protein yield under which was 37.75% and protein content in the supersonic samples reached 78.17%.In this study, zein was purified by size exclusion chromatography. An column (1.6cm diameter,100 cm length) packed with LH-20 resin was equilibrated with 70% aqueous ethanol solution at room temperature. Twenty milliliters of the magnetic strring CGM extracts was loaded to the column with a flow rate of 0.6ml/min, samples were collected every 10 mins. The color of purified zein powder was even lighter than commercial zein, with a protein content of 90.52%. The pigment fraction was lutein, zeaxanthin, beta-cryptoxanthin and beta-carotene analysed by HPLC chromatograph. The odour in CGM was removed by ethanol extraction, that is conformed by GC-MS. Zein is low in water and fat retention, while accounts for 40% in emulsifying ability and emulsion stability.Oleic acid, PG, PEG-400 and TEG was plasticized in zein film with a weight content of 30%,50%,70%,50%,70%,100%,10%,20%,30% and 10%,20%,30% relatively. Zein films were dried on polypropylene dish in 60℃water bath kettle. Light transmittance of zein-plasticized films was obviously higher than pure zein film, PEG-400 and TEG plasticized films were smooth under SEM, PG plasticized films had pin holes, oleic acid plasticized films had many big holes. DSC thermograms showed that Tg of plasticized films decreased 15-55℃, compared to unplasticized zein film.30% TEG plasticized zein film had the lowest Tg of 135.3℃, while 30% PEG-400,70% PG,70% oleic acid plasticized films also had a relatively low Tg.Those zein films were confirmed in strong flexibility. The tension strength of zein films increased as the content of oleic acid decreased, while rose as the content of PG,PEG-400 and TEG rose.