Aqueous Enzymatic Extraction Of Corn Germ Oil And Reclaiming Protein

Corn germ is a by-product of corn starch or alcohol industry and rich in oil content. Theprotein of corn germ is mostly albumin and globulin and the composition of the amino acid issimilar to that of egg white. Thus it can be seen that corn germ is not only oil plant resourcebut also protein resource. Aqueous enzymatic extraction of corn germ oil, which based onmechanical and enzymatic degradation of cell wall of corn germ, was a new way of oilproduction. The one of advantages of aqueous enzymatic extraction was that oil andhydrolyzed protein of corn germ could be obtained at the same time. The objective of thisdissertation was to reduce operating costs through research and development of thetechnology.The process of aqueous enzymatic extraction of corn germ oil was established. Theresults have shown that the yield of free oil depended on the treatment of raw material,hydrothermal pretreatment (time, temperature and citrate concentration), grinding degree,enzyme preparation, ratio of enzyme and time of enzymatic reaction. In this experiment theoptimum parameters were as follows. Frozen corn germ was heated with 0.05mol/L citratesolution, at 112℃,for 65min, milled by passing a vibratory mill for one time, treated at 40℃with 2.5% proteinase (based on corn germ mass) for 5h , and then treated at 50℃ with 1.5%cellulase (based on corn germ mass) for 11h. Finally the free oil ratio obtained was as much as91%.The diametric distribution and the microscope structure of particles were studied. Theresults showed that the cytoarchitecture of corn germ were broken down after hydrothermalpretreatment. The particle size was minished and slurry was rarefied along with proteinasedegradation. The particle size was smaller and free oil came out after cellulase hydrolyzation.The particle size of emulsion was within 0.4-3000um and most belonged to 50-1000um. Theemulsion consisted of non-discomposed cell group, the pieces of cell, emulsifying oil dropletand visible corn piece and beard. Above results suggested that the emulsion wasn't a simpleO/W system, but was a complex suspension system.The hydrolyzed proteins were obtained through nano filtration , concentrating and drying.The nano filtration technology was effective to concentrate hydrolyzed protein and removesalt at the same time. The hydrolyzed protein contented 21.5% protein ( or peptide) and52.9% carbohydrate. Through determining the distribution of the molecular weight for variouscomponents in the resulted power. We could know that a majority of hydrolyzed proteins werepeptides, only a little were proteins. In addition, composition of amino acid was similar to thatof egg white including all essential amino acids.Scale-up experiment was carried out on the Flottweg Tricanter, which has solved theproblem of continuous separation oil, water and leavings and has confirmed the feasibility ofcontinuous production in factory. From the yield of oil, the Flottweg Tricanter was effective toaqueous enzymatic extraction of corn germ oil.