Preparation And Application Of Corn Germ Proteins And ACE Inhibitory Peptides

In order to utilize the plant protein resources and develop a kind of product with a hypotensive activity,corn germ protein were extracted from corn germ meal which was the byproduct producing corn germ oil.The bioactive corn germ peptides(CGPs)——corn germ angiotensin converting enzyme(ACE)inhibitory peptides were prepared by enzymolysis.Firstly,investigate the effect of five kinds food additives(reducing agents and surfactants)on corn germ protein yields.Secondly,the proteases were screened and optimized hydrolysis parameters were obtained in order to prepare high ACE inhibitory activity peptides.At last,a hypotensive corn germ peptides beverage with ACE inhibitory activity was developed.The main results were as follows:1.Optimization of corn germ protein extractionThe alkali-based extract protein method is better than that of saline-based method.The optimum extraction parameters of alkali-based method were:0.1M Na OH as extraction solvent,material-liquid ratio 1:15 g/ml,temperature 50?,the first extraction1.5 h,the secondary extraction 0.5h,protein extraction ratio reached 67.68%.The effects of reducing agents including Na₂SO₃,Na HSO₃and cysteine hydrochloride and surfactants such as Tween-20 and modified soy lecithin on corn germ protein extraction ratio were investigated.Either additives alone or in combination,the protein yields could not improve significantly.2.Determination of optimum hydrolysis conditionsThe ACE inhibitory activities of CGPs,degree of hydrolysis(DH)and functional properties(solubility,emulsibility,foamability)were measured to evaluated hydrolysis effect.Compared with Alcalase 2.4L and Trypsin,Promamex was a optimum enzyme.The ACE inhibitory activity of CGPs was improved by orthogonal test and the optimum hydrolysis parameters were:Corn germ protein concentration of 2.5%,Protamex dosage 7000U/g,50?,p H=7.0,and hydrolysis time of 2.5h.ACE inhibition rate of CGPs was 82.63%,and the DH reached 10.66%under this condition.3.Development of ACE inhibitory CGPs beverageThe parameters of ACE inhibitory CGPs beverage were determined by single-factor test,orthogonal test,sensory scores,centrifugal stability and stability factor.With CGPs as main ingredient,dosage of each accessory is:sugar 9%,citric acid 0.1%,malic acid0.15%,xanthan gum 0.07%,sodium alginate 0.09%,CMC-Na 0.09%.The beverage produced by the above process has both good taste and stability.