Optimization Of Peptide Preparation Technology From Maca And Its Physicochemical Properties

Lepidium meyenii Walpers.（Maca）is rich in nutrients,especially high content of protein,10.2%¹8%,and there are many secondary metabolites,such as alkaloids,glucosinolates,polyphenols and so on.In this paper,Xinjiang yellow Maca powder taken as raw material.Frist,used ethanol water reflux method to remove soluble components of Maca,preparation of Maca alcohol.Second,used amylase to removel of starch,Maca protein was prepared.Thrid,protease hydrolyzad Maca protein which prepare for Maca peptide.Finally,tested antioxidant activity evaluation of Maca alcohol and Maca peptide.（1）The alkaloids extraction rate of Maca alcohol as response value,optimized the preparation of Maca alcohol with orthogonal test experiment.Under the condition of extraction temperature 85℃,55%ethanol concentration,solid-liquid ratio 1:10（g/mL）,time 1 h,The Maca alkaloids extraction rate of Maca alcohol was the highest,（90.21±0.35）%.（2）Compared the effects of acid protease,neutral protease,alkaline protease and papain respectively on Maca protein hydrolysis degree,determined the optimum enzyme is alkaline protease.The optimum conditions for enzymatic hydrolysis of Maca peptide by alkaline protease were as follow:time 4 h,pH 10.5,temperature 55℃,the amount of enzyme 1.6×10⁴ U/g,under this condition,the preparation of Maca polypeptide hydrolysis is（31.55±0.74）%.（3）Though·OH,DPPH·and O₂^-·scavenging activities were tested for antioxidant activity evaluation of Maca alcohol and Maca peptide.The results and conclusions were as follows:The antioxidant activity of Maca alcohol is positively correlated with the concentration.The scavenging capacity of same dilution Maca alcohol to the DPPH·is the best,·OH followed,O₂^-·is the weakest.Scavenging radicals ability of double dilution of Maca alcohol is maximum,the scavenging rate of DPPH was 94.44%,the scavenging rate of·OH was 85.05%,the scavenging rate of O₂^-·was 53.85%.Amino acid composition analysis of Maca alcohol,which contains 17 kinds of amino acids.Someaminoacidswithfreeradicalscavengingability:His,Lys,Tyr,Pro,Met,Cys,Arg,Glu accounting for 71.83%of the total amino acids contents.In addition,some soluble components,such as alkaloids,soluble polysaccharides and polyphenols,are dissolved.These substances all have certain antioxidant capacity.The IC₅₀ values of Maca peptide to·OH,DPPH·and O₂^-·were 0.85 mg/mL,0.44 mg/mL and 0.86 mg/mL,and showed a certain dose effect relationship.The IC50values of Vc to·OH,DPPH·and O₂^-·values were 0.44 mg/mL,0.32 mg/mL,0.32mg/mL,Vc’s antioxidant activity was better than Maca peptide.In pH4¹0,with the increase of pH value,the scavenging capacity of Maca peptide to·OH increased and then decreased,the scavenging rate of DPPH·decreased,and O₂^-·scavenging ability almost had no effect.Amino acid composition analysis of Maca peptide,found four kinds of amino acid content of Maca peptide Tyr,his,Lys,Pro were 16.98%.However,the peptide contains Tyr,his,Lys,Pro generally has strong antioxidant activity.This showed that there was a certain relationship between the amino acid composition of Maca peptide and the antioxidant activity.