Enzymatic Extraction,Functional Properties And Application Of Flax Protein

Flaxseed meal is the residue of flaxseed oil extraction.In China,flaxseed meal is mainly used as part of animal feed,which results in ineffcient appliance of flaxseed meal.Hence the utilization of flaxseed meal in developing new food supplies are able to enlarge enterprise marginal benefiits,therefore it maintains positive significance in deep processing and utilizing flaxseed meal.The following experiment took axseed meal as raw material to extract flaxseed protein in dopting double enzyme complex method.Single factor test and response surface software techniques were used to optimize the extraction process of flaxseed protein.Meanwhile the functional properties of flaxseed protein extracted by double enzyme complex method and alkali solution acid precipitation method were compared for further results.The molecular weight and amino acid composition of purified flaxseed protein were determined.The flaxseed protein was also determined applied in ice cream produce.The experiment results are as follows:In the experiment,cell wall breaking enzymes and protease were adopted in assisting the extraction of flax protein.Optimum single enzyme was selected as ?-amylase and alkaline protease.Single factor test was used to further reduce the scope of the factors.On basis of single factor,response surface optimization was adopted.Optimal parameters of?-amylase extraction of flax protein were: 2.5% enzyme added,temperature of 60 ?,p H of 6 and time of 4 hours.Extraction rate was64.15%.Optimum technological parameters of extracting flax protein with alkaline protease are: 1% enzyme added,47.5 ?,p H 10.1 and time 3 h,the extraction rate is 72.16%.The flax protein was extracted by ?-amylaseand alkaline protease respectively,and the extraction rate was 86.61%.According to the suitable technological conditions of extracting flax protein,a large number of flax protein extracts were prepared.Afterwards filtration was carried out to remove macromolecular impurities,further concentrated by ultrafiltration tube,and dextran gel chromatography(G100)was adopted to remove the residual small molecules.Purified linseed protein extract was precipitated by chitosan and vacuum freeze-dried.The purity of flaxseed protein was 86.25%.The results showed the amino acid content of flax protein extracted by double enzyme complex method was slightly higher than that extracted by alkali soluble acid precipitation method.The molecular weight of flaxseed protein was determined by polyacrylamide gel electrophoresis(SDS-PAGE).The results showed the bands of linseed protein extracted by alkali dissolution and acid precipitation were clearer.The molecular weight range of linseed protein extracted by double enzyme combined method and alkali soluble acid precipitation method was identical,which was in the range of 17-20 k Da and 35-48 k Da respectively.On the purpose of applying flax protein in food produce,the functional properties of flax protein extracted by double enzyme complex method and alkali solution acid precipitation method were compared and analyzed.Foaming and foam stability,emulsifying and emulsifying stability,viscosity,water holding capacity,oil holding capacity and solubility of flaxseed protein extracted by double enzyme combined method and alkali soluble acid precipitation method were determined and compared.The results showed that the emulsifying property,emulsifying stability,solubility,foaming ability and foam stability of linseed protein extracted by double enzyme complex technic were better than those of alkali dissolution and acid precipitation under most conditions.The water holding capacity of linseed protein extracted by alkali dissolution and acid precipitation was preferred than that of double enzyme combination undermost conditions.Flax protein was used in ice cream produce The formula of flax protein ice cream was optimized by single factor and orthogonal test.The results showed that the optimum formula was: flax protein 3%,skimmed milk powder 13%,cream 15%,sucrose 16%.With this condition,the ice cream produce had uniform color,light brown color,light milk aroma and delicate taste.It is an efficient method to extract linseed protein by double enzyme complex method,and the functional properties of the obtained linseed protein are preferred than that by alkali solution and acid precipitation method,which can be well applied in ice cream produce.