Preparation Of Mulberry Leaf Protein And Study On The Quality Of Leaf Protein

Mulberry leaf is a homologous plant leaf identified by the national health department.Mulberry leaf protein,as a leaf protein of high protein content,has good food processing characteristics and antioxidant properties in vitro.At present,there are few studies on the related properties of mulberry leaf protein.In this experiment,we start from the optimization of extraction technology and methods,prepare edible mulberry leaf protein powder,study the change of active substance and related functional properties of mulberry leaf protein powder,and look forward to the future research direction in this field,for the development of mulberry leaf protein.It provides a theoretical basis for the application.This study consists of the following three parts:1.Mulberry leaf protein preparation and the evaluation of protein nutrition and processing characteristics.In this part,With 4 representative mulberry varieties,Shan sang 305,the Shinichinose,the Da 10 and he ye bai as the material,the mulberry leaf drying method,the crude protein extractant,the crude protein precipitation drying method and other important parameters were tested.The results showed that the optimum preparation process was as follows:mulberry leaves were dried by natural drying and soaked at 20 min at normal temperature at 5 g/L Na OH,1 h in water bath at 40 C,and the supernatant was collected.The protein was precipitated with 1 mol/L HCl at p H 3 at the isoelectric point of p H 3,and the leaf protein powder was obtained by drying or freeze drying.The extraction rate of protein from 4mulberry varieties reached 14.6%～15.3%,and the content of crude protein ranged from43.67%to 54.07%.Compared with drying,freeze-dried mulberry leaf crude protein powder showed better flavor characteristics.The processing properties of 4 varieties of mulberry leaf crude protein powder were compared.The quality of mulberry leaf crude protein powder of10 was better.The solubility,water holding,oil holding,foaming,foam stability,emulsifying and emulsifying stability of Da 10 are 78.7%,64%,4.9 m L/g,72%,62.3%,4 m²/g,43.6%respectively.The content of Pb and Cd in mulberry leaf protein powder is lower than the national food hygiene standard.The results showed that mulberry leaves could be used to prepare edible high grade vegetable protein powder.2.Analysis of active substances in mulberry leaf protein powderIn this part,the leaves of Shan sang 305,Shinichinose,Da 10 and he ye bai were used as materials.The leaf protein sediment was separated by the better extraction process,and the mulberry leaf protein powder was prepared by drying oven at 37 C.The content of active substances in leaf protein powder and mulberry leaf powder was analyzed and compared.The results showed that the content of flavonoids in fresh leaves,Da 10 and he ye bai leaf protein powder in fresh mulberry leaves increased（0.116～0.676 mg/g）,and the loss of flavonoids in shansang 305 dried leaf protein powder was 0.195 mg/g.The tannin content of 4 freeze-dried leaf protein powders increased significantly（P<0.01）and increased（1.303～5.733 mg/g）,and the overall loss of 1-deoxy monyjjin was significant（P<0.01）and decreased（4.637～6.403mg/g）.It can be seen that mulberry leaf protein powder contains more tannin and flavonoids than dry leaves of dried mulberry leaves after drying at 37 C3.Study on antioxidant activity of mulberry leaf protease hydrolysates in vitroIn this part,4 kinds of mulberry leaf protein precipitates were separated and separated from 4 kinds of mulberry leaves,and the medium and small molecules of sediment were removed by dialysis.The protein powder of mulberry leaf protein was obtained by vacuum freeze drying（-55,2.2Pa）.The hydrolysis of leaf protein was obtained by hydrolysis of pepsin,trypsin,neutral protease,papain and bromelain.The antioxidant capacity of five kinds of antioxidants in vitro was determined.The results showed that the antioxidative ability of trypsin and peptide after hydrolysis of neutral protease was stronger than that of the 5enzymes and those without enzymatic hydrolysis.The reduction rate of H₂O₂and the chelation rate of Fe²⁺were the highest.The reduction rate of polypeptides after Trypsin Hydrolysis to H₂O₂was 76.1～87%,Fe²⁺The chelating rate is 66.53～94.44%,and the reduction rate of H2O2 after neutral protease hydrolysis is 76.36～95.62%,and the chelating rate of Fe²⁺is 63.52～88.11%.Using animal trypsin as the hydrolase of new Lasse protein powder,the ultrafiltration test of different molecular weight of protein hydrolysate peptide was carried out.The results showed that the antioxidant capacity of M>30k Da crude protein peptide was generally better in the same concentration of polypeptide solution.