Peptides Derived From Walnut Protein

Protein is one of the most important nutrients which human needs. They are absorbed by body in amino acids or peptides. In these years studies have shown that small peptides (2-7 amino acids) have important physiological functions in human body, and the absorption ratio of these peptides is much better than pure amino acid.The process of this experiment is this: proteins derived from walnuts were hydrolyzed, and peptides were separated from the hydrolysate.Walnuts proteins were obtained after the steps of beating, adjusting PH, and centrifugalizing.The enzyme in this experiment is papain, for the active range of papain is much wider.The hydrolysis of papain: This is an important step in the whole process of obtaining peptides from walnut protein. Because the same enzyme on the different proteins will be under different condition, to know the best condition, the analysis of single factor is necessary such as PH, temperature, substrate concentration, dose of enzyme, and reaction time. Considering other factors, temperature and time were determined. They are 40 癈 and 2h. Do experiment of orthogonal design including the other three factors: PH, substrate concentration, dose of enzyme. The best condition was made through analysis of variance on the results. They are temperature 40"C, PH is 9.0, substrate concentration is 40mg/ml, dose of enzyme is 150.65u/g, reaction time is 2h, the degree of hydrolysis is about 20%.Heat the hydrolysate in 95 癈 hot water to make enzyme inactive, adjust PH, centrifugalize, and concentrate the clear liquid. There are mixtures of peptides in the concentration liquid, so the small peptides have to be separated from the mixture.The gel filtration was adopted in this process of seperation. The gel is SephadexG-25. The eluate is 0.1NHCL, and the elution speed is 2.2ml/5min.The outside volume (Vo) of the gel is 26ml, and the inside volume (Vi) is 69ml. Concentration liquid was put on, eluted by the eluent, and then the eluates was collected. Detect the absorbance of the eluates under 280nm, and draw the elution curve. Remove the eluates of very large molecular weight and the eluates of molecular weight equal to the pure amino acid according to the Vo and Vi, and the left is the peptide mixture which the average molecular weight is about 5000.These peptides product was obtained after concentration and dry.Because the absorption ratio and speed of small peptides are much better than pure amino acid, and there will be no side effect on the synthesis of body protein, so it is beneficial to the people who are deficient in amino acid absorption and the patient who has experienced the operation.Compared with amino acid transportation system, the absorption of peptides is quick, low consumption on energy, not easy to be saturated and there is no competition and inhibition between peptides. So the absorption of peptides has advantages of high efficiency and high speed.The peptides derived from walnut protein by hydrolysis of papain can be used as functional food. And the method has so many advantages such a low cost, large production, high speed, that it is suitable for the industry production.