| Walnut is a very high nutritional value of nuts with a high rate of oil,riching in mineral elements and vitamins,in addition to the high content of protein,amino acids are complete.Walnut has the function of protecting liver,preventing diabetes and improving memory,The walnut for direct consumption,but also for the production of walnut oil,walnut oil production process produces a large amount of walnut meal,the walnut meal is often not good use,or directly discarded as waste as feed,which not only makes the nutrients the loss,but also a waste of resources,in order to make use of the walnut meal resources,the experimental material is Xinjiang walnut meal,uses the different extraction method to carry on the protein extraction experiment,The main contents are as follows:1.Ultrasonic-assisted extraction of walnut meal protein experiment:single factor experiment mainly studied the extraction time,liquid ratio,temperature,pH on the protein extraction rate,on the basis of single factor using the response surface method to select the factor liquid ratio,temperature,PH was used to carry out the combination experiment of 3levels and 3 factors,and the optimum process parameters were optimized and determined.The optimum extraction conditions were as follows:time 1 h,ratio of material to liquid 1:20,pH 9,temperature 58℃.2.The response surface of walnut meal was extracted by ultrasonic assisted method.On the basis of single factor,solid-liquid ratio,temperature and pH were taken as free variables,The design combined with Design-Expert8.0,The two regression equation of protein extraction rate with pH,temperature and solid-liquid ratio was obtained.The regression coefficient of the model is R~2=0.9978,which shows that the fitting degree of the model is good,and 3 groups of experiments are carried out,respectively.The values of57.57%,58.89%,and 57.12%,respectively,the average yield of the experimental group is57.86%,which is close to the predicted value of three.3.Subcritical water-assisted extraction of walnut meal protein experiment:The effect of extraction time,ratio of material to liquid,temperature and pH on the extraction rate of protein was obtained by single factor experiment.The reaction experiment was carried out by optimizing the ratio of material to liquid,temperature and pH.The optimum extraction conditions were as follows:time 30 min,ratio of material to liquid 1:25,pH9.02,temperature 132.50℃.4.According to the response surface design of Design-Expert8.0,the ratio of material to liquid,temperature and pH were taken as free variables,and the protein extraction rate was the response value,and the two regression equation of protein extraction rate and the ratio of material to liquid,pH and temperature were obtained.the factors affecting the extraction rate of protein were:temperature>solid-liquid ratio>pH.Under the optimized conditions,the test was carried out,and the average value was 74.12%,which was close to the predicted value of 75.97%.5.Analysis of functional properties of protein,ultrasonic and sub critical water extraction of amino acids was found a total of 17 kinds of amino acids(tryptophan in alkaline hydrolysis),amino acids,essential amino acid content is reasonable,through significant analysis,ultrasonic and subcritical water extraction of essential amino acids was not significant,and the essential amino acid content is higher,further that the high nutritional value of walnut protein.The solubility of pH in protein analysis,near the isoelectric point,the solubility of ultrasonic and sub critical water proteins obtained near the isoelectric point of the lowest,in less than or greater than the isoelectric point,the solubility is increased,the critical water soluble protein was stronger than that of ultrasonic method.Protein solubility and emulsifying properties are closely linked,the emulsification of protein with pH showed a consistent change phenomenon,which is near the isoelectric point of emulsification is the lowest,in less than or greater than the isoelectric point,emulsification is increased,the critical water solubility than protein ultrasonic method. |
