Application Of Nitrogen-assisted Positive Pressure Cavitation Technology In Extraction Of Hemp Seed Protein

Hemp seed is an underestimated agricultural and sideline product.The plant has high protein and oil content and is rich in nutrients.Most hemp seeds were used to squeeze oil,while the remaining dross has a low utilization rate and less research.In this paper,hemp seed from Bama,Guangxi,was selected as the research object.The positive pressure process generated by nitrogen was used to extract hemp kernel protein.Explore whether the nitrogen-assisted positive pressure cavitation technology has a positive effect on the extraction of hemp seed protein.(1)Use deoiled hemp seed as raw material.The positive pressure cavitation was produced by adding nitrogen to accelerate the extraction of protein.Take the protein yield as an evaluation index.Combine single factor test and response surface test.The effects of p H,temperature,time,material-to-liquid ratio and aeration rate on the extraction rate of protein were explored.The optimal extraction process was:lye p H:12,material-to-liquid ratio:1:50(g/m L),extraction temperature:52℃,nitrogen gas flow rate of1.6 L/min,and extraction time:50 min.Under these conditions,the hemp seed protein yield was 76.03%.It is significantly higher than 56.32%of the magnetic stirring method under the same conditions.Therefore,nitrogen-assisted positive pressure cavitation extraction technology can indeed increase the extraction rate of hemp seed protein.(2)Use deoiled hemp seed as raw material.The introduction of nitrogen gas produces positive pressure cavitation,which accelerates the enzymatic hydrolysis of hemp seed protein.Take the peptide yield as an evaluation index.Combine single factor test and response surface test.The effects of enzyme addition,temperature,time,material-to-liquid ratio and aeration rate on the yield of peptides were explored.The optimal extraction process was:enzyme addition:0.60%,nitrogen flow rate:1.6 L/min,temperature:65°C,time:55 min,adjusting p H to 8.0,and the yield was82.07%.It is significantly higher than 65.19%of the magnetic stirring method under the same conditions.Therefore,the nitrogen-assisted positive pressure cavitation preparation technology can indeed promote the proteolysis of hemp seed.Industrialized design of experimental equipment and applied to industrial production(3)Hemp seed polypeptide solution showed strong antioxidant activity in 6 kinds of antioxidant activity in vitro.In the three free radical scavenging experiments and the determination of total reducing power,a significant dose-effect relationship was reflected,and R~2 was all greater than0.99.Compared with the peptide solution prepared by the magnetic stirring method,it has different degrees of improvement in the five tests.The OH radical scavenging rate increased by 6.27%,the DPPH scavenging rate increased by 28.42%,the ABTS scavenging rate increased by 11.7%,the absorbance value of the total reducing power increased by 0.106,and the iron ion chelation rate increased by 20.57%.It shows that the nitrogen-assisted preparation of hemp seed peptide solution can indeed reduce the oxidation loss during the preparation process and improve the antioxidant performance of the peptide solution.(4)Four methods were used to extract hemp seed protein,and their physical and chemical properties were different.The color of the protein prepared by the alkaline solution method was brighter,and the color of the protein prepared by the enzymatic hydrolysis method was yellowish.The protein particles extracted with the aid of positive pressure cavitation are smaller,with porous surfaces and obvious layers.The protein content prepared by the positive pressure alkaline solution method was the highest at 93.79%,and the protein prepared by the positive pressure enzymatic hydrolysis method had the highest extraction rate at 46.16%.When the p H value is higher than 7.5,the solubility of barotropic alkali soluble protein was the best.Positive pressure enzymatic protein has good solubility at 80℃.The foaming ability of positive pressure enzymatic protein hydrolysis was weak,but the foam stability was strong.Positive pressure alkali-soluble protein has the strongest emulsification.The denaturation temperature of protein extracted by positive pressure was lower.The amino acid content and composition of hemp seed protein was very rich,especially the protein extracted by positive pressure alkaline solution method,its amino acid composition was more scientific and reasonable,very close to the ideal protein recommended by FAO/WHO.