Preparation Of Protein And Peptide From Coconut

Coconut is a high-quality agricultural product that can be regarded as,both fruit and oil plants.In most coconut-producing countries,coconut is the most important economic and industrial crop because coconut oil deriving from dried coconut is of great value and contains precious lauric acid.In addition to providing oil,coconut protein also contains fairly balanced amino acid compostion.It has a full range of 8 essential amino acids and a high nutritional value.It also has health functions such as lowering blood fat,lowering cholesterol,and suppressing hyperlipidemia.However,coconut is mainly used for the production of coconut oil and beverages at present,and cakes after oil extraction are directly wasted,which causes a serious waste of coconut protein resources.This paper aims to improve the utilization of coconut cakes,prepare high-purity coconut protein isolates and screen out better functional coconut peptides.The preparation process conditions were optimized by response surface and orthogonal tests.The amino acid composition and molecular weight distribution of the obtained products were examined.The functional properties of different products were compared and the theoretical basis for production application was provided.The main research contents and conclusions were as follows:(1)The coconut protein isolate was extracted with phosphate buffer solution Using defatted coconut powder as raw material.The effects of ratio of liquid to feed,pH,temperature,time and other factors on the extraction rate of coconut protein isolate were analyzed.The Plackett-Burman test was used to screen its influencing factors;response surface methodology was used to optimize the coconut protein extraction process,and finally the optimum extraction process of coconut protein was obtained.The optimum conditions were as follows: alkali dissolution time was 92.0mim,alkali dissolution pH was 10.0,acid precipitation time was 116.0min,acid precipitation pH was 4.5.Finally,through the verification test,the extraction rate of coconut protein isolate was 83.18%.(2)Using defatted coconut powder as raw material,the technology of extracting albumin,globulin,gliadin and glutenin from coconuts was studied by modified osboren method.By analyzing the effects of different factors on the protein extraction rate with the single-factor experiments,and then to optimize by using the orthogonal extraction experiment,the best extraction process was:(1)The ratio of liquid to material was 10:1(mL/g)and the extraction time was 4.0 hours.The extraction temperature was 50.0? the albumin extraction rate was 49.05%.(2)liquid to material ratio was 10:1(mL/g),extraction time was 4.0 hours,extraction temperature was 50.0?,NaCl concentration of 2.0%,globulin extraction rate of 46.65%.(3)liquid to material ratio of 12:1(mL/g),extraction time of 5.0 hours,extraction temperature of 55.0?,ethanol concentration of 75%,gliadin protein extraction rate of 18.01%.(4)liquid to material ratio was 10:1(mL/g),extraction time was 4.0 hours,the extraction temperature was 50.0?,alkali-soluble pH was 10.0,the extraction rate of gluten was 26.78%.(3)Amino acid compositions of different coconut proteins were analyzed and SDS-PAGE electrophoresis was applied to measure the molecular weight coconut protein.the types of Most of the amino acids in coconut protein were abundant.The electrophoresis analysis showed that in addition to albumin,there were two bands with relatively large molecular masses,and other molecular weights were relatively small,and overall it was a relatively high-quality protein.Finally,by comparing the functional properties of four coconut proteins under different conditions,the effects of different environments on functional properties were obtained.(4)Through optimization of proteases,alkaline proteases and flavour proteases were screened out to prepare coconut peptides,and the compounding ratio was determined to be 2:1.Based on the experiments of enzymatic hydrolysis pH,enzymatic hydrolysis temperature,and enzymatic hydrolysis time,based on the degree of hydrolysis,DPPH,and ABTS,the response surface methodology was optimized using the Central-Composite Design to obtain the optimal conditions for peptide preparation.The optimum conditions were as follows: hydrolysis pH 8.5,hydrolysis temperature 51.0?,hydrolysis time 11.0h.The actual hydrolysis degree was 30.03%,the actual DPPH radical scavenging rate was 58.12%,and the actual ABTS radical scavenging rate was 80.47%.After optimization,the macroporous resin XAD-16 was used to separate the coconut peptides and eluted with different concentrations of ethanol solution.Five eluted peaks were obtained corresponding to five elution fractions.The DPPH and ABTS free radical scavenging abilities of different components were measured.XAD-30% had the best antioxidation and XAD-50% had the best.The amino acid composition and molecular weight distribution of different components were examined and analyzed.The amino acid composition and molecular weight distribution of different components were quite different,but the molecular weight distribution of different components was mainly below 2000 Da.The molecular weight distribution of eluted fraction XAD-10% was mainly concentrated below 500 Da,accounting for 64.5%;the molecular weight distribution of XAD-30% and XAD-50% was mainly concentrated between 500-3000 Da,XAD-30% and XAD-50% of the molecular weight ranged from 500 to 1000 Da,accounting for 31.4% and 41.4%,respectively.