Extraction And Functional Properties Of Protein From Chia(Salvia Hispanica L.) Seed

Chia(Salvia Hispanica L.),an annual crop native to Mexico and northern Guatemala.Chia seed has high nutritional valuecontains,rich in omega-3 unsaturated fatty acids,protein,dietary fiber,minerals and antioxidants.Chia seed cake was the by-product from chia seed by cold pressing oil extraction,which protein content can up to 30%-40%,chia seed protein is a kind of developing vegetable protein with high nutritional value and good quality.Chia seed cake contains about 18% of the oil was not extracted completely,which were unfavourable for the development and utilization of chia seed protein,Therefore,the preparation of protein should be conducted after chia seed cake was defatted.Chia seed cake as the research object,defatted by the organic solvent extraction for preparation of chia seed meal,then,extraction of chia seed protein from chia seed meal by using the method of alkali extraction,moreover,nutrition value and functional properties are also studied.This project aims to improve the utilization value of chia seed protein resource,provide data support for development of related product of chia seed protein,provide reference for the utilization of chia seed resources and new food research.The Specific research results are list as follow:1.Chia seed cake as the research object,n-hexane as de-fatting solution,with the residual oil ratio as the index,the process conditions of chia seed cake de-fatting were optimized by response surface methodology.The optimal extraction conditions were obtained by regression equation model as follows: leaching times 3,solid-liquid ratio1:6g/mL,leaching temperature 45℃and leaching time 75 min.And the average residual oil ratio was 0.56% through five parallel verification experiments.Compared to the theoretical value,the relative error was 1.8%.2.Chia seed meal as the research object,extraction of chia seed protein from chia seed meal by using the method of alkali extraction and acid precipitation was investigated.Amino acids composition of the chia seed protein were also analyzed.The results showed that the pI of the chia seed protein was 4.2,the optimum extraction parameters were liquid-solid ratio 35 mL/g,pH value 9.5,temperature 45 ℃,time 40 mins and extraction times twice.The protein extraction rate reached 61.52%.The results of the amino acids analysis showed that chia seed protein has comprehensive amino acids and essential amino acids content in line with the(FAO/WHO)ideal mode.The total essential amino acids/total amino acids(TEAA/TAA)and total essential amino acids/total none essential amino acids(TEAA/TNEAA)were 35.40% and 54.80%,respectively.The total essential amino acids content in chia seed protein was higher than that of soy protein isolate(SPI).Based on the obtained data,whole hen’s egg protein and the FAO/WHO reference model of amino acid score(AAS)and chemical score(CS)were used to evaluate the nutritional values of the chia seed protein in comparison with SPI.AAS and CS indicated the first limiting amino acids in chia seed protein were lysine andisoleu,respectively.The essential amino acid index(EAAI)of chia seed protein and SPI were 86.69 and 73.85,respectively,indicating that chia seed is a good source of proteins with high nutritional value.Moreover,SDS-PAGE was used to analyze the subunit molecular weight distribution of prepared chia seed protein.It was determined that this protein mainly consisted of two subnits with molecular weight from 18 to 25 kiloDalton.3.Chia seed protein as the research object,compared with SPI,the effects of pH,temperature,NaCl concentration,sucrose concentration,protein concentration on functional properties(solubility,water-holding capacity,oil-absorbing capacity,emulsifying capacity,emulsion stability,foaming capacity and foam stability)were investigated systematically.The results showed that the water holding capacity,oil-binding capacity and foaming stability of chia seed protein were higher than that of SPI,while the solubility,emulsifying property,emulsifying stability and foaming ability were lower than SPI.The solubility,water-holding capacity,oil-binding capacity,emulsifying capacity and emulsion stability,foaming capacity of protein were the lowest around isoelectric point.Functional properties were significantly improved by suitable heating(20~50 ℃),but exposure to excessive heat caused a continuous decrease in the various functional properties.The solubility,water-holding capacity,oil-binding capacity,emulsifying properties and foaming properties could be improved by increased suitable NaCl concentration(0~1.0mol/L).However,higher level of NaCl concentration had a negative effect on these properties.The emulsifying capacity,emulsion stability,foaming capacity and foam stability of protein were improved by increasing the protein concentration,but at a level of 4 ~ 5 g/100 m L,no obvious change in emulsifying capacity,emulsion stability,foaming capacity and foam stabilitywas observed.This paper makes a preliminary exploration of extraction and functional properties of protein from chia seed,The follow-up keystone of research are effectively improve the extraction rate of chia seed protein,improve the solubility of chia seed protein,and explore its relationship between functional properties and molecular structure.