Extraction,Purification And Characteristics Of Okra Seed Protein

Okra seeds contain rich oil resources,which are usually used to press oil.After pressing oil,the okra seed meal are mostly treated as animal feed.The protein content is up to 30% in okra seed meal,and the most lack of human nutrition intake is protein.The okra seed protein can be used a source of high quality protein resources.But the fried denatures protein before pressing,which will make it difficult to extract protein.This subject has studied the extraction,purification,characteristics of okra seed protein,and the influence of frying on the protein.The specific research contents and results are as follows:(1)The okra seeds were degreased by ultrasound-assisted method.Under the optimal conditions,the oil extraction rate of okra was 91.18%.Alkali-solution and acid-isolation method was used to extract protein from degreasing okra seed meal.The isoelectric point of okra seed protein was:4.1~4.2.On the basis of the single factor experiment,the optimum process conditions were obtained by response surface method: solid-liquid ratio 1:30,p H10,temperature 55℃,time 90 min and times 2.Under the condition,yield of okra seed protein was 22.23%.(2)The DEAE-52 cellulose ion exchange chromatography and ultrafiltration were used to purify okra seed protein.The result showed ultrafiltration was suitable for the purification The ultrafiltration membrane and the environmental pH for the ultrafiltration of okra seed protein were determined with the rejection rate,membrane flux.The results showed under the condition of ultrafiltration membrane was 5kDa,p H was 10,okra seed protein purification is the best.(3)The functional characteristics,amino acid composition and structure of okra seed protein was studied.The results showed: pH was the most influential on solubility,the solubility was 93.14% at p H 11;when temperature was 50°C,the best holding oil capacity was 2.288g/g;ionic strength was the most influential on water binding capacity,the best water binding capacity was3.956g/g when NaCl concentration was 0.6 mol/L;when protein concentration was 3%,the best foaming was 26.00%;while the foaming stability was getting better with increasing concentration.The denaturation temperature of okra seed protein was determined by DSC curve.When moisture content of protein was40%,the denaturation temperature was 56℃.Okra seed protein contained 17 kinds of amino acids with a content of 76.19%,which had high nutritional value.SDS-PAGE electrophoretogram of okra seed protein showed that the protein was a small molecule protein with the major subunits distributed in the range of 10 kDa ~55 k Da.The secondary structure was characterized by infrared spectroscopy,which proved okra seed protein had characteristic absorption peaks of the amide bands.(4)By comparing the protein differences between solvent extraction of okra seed meal and frying press of okra seed meal,getting the effect of frying on protein was: the isoelectric point,solubility and nutritional value decreased;the content of albumin and globulin decreased,the content of the glutelin,alcohol soluble protein and compound protein increased;the degree of denaturation was89.05%;α-helix and random curl decreased,and β-sheet and β-turn increased in the protein secondary structure.The fried press okra meal protein was extracted by alkali dissolving acid sedimentation,salting out,alcohol method and other methods,result showed that alcohol concentration had the highest extraction rate,which was 27.53%.Heating and enzymatic methods were used to modify okra seed protein and ACFPOP(alcohol concentrate frying press okra protein),Compared with the change of functional characteristics before and after the modification,In addition to the foaming properties of okra seed protein decreased by alcalase,other properties were increased.Scanning electron microscope was used to observe the microscopic conformation of the protein.The results showed that the modified okra seed protein changed from granular to flaky,alcohol leached okra meal protein concentrate modified by heating particles dispersed smaller,the enzyme-modified particles become loose floc.The above study shows that the okra seed protein has rich nutritional value and can be used as raw material or accessory for food processing.The functional characteristics of the frying pressed okra protein after modification have been improved,and can be further processed and utilized.