CA1086307A - Process for the isolation of proteins from rapeseed - Google Patents
Process for the isolation of proteins from rapeseedInfo
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- CA1086307A CA1086307A CA260,900A CA260900A CA1086307A CA 1086307 A CA1086307 A CA 1086307A CA 260900 A CA260900 A CA 260900A CA 1086307 A CA1086307 A CA 1086307A
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-
- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23J—PROTEIN COMPOSITIONS FOR FOODSTUFFS; WORKING-UP PROTEINS FOR FOODSTUFFS; PHOSPHATIDE COMPOSITIONS FOR FOODSTUFFS
- A23J1/00—Obtaining protein compositions for foodstuffs; Bulk opening of eggs and separation of yolks from whites
- A23J1/14—Obtaining protein compositions for foodstuffs; Bulk opening of eggs and separation of yolks from whites from leguminous or other vegetable seeds; from press-cake or oil-bearing seeds
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- Peptides Or Proteins (AREA)
Abstract
Abstract of the disclosure A countercurrent procedure for the extraction of protein from defatted rapeseed meal is described. Using 0.02 N NaOH and a meal to solvent ratio of 1:25 as much as 94 % of meal nitrogen is extracted. A two step precipitation, first at pH 6.0 and then at pH 3.6, the two isoelectric points of the protein in the extract, affords two protein fractions, which contain 69.4 % and 24.3 % of the meal protein, respectively. After washing the curds with water and drying with acetone two highly pure isolates are obtained. Protein Isolate I, light grey, contains 92.9 % protein and Protein Isolate II, white, contains 98.6 % protein, both on a dry weight basis. These protein isolates are light colored, bland products having a foam stability higher than soybean protein.
Their amino acid composition shows adequate amounts of isoleucine and sulphur amino acids. Nutritional experiments prove better performance of the protein isolates as compared to the corres-ponding meals.
Their amino acid composition shows adequate amounts of isoleucine and sulphur amino acids. Nutritional experiments prove better performance of the protein isolates as compared to the corres-ponding meals.
Description
108630~
Background of the invention , .
This invention relates to a process for the preparation of highly pure proteins from rapeseed.
In view of the world-wide shortage in proteins, oilseeds such as soybean, peanut and cottonseed are becoming of increasing importance as sources for the production of edible proteins. Rapeseed, Brassica napus, which is the major oilseed crop of the temperate zones, had so far found little application in the production of protein, mainly due to the presence of undesirable constituents, such as erucic acid and glucosinolates, in the seeds. The breeding of new varieties of rapeseed for better quality of oil and meal have led to improved nutritional properties of rapeseed products.
The seed oils of these new varieties are free or almost free of erucic acid and the meals contain much smaller proportions of glucosinolates than conven-' tional rapeseed.
According to estimates of the United Nations Food and Agriculture Organization (FAO), by 1980, the world production of rapeseed can be expected ` to reach at least 12 mill. tons, annually. The new varieties of rapeseed will contribute substantially to filling the world's need of edible protein, provided suitable processes for the isolation of rapeseed protein can be found. Moreover, rapeseed proteins may be used in preparing technical pro-ducts, such as plastics, coatings and adhesives.
In recent years, considerable efforts has been made to find con-ditions for the removal of toxic substances from rapeseed. It has been possible to obtain 'protein concentrates' which contain 50-60 % of protein ; from some oilseeds, such as soybean and cottonseed, simply by dehulling the seeds and extracting the oils. Similarly, protein concentrates have also been prepared from conventional rapeseed by dehulling, extraction of .
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; ~0863()~7 glucosinolates and defatting. The yields of rapeseed protein concentrates have ranged from 23 to 28 % of the seeds.
Protein concentrates from soybeanJ cottonseed and, to a very small extend, from rapeseed, are finding use as animal feed. For human consumption, however, and in most technical applications, proteins of much higher purity, 'protein isolates', are required.
In the isolation of proteins from oilseeds on an industrial scale, ; two major steps are usually involved: Firstly, the proteins are extracted from defatted meal with water or an aqueous electrolyte solution. Secondly, the proteins are recovered from the extracts either by lypholization, drying or precipitation.
The extraction of the proteins is carried out either by single step or multiple stage processes using one or more than one solvents. All of these procedures require rather large volumes of solvent to attain a satis-factory degree of extraction. The recovery of proteins by lypholization or drying leads to products containing practically all the protein present in the extract. These products, however, are contaminated with non-protein material derived from the meal and the solvent. Alternatively, the proteins are recovered from the extract at the mean isoelectric point. The proteins ~; 20 isolated this way might be of higher purity than those obtained by lypholiza-tion or drying of the extracts, but the yields are generally lower.
Summary of the invention The present invention is directed toward a process for the pro-duction of protein isolates which are free of insoluble and, especially for children, indigestable carbohydrates, free of factors which are detrimental to health and free of undesirable flavor constituents or bitter principles or other components that might be harmful in human nutrition. These protein
Background of the invention , .
This invention relates to a process for the preparation of highly pure proteins from rapeseed.
In view of the world-wide shortage in proteins, oilseeds such as soybean, peanut and cottonseed are becoming of increasing importance as sources for the production of edible proteins. Rapeseed, Brassica napus, which is the major oilseed crop of the temperate zones, had so far found little application in the production of protein, mainly due to the presence of undesirable constituents, such as erucic acid and glucosinolates, in the seeds. The breeding of new varieties of rapeseed for better quality of oil and meal have led to improved nutritional properties of rapeseed products.
The seed oils of these new varieties are free or almost free of erucic acid and the meals contain much smaller proportions of glucosinolates than conven-' tional rapeseed.
According to estimates of the United Nations Food and Agriculture Organization (FAO), by 1980, the world production of rapeseed can be expected ` to reach at least 12 mill. tons, annually. The new varieties of rapeseed will contribute substantially to filling the world's need of edible protein, provided suitable processes for the isolation of rapeseed protein can be found. Moreover, rapeseed proteins may be used in preparing technical pro-ducts, such as plastics, coatings and adhesives.
In recent years, considerable efforts has been made to find con-ditions for the removal of toxic substances from rapeseed. It has been possible to obtain 'protein concentrates' which contain 50-60 % of protein ; from some oilseeds, such as soybean and cottonseed, simply by dehulling the seeds and extracting the oils. Similarly, protein concentrates have also been prepared from conventional rapeseed by dehulling, extraction of .
.
., . . . :, ~ . .. .. : . : , .. . .
; ~0863()~7 glucosinolates and defatting. The yields of rapeseed protein concentrates have ranged from 23 to 28 % of the seeds.
Protein concentrates from soybeanJ cottonseed and, to a very small extend, from rapeseed, are finding use as animal feed. For human consumption, however, and in most technical applications, proteins of much higher purity, 'protein isolates', are required.
In the isolation of proteins from oilseeds on an industrial scale, ; two major steps are usually involved: Firstly, the proteins are extracted from defatted meal with water or an aqueous electrolyte solution. Secondly, the proteins are recovered from the extracts either by lypholization, drying or precipitation.
The extraction of the proteins is carried out either by single step or multiple stage processes using one or more than one solvents. All of these procedures require rather large volumes of solvent to attain a satis-factory degree of extraction. The recovery of proteins by lypholization or drying leads to products containing practically all the protein present in the extract. These products, however, are contaminated with non-protein material derived from the meal and the solvent. Alternatively, the proteins are recovered from the extract at the mean isoelectric point. The proteins ~; 20 isolated this way might be of higher purity than those obtained by lypholiza-tion or drying of the extracts, but the yields are generally lower.
Summary of the invention The present invention is directed toward a process for the pro-duction of protein isolates which are free of insoluble and, especially for children, indigestable carbohydrates, free of factors which are detrimental to health and free of undesirable flavor constituents or bitter principles or other components that might be harmful in human nutrition. These protein
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~08630q isolates are suitable for human consumption as well as animal feed, they can be used to enrich other foodstuff with valuable proteins.
We have found that a maximum of protein present in defatted rape-seed meals can be extracted by a countercurrent process using water or aqueous solutions of electrolytes. In addition, we have discovered, that almost all of the protein present in the extract can be recovered by stepwise precipita-tion with aqueous mineral acid at different pH values.
Description of preferred embodiments The overall process for the preparation of protein isolates from rapeseed consists of two procedures: First, the proteins are extracted by a countercurrent process, continuously or discontinuously, using water, at pH 7.0, or aqueous solutions of sodium hydroxide or potassium hydroxide~ at pH values between 7.5 and 10.0, preferably at pH 9Ø Second, the proteins in the extract are precipitated in two consecutive steps by the addition of a mineral acid, such as hydrochloric acid, to attain a pH value between 5.0 and 6.5, preferably between pH 5.7 and 6.0 (Protein Isolate I), and then a pH value between 3.0 and 4.0, preferably pH 3.6 (Protein Isolate II). The precipitated proteins are washed with water and/or an organic solvent and, after filtration, they are dried in the usual manner.
The major advantages of the countercurrent extraction are, - almost quantitative dissolution (>95%) of protein at - least requirement of sdlvents and chemicals due to optimal utilization of the dissolving capacity of the solvent, - easy adaptibility to either a continuous or discontinuous process, - low space requirement of the plant due to the - small volume of equipment, and also, - low cost of plant, equipment, utilities and operation.
l(~B630q The major advantages of the stepwise precipitation of proteins at different pH values are, - the almost quantitative recovery of proteins from the extract at a minimum of chemicals and energy, - the feasibility of continuous or discontinuous processing, - the availability of two or more distinct types of proteins, - the very high protein content (>95%) of the products isolated~
- the negligible content of glucosinolates in the protein isolates and - the favorable amino acid composition of the protein isolates.
The protein isolates have a light color, bland taste and no odor;
they are suitable for human consumption as well as for various technical applications.
The entire process described in this invention is feasible on a large scale because each of the two procedures involved, - extraction of the proteins from defatted meal as well as precipitation of the proteins from the extract, - can be carried out in a continuous fashion. The overall yield of protein isolates is very high because each of these two procedures results in high recovery. Both the countercurrent extraction and the step-wise precipitation of proteins, as unit processes, contribute to the low cost of the isolation of proteins from rapeseed. The solid residue remaining after extraction of the proteins has a high fiber content and may serve as a filler, whereas the liquid remaining after precipitation, due to its high ; carbohydrate content, may be used in fermentation industry.
In conclusion, the process described constitutes a significant advance in the isolation of proteins from rapeseed. Both the countercurrent extraction of proteins and their stepwise precipitation and certainly, the combination of these processes are entirely new.
- . . : ., ... :
10863~7 The following specific examples illustrate the present invention : more fully. These two examples are for illustrative purposes only and are not ~- intended to limit the scope of the invention.
Example I
Figure 1 is a schematic representation of the countercurrent ex-traction of proteins from defatted oilseeds.
Fresh solvent meal t meal t meal 1 meal Stage A I l ~ J I ~ IV Extract A
Fresh solvent from ~ from t from 1 from Stage B Stage A ~ Stage A ~ Stage A ~ Stage A Extract B
Fresh solvent from ~ from ~ from ~ from Stage C Stage B ~ Stage B ~ Stage B ~ Stage B
Extract C
Fresh solvent from l from ~ from ~ from Stage D Stage C ~ Stage C J Stage C ~ Stage C Extract D
Figure 1: Sche~e for the countercurrent extraction of proteins.
108630q In a typical example, four 250 g samples of hexane-defatted rapeseed meal ~Brassica napus, Erglu), designated I-IV, were extracted with 0.02 M sodium hydroxide. In each of the four stages, A-D, the first sample was extracted with 6250 ml of fresh solvent at a meal to solvent ratio of 1:25. Extraction was carried out at ambient temperature for 10 minutes using a high-speed homogenizer. Subsequently, the samples were filtered under vacuum through cotton cloth. At each stage the filtrate from one sample was used to extract the next sample after measuring its volume and taking aliquots for nitrogen determination. At the beginning of each stage, the first sample in the previous stage was moved to the end of the series. The final extracts from the four stages were combined (pH 9.2), centrifuged at 5000 x g for 15 m mutes, and stored at 5C. Out of the 25 liters of 0.02 M sodium hydroxide used a total of 23 liters of extract was recovered. The results of the countercurrent extraction are presented in Table 1. The percentage of meal nitrogen extracted from the sample was calculated from the total amount of nitrogen of protein extracted up to the stage involved, and the amount of nitrogen originally present in the sample. The percentage of total meal nitrogen extracted at the various stages was calculated from the nitrogen content of protein extracts obtained-from-the four samples, at a given stage, and the amount of nitrogen originally-present in the four samples. The results show that about 94 % of the nitrogen present in the meal is ex-tracted.
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`: 108630q , Table ]: Countercurrent extraction of rapeseed (Brassica napus, Erglu) protein Extraction Sample Meal Nitrogen Total Meal Extracted from Nitrogen Extracted Stage No. the sample at each Stage (%~ (%) .
A I 67.1 II 12.0 III 31.1 rv 26.0 34.1 B II 90.6 III 49.1 IV 48.8 I 71.0 30.8 C III 83.4 IU 81.9 I 82.1 II 93.1 20.3 D IV 97.2 I 92.0 II 94.2 III 91.2 8.6 It is obvious that the countercurrent extraction of proteins as described in the present example offers great advantages over single step extractions-becaus-e of the high degree of protein recovery at a minimum re-quirement of solvent. Anothe~ major advantage of working with more concen-trated suspensions in a countercurrent process is that less material has to be treated for a very high output. The air-dried residue resulting from the countercurrent extraction contained 4.Q % protein and 21.1 % fiber.
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1~8630~7 The combined protein extract (23 liters) was transferred to a pre-cipitation vat. This solution, which contained soluble proteins, carbo-hydrates, minerals and glucosinolates had a pH value of 9.2; it was acidified to a pH value of 6.0 by the addition of 93 ml of 6 N hydrochloric acid in order to precipitate "Protein Isolate I". The protein curd was allowed to settle for about two hours. The supernatent liquid was siphoned off and transferred to another precipitation vat. The precipitated curd was centri-fuged at 5000 x g for 10 minutes and the supernatent was added to the solution in the second vat. The curd was washed with 400 ml of water and the washings were combined with the solution in the vat. The water-washed curd was then leached twice with 400 ml, each, of acetone. The protein isolate was air-dried at room temperature, Protein Isolate I (220 g) is light grey and has a bland taste.
The combined supernatent and the water washings from Protein Isolate I (pH ~.21 were acidified to a pH value of 3.6 by the addition of 103 ml of 6 N hydrochloric acid in order to precipitate "Protein Isolate II".
The protein curd was allowed to settle for 4 hours. The supernatent liquid was siphoned off and discarded. The precipitated curd of Protein Isolate II
was washed once with 200 ml of water and twice with 200 ml of acetone, each.
Protein Isolate II was air-dried at room temperature. Protein Isolate II (77 is white and has a bland taste.
The yields of Protein Isolates I and II and the total yield are as follows:
Protein Isolate I Protein Isolate II Total ~ % % %
Yield65.2 22.9 88.1 ,, , ., . , :.
1~8630q Analyses of the two rapeseed protein isolates are given in Table 2.
Table 2: Analyses of rapeseed ~Brassica napus, Erglu) protein isolates Protein Isolate I Protein Isolate II
Moisture % 10.5 8.1 Protein (dry basis) %
~% protein-N x 6.25) 92.9 98.6 Lipids % o.oo o.oo Ash % 0.70 0.31 Crude fiber % - 0.06 0.02 Glycosinolates % traces traces Static foam (~) 310 395 .
These analytical data show that the protein isolates are of high purity. These isolates conta~n little ash and fiber, and they are free of glucosinolates and other toxic ingredients. The sigma values indicate that the two isolates from rapeseed yield foams more than twice as stable as foams produced from commercial partially degraded soy protein.
Analyses of the amino acid composition of the two isolates show a fairly hîgh lysine content. Isoleucine, which is considered the limiting amino acid in rapeseed meal, occurs at a higher level in the isolates than in the meal used as starting material.
It is cl~early demonstrated by this example that pure, light colored, bland protein isolates having a desirable amino acid composition can be obtain-ed from rapeseed (Erglu) at a high yield through a combination of counter-current extraction and stepwise precipitation.
Example II
The countercurrent extraction (Figure l) described was carried out _ g _ - .. :: . . , ~ ::.:- :,, :. ,. : :: ~ ::: ::, : -108630~7 on a large lot of hexane-defatted rapeseed meal (Brassica napus, Lesira).
Four 1250 g samples were extracted with 0.02 M sodium hydroxide solution using a ~eal to solvent ratio of 1:20. The mixture was filtered under a pressure of three atmospheres. The results of the countercurrent ex-traction are given in Table 3. The percentage of total meal nitrogen extract-ed at each stage was calculated from the amount of nitrogen in the protein extract at the stage involved and the amount of nitrogen origi~ally present in the four samples.
Table 3: Countercurrent extraction of rapeseed (Brassica napus, Lesira) .
1 0 protein Extaction Total Meal Nitrogen Stage Extracted at each Stage ~%) A 49.2 B 27.2 C 14.4 D 1.9 .
These data demonstr~te that even after scaling up the process, a high efficiency of the countercurrent extraction for the dissolution of the protein is obtained. As much as 93 % of the protein-nitrogen present in the meal is thus extracted at a minimum solvent requirement.
The combined extracts from the four stages ~91 liters) were centri-fuged at 5000 x g and transferred to a precipitation vat. The stepwise precipitation process as well as the washing and drying of the precipitated curds were carried out as in Example I. The extract having a pM value of 9.2 was acidified to pH 5.7 by the addition of 391 ml of 6 N hydrochloric acid in -:. ' :: : --1~8630r7 order to precipitate Protein Isolate I. Subsequently, Protein Isolate II was precipitated from the supernatent and washings at a pH value of 3.6 by the addition of 378 ml of 6 N hydrochloric acid. The air-dried Protein Isolate I
~1168 g) is light grey, and the air-dried Protein Isolate II ~287 g) is white.
Both isolates have bland taste.
The yields of Protein Isolates I and II and the total yield are as follows:
Protein Isolate I Protein Isolate II Total ~%) ~%) ~%) - Yield 73.2 18.0 91.2 Analyses of the two rapeseed protein isolates are given in Table 4 Table 4: Analysis of rapeseed (Brassica napus, Lesira) protein isolates . _ _ _ _ Protein Isolate I Protein Isolate II
~oisture % 7 3 7.2 Protein ~dry basis) %
C% protein-N x 6.25) 99.6 99.3 Lipids % traces traces Ash % 0 04 Crude fiber % traces traces Glucosinolates % traces traces Static foam ~) 411 450 These analytical data show that the protein isolates are of high purity. These isolates contain little ash and fiber, and they are free of glucosinolates and other toxic ingredients. The sigma values indicate that the two isolates from rapeseed yield foams more than thrice as stable as foams produced from commercial partially degraded soy protein.
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1~8630~7 Analyses of the amino acid composition of the two isolates show a fairly high lysine content. Isoleucine, which is considered the limiting amino acid in rapeseed meal, occurs at a higher level in the isolates than in the meal used as starting material.
It is clearly demonstrated by this example, that pure, light colored, bland protein isolates having a desirable amino acid composition can be ob*ained from rapeseed (Lesiral at a high yield through a combination of countercurrent extraction and stepwise precipitation.
Ramification of the invention The process described in this invention can be subjected to several modifications in order to suit special requirements.
Thus, more than two protein fractions can be produced by the step-wise addition of a mineral acid to the protein extract whereby the pH value ~i is adjusted to values between 6.5 and 3.0; the various protein isolates pre- -cipitated are filtered off or centrifuged, washed and dried.
In some cases it is possible to modify the process of countercurrent extraction in such a way, that the total proteins are dissolved in a single step or in a multiple stage extraction, either with water, at pH 7.0, or with aqueous solutions of sodium hydroxide or potassium hydroxide, at a pH value between 7.5 and 10Ø
The principle of the process described in this invention can also be applied to the production of proteins from seeds other than rapeseed.
Nutritive value of protein isolates Experiments in chicks ~A.S. El Nockrashy, M. Kiewitt, H.K. Mangold and K.D. Mukherjee, Nutr. Metab. 19, 145-152 ~1975~) revealed better per-formance of the protein isolates as compared to the corresponding meals. Both .
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108630q the feed consumption and weight gain of chicks fed protein isolates were higher than those of chicks that received the corresponding meals. The protein efficiency ratios of diets containing 20 % rapeseed protein varied from 2.2 to 3.4, which indicates that protein isolates from rapeseed are eminently suitable for feeding chicks. In comparison, the meals of soybean, sunflower seed and sesame seed have protein efficiency ratios in chicks of 2.1, 2.1 and 0.85, respectively.
Similar results were obtained in nutritional experiments with rats.
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~08630q isolates are suitable for human consumption as well as animal feed, they can be used to enrich other foodstuff with valuable proteins.
We have found that a maximum of protein present in defatted rape-seed meals can be extracted by a countercurrent process using water or aqueous solutions of electrolytes. In addition, we have discovered, that almost all of the protein present in the extract can be recovered by stepwise precipita-tion with aqueous mineral acid at different pH values.
Description of preferred embodiments The overall process for the preparation of protein isolates from rapeseed consists of two procedures: First, the proteins are extracted by a countercurrent process, continuously or discontinuously, using water, at pH 7.0, or aqueous solutions of sodium hydroxide or potassium hydroxide~ at pH values between 7.5 and 10.0, preferably at pH 9Ø Second, the proteins in the extract are precipitated in two consecutive steps by the addition of a mineral acid, such as hydrochloric acid, to attain a pH value between 5.0 and 6.5, preferably between pH 5.7 and 6.0 (Protein Isolate I), and then a pH value between 3.0 and 4.0, preferably pH 3.6 (Protein Isolate II). The precipitated proteins are washed with water and/or an organic solvent and, after filtration, they are dried in the usual manner.
The major advantages of the countercurrent extraction are, - almost quantitative dissolution (>95%) of protein at - least requirement of sdlvents and chemicals due to optimal utilization of the dissolving capacity of the solvent, - easy adaptibility to either a continuous or discontinuous process, - low space requirement of the plant due to the - small volume of equipment, and also, - low cost of plant, equipment, utilities and operation.
l(~B630q The major advantages of the stepwise precipitation of proteins at different pH values are, - the almost quantitative recovery of proteins from the extract at a minimum of chemicals and energy, - the feasibility of continuous or discontinuous processing, - the availability of two or more distinct types of proteins, - the very high protein content (>95%) of the products isolated~
- the negligible content of glucosinolates in the protein isolates and - the favorable amino acid composition of the protein isolates.
The protein isolates have a light color, bland taste and no odor;
they are suitable for human consumption as well as for various technical applications.
The entire process described in this invention is feasible on a large scale because each of the two procedures involved, - extraction of the proteins from defatted meal as well as precipitation of the proteins from the extract, - can be carried out in a continuous fashion. The overall yield of protein isolates is very high because each of these two procedures results in high recovery. Both the countercurrent extraction and the step-wise precipitation of proteins, as unit processes, contribute to the low cost of the isolation of proteins from rapeseed. The solid residue remaining after extraction of the proteins has a high fiber content and may serve as a filler, whereas the liquid remaining after precipitation, due to its high ; carbohydrate content, may be used in fermentation industry.
In conclusion, the process described constitutes a significant advance in the isolation of proteins from rapeseed. Both the countercurrent extraction of proteins and their stepwise precipitation and certainly, the combination of these processes are entirely new.
- . . : ., ... :
10863~7 The following specific examples illustrate the present invention : more fully. These two examples are for illustrative purposes only and are not ~- intended to limit the scope of the invention.
Example I
Figure 1 is a schematic representation of the countercurrent ex-traction of proteins from defatted oilseeds.
Fresh solvent meal t meal t meal 1 meal Stage A I l ~ J I ~ IV Extract A
Fresh solvent from ~ from t from 1 from Stage B Stage A ~ Stage A ~ Stage A ~ Stage A Extract B
Fresh solvent from ~ from ~ from ~ from Stage C Stage B ~ Stage B ~ Stage B ~ Stage B
Extract C
Fresh solvent from l from ~ from ~ from Stage D Stage C ~ Stage C J Stage C ~ Stage C Extract D
Figure 1: Sche~e for the countercurrent extraction of proteins.
108630q In a typical example, four 250 g samples of hexane-defatted rapeseed meal ~Brassica napus, Erglu), designated I-IV, were extracted with 0.02 M sodium hydroxide. In each of the four stages, A-D, the first sample was extracted with 6250 ml of fresh solvent at a meal to solvent ratio of 1:25. Extraction was carried out at ambient temperature for 10 minutes using a high-speed homogenizer. Subsequently, the samples were filtered under vacuum through cotton cloth. At each stage the filtrate from one sample was used to extract the next sample after measuring its volume and taking aliquots for nitrogen determination. At the beginning of each stage, the first sample in the previous stage was moved to the end of the series. The final extracts from the four stages were combined (pH 9.2), centrifuged at 5000 x g for 15 m mutes, and stored at 5C. Out of the 25 liters of 0.02 M sodium hydroxide used a total of 23 liters of extract was recovered. The results of the countercurrent extraction are presented in Table 1. The percentage of meal nitrogen extracted from the sample was calculated from the total amount of nitrogen of protein extracted up to the stage involved, and the amount of nitrogen originally present in the sample. The percentage of total meal nitrogen extracted at the various stages was calculated from the nitrogen content of protein extracts obtained-from-the four samples, at a given stage, and the amount of nitrogen originally-present in the four samples. The results show that about 94 % of the nitrogen present in the meal is ex-tracted.
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`: 108630q , Table ]: Countercurrent extraction of rapeseed (Brassica napus, Erglu) protein Extraction Sample Meal Nitrogen Total Meal Extracted from Nitrogen Extracted Stage No. the sample at each Stage (%~ (%) .
A I 67.1 II 12.0 III 31.1 rv 26.0 34.1 B II 90.6 III 49.1 IV 48.8 I 71.0 30.8 C III 83.4 IU 81.9 I 82.1 II 93.1 20.3 D IV 97.2 I 92.0 II 94.2 III 91.2 8.6 It is obvious that the countercurrent extraction of proteins as described in the present example offers great advantages over single step extractions-becaus-e of the high degree of protein recovery at a minimum re-quirement of solvent. Anothe~ major advantage of working with more concen-trated suspensions in a countercurrent process is that less material has to be treated for a very high output. The air-dried residue resulting from the countercurrent extraction contained 4.Q % protein and 21.1 % fiber.
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1~8630~7 The combined protein extract (23 liters) was transferred to a pre-cipitation vat. This solution, which contained soluble proteins, carbo-hydrates, minerals and glucosinolates had a pH value of 9.2; it was acidified to a pH value of 6.0 by the addition of 93 ml of 6 N hydrochloric acid in order to precipitate "Protein Isolate I". The protein curd was allowed to settle for about two hours. The supernatent liquid was siphoned off and transferred to another precipitation vat. The precipitated curd was centri-fuged at 5000 x g for 10 minutes and the supernatent was added to the solution in the second vat. The curd was washed with 400 ml of water and the washings were combined with the solution in the vat. The water-washed curd was then leached twice with 400 ml, each, of acetone. The protein isolate was air-dried at room temperature, Protein Isolate I (220 g) is light grey and has a bland taste.
The combined supernatent and the water washings from Protein Isolate I (pH ~.21 were acidified to a pH value of 3.6 by the addition of 103 ml of 6 N hydrochloric acid in order to precipitate "Protein Isolate II".
The protein curd was allowed to settle for 4 hours. The supernatent liquid was siphoned off and discarded. The precipitated curd of Protein Isolate II
was washed once with 200 ml of water and twice with 200 ml of acetone, each.
Protein Isolate II was air-dried at room temperature. Protein Isolate II (77 is white and has a bland taste.
The yields of Protein Isolates I and II and the total yield are as follows:
Protein Isolate I Protein Isolate II Total ~ % % %
Yield65.2 22.9 88.1 ,, , ., . , :.
1~8630q Analyses of the two rapeseed protein isolates are given in Table 2.
Table 2: Analyses of rapeseed ~Brassica napus, Erglu) protein isolates Protein Isolate I Protein Isolate II
Moisture % 10.5 8.1 Protein (dry basis) %
~% protein-N x 6.25) 92.9 98.6 Lipids % o.oo o.oo Ash % 0.70 0.31 Crude fiber % - 0.06 0.02 Glycosinolates % traces traces Static foam (~) 310 395 .
These analytical data show that the protein isolates are of high purity. These isolates conta~n little ash and fiber, and they are free of glucosinolates and other toxic ingredients. The sigma values indicate that the two isolates from rapeseed yield foams more than twice as stable as foams produced from commercial partially degraded soy protein.
Analyses of the amino acid composition of the two isolates show a fairly hîgh lysine content. Isoleucine, which is considered the limiting amino acid in rapeseed meal, occurs at a higher level in the isolates than in the meal used as starting material.
It is cl~early demonstrated by this example that pure, light colored, bland protein isolates having a desirable amino acid composition can be obtain-ed from rapeseed (Erglu) at a high yield through a combination of counter-current extraction and stepwise precipitation.
Example II
The countercurrent extraction (Figure l) described was carried out _ g _ - .. :: . . , ~ ::.:- :,, :. ,. : :: ~ ::: ::, : -108630~7 on a large lot of hexane-defatted rapeseed meal (Brassica napus, Lesira).
Four 1250 g samples were extracted with 0.02 M sodium hydroxide solution using a ~eal to solvent ratio of 1:20. The mixture was filtered under a pressure of three atmospheres. The results of the countercurrent ex-traction are given in Table 3. The percentage of total meal nitrogen extract-ed at each stage was calculated from the amount of nitrogen in the protein extract at the stage involved and the amount of nitrogen origi~ally present in the four samples.
Table 3: Countercurrent extraction of rapeseed (Brassica napus, Lesira) .
1 0 protein Extaction Total Meal Nitrogen Stage Extracted at each Stage ~%) A 49.2 B 27.2 C 14.4 D 1.9 .
These data demonstr~te that even after scaling up the process, a high efficiency of the countercurrent extraction for the dissolution of the protein is obtained. As much as 93 % of the protein-nitrogen present in the meal is thus extracted at a minimum solvent requirement.
The combined extracts from the four stages ~91 liters) were centri-fuged at 5000 x g and transferred to a precipitation vat. The stepwise precipitation process as well as the washing and drying of the precipitated curds were carried out as in Example I. The extract having a pM value of 9.2 was acidified to pH 5.7 by the addition of 391 ml of 6 N hydrochloric acid in -:. ' :: : --1~8630r7 order to precipitate Protein Isolate I. Subsequently, Protein Isolate II was precipitated from the supernatent and washings at a pH value of 3.6 by the addition of 378 ml of 6 N hydrochloric acid. The air-dried Protein Isolate I
~1168 g) is light grey, and the air-dried Protein Isolate II ~287 g) is white.
Both isolates have bland taste.
The yields of Protein Isolates I and II and the total yield are as follows:
Protein Isolate I Protein Isolate II Total ~%) ~%) ~%) - Yield 73.2 18.0 91.2 Analyses of the two rapeseed protein isolates are given in Table 4 Table 4: Analysis of rapeseed (Brassica napus, Lesira) protein isolates . _ _ _ _ Protein Isolate I Protein Isolate II
~oisture % 7 3 7.2 Protein ~dry basis) %
C% protein-N x 6.25) 99.6 99.3 Lipids % traces traces Ash % 0 04 Crude fiber % traces traces Glucosinolates % traces traces Static foam ~) 411 450 These analytical data show that the protein isolates are of high purity. These isolates contain little ash and fiber, and they are free of glucosinolates and other toxic ingredients. The sigma values indicate that the two isolates from rapeseed yield foams more than thrice as stable as foams produced from commercial partially degraded soy protein.
; r~r - 11 ~
1~8630~7 Analyses of the amino acid composition of the two isolates show a fairly high lysine content. Isoleucine, which is considered the limiting amino acid in rapeseed meal, occurs at a higher level in the isolates than in the meal used as starting material.
It is clearly demonstrated by this example, that pure, light colored, bland protein isolates having a desirable amino acid composition can be ob*ained from rapeseed (Lesiral at a high yield through a combination of countercurrent extraction and stepwise precipitation.
Ramification of the invention The process described in this invention can be subjected to several modifications in order to suit special requirements.
Thus, more than two protein fractions can be produced by the step-wise addition of a mineral acid to the protein extract whereby the pH value ~i is adjusted to values between 6.5 and 3.0; the various protein isolates pre- -cipitated are filtered off or centrifuged, washed and dried.
In some cases it is possible to modify the process of countercurrent extraction in such a way, that the total proteins are dissolved in a single step or in a multiple stage extraction, either with water, at pH 7.0, or with aqueous solutions of sodium hydroxide or potassium hydroxide, at a pH value between 7.5 and 10Ø
The principle of the process described in this invention can also be applied to the production of proteins from seeds other than rapeseed.
Nutritive value of protein isolates Experiments in chicks ~A.S. El Nockrashy, M. Kiewitt, H.K. Mangold and K.D. Mukherjee, Nutr. Metab. 19, 145-152 ~1975~) revealed better per-formance of the protein isolates as compared to the corresponding meals. Both .
,,,,, ,, . ,:, ~ " " "; ,: i ~ ' '' ' :':.' .. :, ' '' '`.. : . :
108630q the feed consumption and weight gain of chicks fed protein isolates were higher than those of chicks that received the corresponding meals. The protein efficiency ratios of diets containing 20 % rapeseed protein varied from 2.2 to 3.4, which indicates that protein isolates from rapeseed are eminently suitable for feeding chicks. In comparison, the meals of soybean, sunflower seed and sesame seed have protein efficiency ratios in chicks of 2.1, 2.1 and 0.85, respectively.
Similar results were obtained in nutritional experiments with rats.
.' ~
~1 ' ' . ~.
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for producing protein isolates from rapeseed which comprises - dissolution of the proteins in rapeseed press cakes or defatted rapeseed meals by continuous or discontinuous countercurrent extraction with water, at pH 7.0, or with aqueous solutions of sodium hydroxide or potassium hydroxide at pH 7.5 to 10.0, and - precipitation of two protein fractions from this extract by stepwise addition of mineral acid , to adjust the pH value to 5.0 to 6.5, (Protein Isolate I), and then to pH 3.0 to 4.0, (Protein Isolate II) followed by - washing of the two protein isolates with water and/or an organic solvent, filtration and/or centrifugation and drying.
2. A process according to claim 1 wherein said dissolution with sodium hydroxide or potassium hydroxide is at a pH of 9Ø
3. A process according to claim 1 wherein said mineral acid is hydrochloric acid.
4. A process according to claim 1 wherein said mineral acid adjusts the pH of Protein Isolate I to 5.7 to 6Ø
5. A process according to claim 1 wherein the pH value of Protein Isolate II is 3.6.
6. The process defined in claim 1 in which more than two protein isolates are precipitated from the extract by stepwise addition of an electro-lyte solution to attain several pH values between 6.5 and 3.0, followed by washing of the protein isolates with water and/or an organic solvent, filtration and/or centrifugation and drying.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2540177A DE2540177C3 (en) | 1975-09-10 | 1975-09-10 | Process for obtaining proteins from rapeseed |
| DEP2540177,8,41 | 1975-09-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1086307A true CA1086307A (en) | 1980-09-23 |
Family
ID=5956006
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA260,900A Expired CA1086307A (en) | 1975-09-10 | 1976-09-10 | Process for the isolation of proteins from rapeseed |
Country Status (4)
| Country | Link |
|---|---|
| CA (1) | CA1086307A (en) |
| DE (1) | DE2540177C3 (en) |
| FR (1) | FR2323334A1 (en) |
| SE (1) | SE429186B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2011000094A1 (en) * | 2009-07-02 | 2011-01-06 | Bioexx Specialty Proteins Ltd. | Process for removing organic solvents from a biomass |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DD127952A5 (en) * | 1975-12-02 | 1977-10-19 | Akad Rolniczo Tech | METHOD FOR PRODUCING PROTEIN CONCENTRATE FROM RAPESAMEN AND ARRANGEMENT FOR IMPLEMENTING THE PROCESS |
| US20030124241A1 (en) * | 2001-10-10 | 2003-07-03 | Westdal Paul S. | Animal feed composition |
| NL2029591B1 (en) * | 2021-11-02 | 2023-06-01 | Cano Ela B V | Method for extracting a lipid-, a protein-, and/or a carbohydrate-containing composition from oil-rich seeds |
-
1975
- 1975-09-10 DE DE2540177A patent/DE2540177C3/en not_active Expired
-
1976
- 1976-09-08 SE SE7609919A patent/SE429186B/en unknown
- 1976-09-10 FR FR7627261A patent/FR2323334A1/en active Granted
- 1976-09-10 CA CA260,900A patent/CA1086307A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2011000094A1 (en) * | 2009-07-02 | 2011-01-06 | Bioexx Specialty Proteins Ltd. | Process for removing organic solvents from a biomass |
Also Published As
| Publication number | Publication date |
|---|---|
| SE7609919L (en) | 1977-03-11 |
| FR2323334B1 (en) | 1980-03-28 |
| FR2323334A1 (en) | 1977-04-08 |
| SE429186B (en) | 1983-08-22 |
| DE2540177B2 (en) | 1978-08-24 |
| DE2540177A1 (en) | 1977-03-17 |
| DE2540177C3 (en) | 1979-07-26 |
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