SE440588B - WAY TO MAKE A VEGETABLE PROTEIN EXTRACT - Google Patents

Description

fvsoasaz-S soluble carbohydrates, salts and organic compounds bound to the proteins. Among these, phytic acid (amio-inositol-hexaphosphoric acid) constitutes 1.5-2% of the dry matter.

To obtain a concentrate, a process consists in washing the defatted flour with water or an aqueous solution at the isoelectric pH value, and the protein-rich residue is separated from the supernatant liquid phase. The dry matter in this residue consists of 70% protein and 20% insoluble polysaccharides, as well as salts and organic compounds, among these 1.2-1.7% phytic acid. The protein content further contains in these two cases biologically active proteins, among others then trypsin inhibitor in a non-negligible amount. However, the presence of these two compounds, the phytic acid and the trypsin inhibitor, has a negative effect on the nutritional value of the protein extract. In practice, the trypsin inhibitor may be a cause of hypertrophy of the pancreas, and it may also be the cause of a decrease in the growth rate of young rats. The phytic acid, in turn, can form complexes with a number of vital metal cations, such as calcium, iron, magnesium and zinc, and reduces their availability and resorption in the intestine.

The present invention minimizes these disadvantages, since in a particularly simple and elegant manner it enables the production of vegetable protein extracts which at the same time have low levels of phytic acid and trypsin inhibitor, as well as of oligosaccharides. The invention relates to a method of preparing such an extract, wherein: in a first embodiment, which is particularly suitable for obtaining isolates, a vegetable flour is suspended in an alkaline medium with a pH between 7 and 14 or in an acidic medium. with a pH between 1 and 3.5, after which from the resulting soluble fraction the protein extract is precipitated and isolated from the precipitation medium. This embodiment is characterized in that the protein extract precipitates at a pH which is in a range, 3 to 5.7. A second embodiment consists in that a flour, a concentrate or an isolate is washed with an aqueous medium, and that after separation of the washing waters the insoluble proportion is recovered, which forms the vegetable protein extract. This embodiment is characterized in that the aqueous medium has a pH which is within the range defined above.

In this way, a protein or isolate depleted in phytic acid and trypsin inhibitor is obtained as a protein extract, depending on whether the starting material subjected to the washing constitutes a flour or a concentrate, resp. an isolate.

In other words, the method according to the invention differs from the previously known processes in that the pH value at which the work was carried out does not constitute the isoelectric pH value, but a significantly higher pH value, which results in a very small reduction of the quantitative the yield, ie by the amount of proteins extracted, which, however, is largely and more than offset by the surprising improvement in the quality of the proteins.

The isoelectric pH value "ISO" refers to the isoelectric pH value of the protein under consideration. In practice, since it is a mixture of proteins, "ISO" denotes the average value of isoelectric pH values which is characterized by a minimum solubility. This pH is located at 4.5 for the majority of the vegetable crude proteins (for example soy and cotton), ie those which have not been subjected to any special treatment other than solubilization. The pH range considered thus ranges from 5.3 to 5.7, and preferably then from 5.3 to 5.5.

It has been generally shown that the quantitative yield decreased by 10-20%, but that the levels of phytic acid and trypsin inhibitor were reduced by a factor of 2-4, depending on the pH value used.

The content of oligosaccharides is also reduced.

It should be noted here that protein extracts with a low content of at least one of these undesirable substances have already been prepared, but at the cost of enzymatic treatments or complicated technical treatments, such as ultrafiltration, or also by incubating the starting material for long periods at temperatures above room temperature. The difference is thus large compared to the simplicity of the process according to the invention.

In a well-known manner, they are vegetable materials from which valuable protein extracts can be extracted from plants, such as soybean, sunflower, corn, broad bean, lime bean, ricin, cottonseed, croton, lupine, sesame, peanuts, vigna sinensís. chickpeas, etc. 40 7808342-5 and consist generally of pea plants and oilseeds. The flours, preferably degreased, used as starting materials have been defined above in the introductory part of the present description, as well as the concentrates or isolates intended to be treated by washing. It should be noted that these are later conventionally recovered at the isoelectric pH value.

The pH value, which should be between 5.3 and 5.1, preferably between 5.5 and 5.7, can be adjusted in part by any suitable reagent, for example hydrochloric acid, phosphoric acid or acetate buffers, or also sodium hydroxide, potassium hydroxide or carbonate buffers. depending on the circumstances. The pH value is the decisive feature which makes it possible to obtain the desired protein extract in quantity and quality. For soybeans, for example, the levels of phytic acid and trypsin inhibitor are hardly reduced at pH below 5.0, while at pH above 5.7 the quantitative losses become too great and the levels of trypsin inhibitor again become unfavorable.

The implementation of the method according to the invention does not require any special plant, nor any expensive reactant or treatment, or any modification of already existing production lines. D f The separation of soluble and insoluble proportions can be carried out in a conventional manner by filtration, decantation, centrifugation or any other procedure. Of course, the resulting insoluble fractions can be washed with water, or suitably with an aqueous solution having a pH between 5.3 and 5.71.

The protein extracts can be used as such or after neutralization, if required after standardization of their composition. They can also be dried by spray drying, freeze-drying, etc. They can be used as food, especially for humans, and especially then as a dietary food. Their nutritional value is significantly improved.

In the following examples, the implementation of the method according to the invention in the two embodiments is illustrated. In these examples, the percentages are by weight, and the values according to the invention are marked with an asterisk in the comparison tables.

Example 1 'Soybean concentrate 7 Starting from a defatted soybean meal which is freed from the skin, concentrate is prepared by suspending this flour in water in an amount of 100 g of flour to 1900 g of distilled water.

This suspension is stirred at room temperature for one hour, after which 6 equal fractions of 300 g each are taken out, and the pH is adjusted to 4.5, 5.0, 5.5, 5.5, 5 with hydrochloric acid. 7 and 6.0. These fractions are then centrifuged at 3000 g for 15 minutes, and the bottoms from the centrifugation are dried by freeze-drying. The amount and composition of these dried fractions are given in the following table.

Amount of starting product: 15 g per experiment, Q | .

Reached pH after ~ *! * »* | * In acidification 4.5 5.0 1 5.3 5.5 ~ 5.7 »6.0 Amount of dried product 10.4 g 10.0 g 9.7 g 9.2 g 8.5 g 7 , 3 g Nitrogen amount. 1.22 go 1.18 go 1.16 g 1.10 g 1.00 g. 0.57 g _ Protein content 73.0% 73.7% š 74.3% 74.3% 73.7% 48.8% i l l Content of phytin- I 1 g acid _ 1.49%; 0.97% f 0.75% 0.67% 0.64% 0.50% - 1 i '1 Content of trypsin- β, inhibitor (arbite- I 3 I g units per f; - - f * 3 mg nitrogen) 370 ¿295 2 225 I 185 I 190 244.

It is clear that the concentrates prepared at a pH between 5.0 and 5.7 are better than those prepared at pH 4.5, without, however, the yield losses becoming too great, as at pH 6.0.

Example 2 Soy isolate (by washing) and soy concentrate g of the products listed below are subjected to a wash with water at pH 5.5 in an amount of 25-100 g of water to 5 g of product. The suspension thus obtained is centrifuged at 3000 g for 15 minutes, and the insoluble material is collected and dried. 7808342-5 6 Content of fztinsvra Obtained 1 From the beginning 1 Weight of obtained in insoluble product 1 Starting protein- Protein content 1 products ï Experimental isolate (PH 4,5) 8,95 g 96,9 _ fi b 1,20% 1 , 84% Commercial isolate of ® Prornin R) 95,0 o \ ° 1,13 = \ ° ._ \ v .ß G e, e Experimental compound (pH 4,5) u '~ °' 66,5 0 , 89% Commercial - concentrate 1 @ §Dæ @ ro} D. ._. .-.....__....... ... m __...

Example 5 Soy isolate (by precipitation) Starting from a defatted and peel-free soy flour, isolate is prepared by suspending 100 g of flour in 1900 g of water, after which the pH is adjusted to 8.0 by means of sodium hydroxide.

This suspension is centrifuged for 15 minutes at 3000 g to give 1740 g of a solution containing 90% of the flour. Then 6 equal fractions of 280 g are prepared, in which of the proteins from the proteins were precipitated by adding hydrochloric acid to pH values of 4.5, 5.0, 5.5, 5.3, 5.7 and 6.0. These fractions are then centrifuged at 3000 g for 15 minutes, and the precipitates from the centrifugation are collected and lyophilized. The results are given in the same way as in Example 1.

Amount of starting product: 16 g per experiment. 1 1 f 1 v: 1: | 1- in 9: pH after acidification 4.5 5 5.0; 5.3 š 5.5 § 5.7 I 6.0 Ingredient of dried 3 É ¿É 1 g, 1 product '6.25 g; 6.15 g 5.5 g É 5.25 g I 5.1 g 1.55 g 'i 1 i 1 s 1 f; ß fi ngd of nitrogen E 0.92 g; 0.90 go 0.82 g 0.76 g E 0.72 g 5 0.20 g, .-! v 1 Prøceinhalt 1 92.0% í 91.4 11 93.2 51 90.5 9; 88.5 8 É 80.6 1 1 1 '1 1 I I é Content of fyric acid 2.03 9, 1.14 8; 0.82% g 0.68 9 1 0.58 9 ¿0.76 8 E ï i 1 _ 'E fmnrfnmmnnmr- I 1 1 j bits (arbitrary I 1 units per mg. Nitrogen 1' 375 225 1 205 155 160 The quality of the isolates obtained between pH 5.0 and .7 is clear, as with the concentrates in Example 1.

Example 4 Isolates of soy, sesame, peanut and chickpeas (by precipitation) a) A commercial, defatted soybean meal Kß; Baker's Nutrisoy, from Archer Daniel Midlands), which is slightly pretreated with heat and therefore has a high solubility index for nitrogen, is suspended at pH 8.0 in an amount of 60 g of flour to 540 g of water. After removal of the insoluble matter by centrifugation, half of the liquid phase is acidified to pH 4.5 and the other half to pH 5.5. (b) The same procedure is carried out on another commercial, defatted soybean meal (ß Soyafluff ZOOW from Central Soya). The results are qualitatively similar to those from Example 4a, but since this flour has been heat-treated more strongly, lower quantitative yields are obtained. c) The procedure is also applied to a sesame flour. The decrease in phytic acid content is clear, despite the very low solubility of the starting material. g d) The procedure is also successfully applied to a defatted peanut meal. The amount of protein recovered in this case is the same at the two pH values. e) The procedure is also applied to ground chickpeas. The reduction in phytic acid content is also indisputable there.

Example Starting: Precipitated pro- ï Phytic acid- Precipitated pro-, Phytic acid product at pH 4,5; halt tein vid 2 rahalt; pH 5.5> \ 1 4a (R Bakers 8.3 g ¿2.2 t, 6.4 g 0.77 e, Nutrisoy. 4b KB'Soyafluff Ä _ zoow, 6.4 g 2.2 2, 4 .5 g 0.88%; fz 4c Sesame; 1.12 g 2.9% 2 1.05 g 0.86% 2 V å _ f 4d Peanuts f 13.4 g _ 1.6% i 13.6 g - 0.70% š ii, 4e Chickpeas _ 3.5 gf 1.5% I 5.0 g 0.44%. '!' Example 5 Soy isolate (by precipitation) kg of defatted soy flour is suspended in 95 kg of water, after which The pH is adjusted to a value of 8.2 and the insoluble material 78083l12-5's is separated by centrifugation in an apparatus of Alfa D Laval.The recovered liquid, which contains 85 ß of the total amount of nitrogenous material from the soybean meal, is then acidified to pH 5. 5, mixed to facilitate precipitation and centrifuged in the same apparatus as before, the residue being collected and lyophilized.

This gives 1.55 kg of isolate with 92.9% protein content, ie 66% of the total amount of nitrogen-containing material from the soy flour. This isolate contains 0.61% phytic acid and 96 units of trypson inhibitor (determined according to Kakade et coll., Cereal Chem. Eel, 376 (1974)) per mg of nitrogen. - Its PER value (protein efficiency ratio, in relation to a standard for casein with PER = 3.2) is 2.18, which value increases to 2.66 after a heat treatment for 10 minutes at 100 ° C.

In comparison, an isolate prepared under identical conditions by acidification to pH 4.5 yields 4.5 tea, ie 78% contains 1.8% phytic acid and 350 units trypsin inhibitor (according to 2.26 kg pro- of the nitrogen-containing material of soybean meal. - Kakade et coll) per mg nitrogen. Its PER value is only 1.66, and after a heat treatment for 10 minutes at 100 ° C it does not exceed 2.11.

A commercial isolate of (R promine R has a PER value of 1.1, and 1.7 after heating under the above conditions.

Example 6, Soybean and peanut isolate (by precipitation) a) The preparation procedure described in Example 4a is repeated, but with the difference that the defatted soybean meal (60 g) is suspended in an aqueous medium of sodium hydroxide to give a final pH of 12.0. After removal of the insoluble material by centrifugation, half of the liquid phase is sucked to pH 4.5, and the other half to pH 5.5. b) The preparation of a peanut isolate described in Example 4d is repeated under the pH conditions described above, namely 11.5. After removal of insoluble matter by centrifugation, half of the liquid phase is acidified to pH 4.5 and the other half to pH 5.5. 9 78Û8342 ~ 5 l Example Starting Proteins ut- Phytic acid- ~ Proteins Phytinsy-t li product precipitated at, he auf-amg embrace 1 pH 4.5 i at pH 5.5 l I .ÅVfFGttat aa sojamjan 11.0 g 0.531 , 11.1 g. o, 14% Degreased É Él peanut ~ 1 § 1 eb flour 15.0 g 1.4: 1, 12.4 gf 0.41 i - In a comparison, the content of trypsin inhibitor in the soy isolate is at pH 5, 5 from Example 6a 229 units, compared to 375 units for the isolate prepared under the same conditions, but precipitated at pH 4.5.

Example 7 Soy and peanut isolate (by precipitation) a) The preparation described in Example 4a is repeated, but with the difference that the defatted soy flour is suspended in an aqueous medium of hydrochloric acid to obtain a pH of 2.5. After removal of insoluble material by centrifugation, half of the liquid phase is acidified to pH 4.5, and the other half to pH 5.5. g b) The preparation of a peanut isolate described in Example 4d is repeated under the pH conditions described above, i.e. at 2.5. After removal of insoluble material by centrifugation, half of the liquid phase is acidified to pH 4.5, and the other half to pH 5.5.

Example Starting I Proteins precipitated 2 Phytic acid- Protein Phytic acid ~ 7 product E precipitates at in content 'precipitated crude content _ pH 4,5 at pH 5.5 1 å Degreased in 7a soy fi beer 8.9 g 1,' 5% 8, 2 g 0.69% 1 s Å. Degreased - peanut §, 7b n 'beer' 7.3 g 1 1.35% 7.3 g 0.77% In addition, the content of trypsin inhibitor is 242 units of the soy isolate from Example 7a when precipitated at pH 5.5 zaoszaz-s 1, against 443 units when precipitated at pH 4.5.

Example 8 Soy isolate (by precipitation), The bar preparation procedure of Example 6a is repeated on a larger scale, starting from 10 kg of defatted soy flour, suspended in an aqueous medium of sodium hydroxide to give a final pH of 11.5.

After removal of insoluble material, 4.0 kg of soy isolate are obtained by precipitation n at pH 5.5, which contains 1 kg of proteins and has a phytic acid content of 0.18%.

Example 9 I Complete soy isolate (by precipitation) In 190 g of water, 10 g of peeled and ground soybeans are suspended, after which the pH of the suspension is adjusted to 8.0. Insoluble material is then removed by centrifugation at 2000 g for 10 minutes. Those at the surface separated. the fatty materials are added to the solution obtained after centrifugation, the pH of which is adjusted to 5.5. The precipitate obtained (4 g after drying) is an isolate containing only 0.32% 62% dry matter. phytic acid at a protein content of of the total dry matter content, ie about 83% of fat-free. By comparison, precipitation at pH 4.5 gives 4.9 g of isolate containing 57% proteins of the total dry matter, and 1.32% of Example 10. Whole soy concentrate phytic acid.

A whole soy concentrate is prepared by suspending 10 g of peeled and ground whole soybeans in 190 g of water, after which the pH is adjusted to 5.5. The insoluble material is then separated by centrifugation at 2000 g for 10 minutes, and the fat material from the liquid phase is added to the bottom batch from the centrifugation. After drying, a whole soy concentrate (6 g) is obtained, which contains 51% proteins of the total amount of D dry matter, ie 68 a D of fat-free dry matter, and 0.31 a of phytic acid.

Claims (7)

'78083 # 2 “5 11 Patent Claims A process for preparing a vegetable protein extract starting from an aqueous medium containing it, characterized in that the vegetable protein extract in solid form is separated from the aqueous medium after the pH value thereof has been adjusted by a value of 5.3-5.7. A method according to claim 1, wherein a vegetable flour is suspended in an alkaline medium having a pH between 7 and 14, or in an acidic medium having a pH between 1 and 3.5, after which starting from the soluble proportion obtained , the protein extract is precipitated and isolated from the precipitating medium, characterized in that the extract is precipitated at a pH of 5.3-5.7. 3. A method according to claim 2, characterized in that the vegetable flour consists of a flour of pea plants or oil plants. 4. A method according to claim 2, characterized in that the vegetable flour consists of a flour of soybeans, sunflower seeds, maize, broad beans, lima beans, ricin, cotton seeds, croton, lupine, sesame seeds, peanuts, gooseberries or carrots. A method according to claim 1, wherein with an aqueous medium a flour, a concentrate or an isolate is washed, and after separation of the washing waters the insoluble material is recovered, which forms the vegetable protein extract, characterized in that the aqueous medium has a pH value of 5.3-§f7. 6. A method according to claim 5, characterized in that the flour, concentrate or isolate consists of a flour, a concentrate or an isolate of pea plants or oil plants. 7. A method according to claim 5, characterized in that the flour, concentrate or isolate consists of a flour, a concentrate or an isolate of soybeans, sunflower seeds, maize, broad bean, lima bean, ricin, cotton seeds, croton, lupine, sesame seeds. , peanuts, vignas or chickpeas.