HK1158898A - Preparation of canola protein isolate from canola oil seeds ( "blendertein" ) - Google Patents

Description

Preparation of canola protein isolate from canola oil seed ("BLENDETIEIN")

Reference to related applications

This application claims priority from U.S. provisional patent application No. 61/136,192 filed on 8/18 of 2008 as filed on 35 USC 119 (e).

Technical Field

The present invention relates to the preparation of canola protein isolate.

Background

In the processing of canola oil seeds, the seeds are crushed to remove a substantial portion of the canola oil component of the seeds. The remaining crushed seeds are subjected to solvent extraction, typically using hexane, to extract the remaining part of the oil. The solvent is then recovered for reuse to produce canola oil seed meal (meal).

Canola oil seed protein isolates having a protein content of at least 100 wt% (N x 6.25.25) may be formed from oil seed meal by methods such as described in co-pending U.S. patent application No. 10/137,391 (U.S. patent application publication nos. 2003-0125526 a1 and WO 02/089597) filed on 5/3/2002 and U.S. patent application No. 10/476,230 (U.S. patent application publication No. 2004-0254353 a 1) filed on 6/9/2004, which are assigned to the assignee hereof and the disclosures of which are incorporated herein by reference. The procedure involves a multi-step process comprising extracting canola oil seed meal with an aqueous salt solution, separating the resulting aqueous protein solution from residual oil seed meal, increasing the protein concentration of the aqueous solution to at least about 200 g/L by using a selective membrane technique while maintaining the ionic strength substantially constant, diluting the resulting concentrated protein solution into chilled water to promote the formation of protein micelles, allowing the protein micelles to settle to form amorphous, sticky, gelatinous, gluten-like protein micelles (PMM), and recovering the protein micelles having a protein content of at least about 100 wt% (N x 6.25.25) from the supernatant. As used herein, protein content is determined on a dry weight basis. The recovered PMM may be dried.

In one embodiment of the process, the supernatant from the PMM settling step is processed to recover the canola protein isolate from the supernatant. This procedure can be achieved by initially concentrating the supernatant using ultrafiltration membranes and drying the concentrate. The resulting canola protein isolate has a protein content of at least about 90 wt%, preferably at least about 100 wt% (N x 6.25.25).

The procedure described in U.S. patent application No. 10/137,391 is a substantially batch procedure. In co-pending U.S. patent application No. 10/298,678 (WO 03/043439), assigned to the assignee hereof and the disclosure of which is incorporated herein by reference, filed 11/19/2002, a continuous process for preparing a canola protein isolate is described. In accordance therewith, canola oil seed meal is continuously mixed with an aqueous salt solution, the mixture is conveyed through a pipe while extracting protein from the canola oil seed meal to form an aqueous protein solution, the aqueous protein solution is continuously conveyed by selective membrane operation to increase the protein content of the aqueous protein solution to at least about 50 g/L while maintaining the ionic strength substantially constant, the resulting concentrated protein solution is continuously mixed with chilled water to facilitate formation of protein micelles, and the protein micelles are continuously allowed to settle while the supernatant continuously overflows until a desired amount of PMM has accumulated in a settling vessel. The PMM is recovered from the settling vessel and may be dried. The PMM has a protein content of at least about 90 wt% (N x 6.25.25), preferably at least about 100 wt%. The overflow supernatant may be processed to recover canola protein isolate therefrom, as described above.

Applicants are aware of procedures for recovering various proteins from oilseeds in which the oilseeds are ground and subsequently processed to recover the proteins. Representative examples are U.S. patent nos. 2,762,820 and 4,151,310. Canola is not among the oilseeds processed in such prior art procedures.

Canola is also known as rapeseed or oilseed rape.

Summary of The Invention

In the process of the present invention, the initial oil removal step typically performed on canola oil seeds is omitted. In accordance with one aspect of the present invention, there is provided a process for preparing a canola protein isolate from canola oil seeds, which comprises:

the canola oil seed is ground,

extracting the ground canola oil seeds with an aqueous extraction medium to solubilize canola protein in the ground canola oil seeds to form an aqueous canola protein solution,

separating the aqueous canola protein solution from the residual ground canola oil seeds,

defatting the aqueous solution of canola protein,

clarifying the defatted canola protein aqueous solution,

concentrating the clarified aqueous canola protein solution while maintaining the ionic strength substantially constant to form a concentrated canola protein solution,

optionally diafiltering the concentrated canola protein solution,

optionally pasteurizing the optionally diafiltered and concentrated canola protein solution,

diluting the concentrated canola protein solution into cold water to promote the formation of canola protein micelles,

collecting the canola protein micelles as protein micellar mass,

drying the protein micellar mass to form a canola protein isolate having a protein content of at least about 90 wt% (N x 6.25.25) d.b., preferably at least about 100 wt% d.b., and

optionally processing the supernatant from the collection of protein micelles to form a further canola protein isolate having a protein content of at least about 90 wt% (N x 6.25.25) d.b., preferably at least about 100 wt% d.b..

The procedure herein for recovering canola protein isolate from canola oil seed is superior to the process for recovering canola protein isolate according to the above process in that the starting material is residual meal from processing canola oil seed primarily for the purpose of recovering oil from the seed, since here a higher quality product is obtained in terms of the color of the isolate, i.e. less pigment formation.

Canola protein isolates produced according to the processes herein may be used in conventional applications of protein isolates, such as protein fortification of processed foods and beverages, emulsification of oils, bodymakers (body formers) in baked goods and foaming agents in gas-entrapped products. In addition, the canola protein isolate may form protein fibers useful in meat analogs, and may be used as an egg white substitute or extender in food products in which egg white is used as a binder. Canola protein isolates may be used as nutritional additives. Other uses of canola protein isolate are in pet foods, animal feed, as well as in industrial and cosmetic applications and in personal care products.

General description of the invention

In the present invention, whole canola oil seeds are ground to provide ground canola oil seed pieces. The initial step of the process of providing canola protein isolate from ground canola oil seed pieces involves solubilizing proteinaceous material from ground canola oil seeds. Alternatively, the seeds may be wet milled using any convenient equipment, such as a high shear pump, to simultaneously grind the seeds and solubilize the proteins. The proteinaceous material recovered from canola seed may be a protein naturally occurring in canola seed, or the proteinaceous material may be a protein modified by genetic manipulation but possessing the characteristic hydrophobic and polar properties of the native protein.

Protein solubilization is most effectively achieved by using a food grade salt solution because the presence of salt enhances the removal of soluble protein from the crushed canola oil seeds. Non-food grade chemicals may be used when the canola protein isolate is intended for non-food use. The salt is typically sodium chloride, although other salts such as potassium chloride may also be used. The salt solution has an ionic strength of at least about 0.05, preferably at least about 0.10, to enable solubilization of substantial amounts of protein. As the ionic strength of the salt solution increases, the degree of solubilization of protein in the canola oil seed initially increases until a maximum value is reached. Any subsequent increase in ionic strength does not increase total protein solubilized. The ionic strength of the food grade salt solution that contributes to maximum protein solubilization varies depending on the salt concerned.

It is generally preferred to utilize an ionic strength value of less than about 0.8, and more preferably a value of from about 0.1 to about 0.15, in view of the greater degree of dilution required for protein precipitation as ionic strength increases.

In a batch process, salt solubilization of the protein is achieved at a temperature of about 5 ℃ to about 75 ℃, preferably with agitation to reduce solubilization time, which is typically about 10 to about 60 minutes. Solubilization is preferably effected to extract as much protein from the canola oil seed meal as is substantially practicable, so as to provide overall high yield.

The lower temperature limit of about 5 ℃ is chosen because below this temperature dissolution is impractically slow, while the upper preferred temperature limit of about 75 ℃ is chosen due to the denaturation temperature of some of the proteins present.

In the continuous process, the extraction of protein from canola oil seed is performed in any manner consistent with achieving continuous extraction of protein from canola oil seed. In one embodiment, the crushed canola oil seeds are continuously mixed with a food grade salt solution and the mixture is transported through a pipe or conduit having a length sufficient to achieve the desired extraction in accordance with the parameters described herein and a residence time sufficient to achieve the desired extraction in accordance with the parameters described herein at a flow rate sufficient to achieve the desired extraction in accordance with the parameters described herein. In such a continuous procedure, the salt solubilization step is effected rapidly in up to about 10 minutes, preferably to effect solubilization to extract as much protein from the canola oil seed as is substantially practicable. Dissolution in a continuous procedure is achieved at a temperature of from about 10 ℃ to about 75 ℃, preferably from about 15 ℃ to about 35 ℃.

The food grade brine solution generally has a pH of from about 5 to about 6.8, preferably from about 5.3 to about 6.2, and the pH of the brine solution can be adjusted to any desired value within the range of from about 5 to about 6.8 for use in the extraction step by using any convenient acid (typically hydrochloric acid) or base (typically sodium hydroxide) as needed.

The concentration of ground canola oil seed in the food grade salt solution during the solubilization step may vary widely. Typical concentration values are about 5 to about 25% w/v.

The protein extraction step using a saline solution has the additional effect of solubilizing the fat present in the canola seeds, which then results in the fat being present in the aqueous phase.

The protein solution resulting from the extraction step generally has a protein concentration of about 3 to about 40 g/L, preferably about 10 to about 30 g/L.

The aqueous salt solution may comprise an antioxidant. The antioxidant may be any convenient antioxidant, for example sodium sulfite or ascorbic acid. The amount of antioxidant employed may vary from about 0.01 to about 1 wt% of the solution, preferably about 0.05 wt%. Antioxidants are used to inhibit the oxidation of phenols in protein solutions.

The aqueous phase resulting from the extraction step may then be separated from the residual canola seed material in any convenient manner, for example by employing a decanter centrifuge followed by disc centrifugation to remove residual seed material. The separated residual seed material may be dried for disposal or further processing.

The fat present in the aqueous canola protein solution may be removed by procedures such as those described in U.S. Pat. nos. 5,844,086 and 6,005,076, which are assigned to the assignee hereof and the disclosures of which are incorporated herein by reference.

As described herein, the aqueous canola protein solution may be cooled to a temperature of about 3 ℃ to about 7 ℃ to facilitate separation of fat from the aqueous phase for removal by any convenient procedure, for example by decantation. Alternatively, the fat may be removed at higher temperatures by centrifugation using a cream separator. Once the fat has been removed, the aqueous canola protein solution may be further clarified by filtration. Canola oil recovered from the aqueous canola protein solution may be processed for use in commercial applications of canola oil.

Alternatively, the aqueous canola protein solution may be separated from the oil phase and the residual canola seed material simultaneously by any convenient procedure, for example using a three-phase decanter. The aqueous canola protein solution may then be further clarified by filtration.

The colour of the final canola protein isolate may be improved in terms of light colour and less strong yellow by mixing powdered activated carbon or other pigment adsorbent with the aqueous solution of the isolated protein and then conveniently removing the adsorbent by filtration to provide a protein solution. Diafiltration may also be used for pigment removal.

Such a pigment removal step may be carried out under any convenient conditions, typically at ambient temperature of the separated aqueous protein solution, using any suitable pigment adsorbent. For powdered activated carbon, an amount of about 0.025% to about 5% w/v is employed, preferably about 0.05% to about 2% w/v.

As an alternative to extracting the ground canola oil seeds with an aqueous salt solution, such extraction may be carried out using water alone, although the use of water alone tends to extract less protein from the ground canola oil seeds than the aqueous salt solution. When such an alternative is employed, the salt may be added to the protein solution at the concentrations discussed above, subsequently after separation from the residual ground oilseed, to maintain the protein in solution during the concentration step described below. When the first fat removal step is performed, salt is typically added after such operation is complete.

Another alternative procedure is to extract the ground canola oil seed with a food grade salt solution at a relatively high pH in excess of about 6.8, typically up to about 9.9. The pH of the food grade salt solution may be adjusted in pH to the desired alkaline value by using any convenient food grade alkali, such as aqueous sodium hydroxide. Alternatively, the ground oilseeds may be extracted with a salt solution at a relatively low pH below about pH 5, typically down to about pH 3. When such an alternative is employed, the aqueous phase resulting from the ground oilseed extraction step is then separated from the residual canola seed material, in any convenient form, as previously discussed. The separated residual canola oil seed material may be dried for disposal or further processing.

The aqueous protein solution resulting from the high or low pH extraction step is then subjected to pH adjustment, as discussed above, to a range of from about 5 to about 6.8, preferably from about 5.3 to about 6.2, prior to further processing as discussed below. Such pH adjustment may be effected, where appropriate, using any convenient acid (typically hydrochloric acid) or base (typically sodium hydroxide).

The aqueous canola protein solution is concentrated to increase its protein concentration while maintaining its ionic strength substantially constant. Such concentration is generally achieved to provide a concentrated protein solution having a protein concentration of from about 50 to about 250 g/L, preferably to about 200 g/L.

The concentration step may be achieved in any convenient manner consistent with batch or continuous operation, for example by employing any convenient selective membrane technique, such as ultrafiltration or diafiltration, using a membrane, such as a hollow fibre membrane or spiral wound membrane, having a suitable molecular weight cut-off, for example from about 3,000 to about 100,000 daltons, preferably from about 5,000 to about 10,000 daltons, taking into account the different membrane materials and configurations, and for continuous operation, sized to allow the desired degree of concentration as the aqueous protein solution passes through the membrane.

As is well known, ultrafiltration and similar selective membrane techniques allow low molecular weight species to pass through while preventing higher molecular weight species from passing through. The low molecular weight species include not only the ionic species of the food grade salt, but also low molecular weight materials extracted from the source material, such as carbohydrates, pigments, and anti-nutritional factors, as well as any low molecular weight forms of protein. The molecular weight cut-off of the membrane is generally selected to ensure that a substantial proportion of the protein remains in solution, while allowing contaminants to pass, taking into account the different membrane materials and configurations.

The concentrated protein solution may then be subjected to a diafiltration step using a saline solution of the same molar concentration and pH as the extract solution. Such diafiltration may be effected using from about 2 to about 20 volumes of diafiltration solution, preferably from about 5 to about 10 volumes of diafiltration solution. In the diafiltration operation, further amounts of contaminants are removed from the aqueous canola protein solution by passage through the membrane together with the permeate (permeate). The diafiltration operation may be effected until no significant further amounts of contaminants and visible colour are present in the permeate. Such diafiltration may be effected using the same membrane as used for the concentration step. However, if desired, the diafiltration step may be effected using separate membranes having different molecular weight cutoffs, for example membranes having a molecular weight cutoff in the range of about 3,000 to about 100,000 daltons, preferably about 5,000 to about 10,000 daltons, taking into account different membrane materials and configurations.

The antioxidant may be present in the diafiltration media during at least part of the diafiltration step. The antioxidant may be any convenient antioxidant, for example sodium sulfite or ascorbic acid. The amount of antioxidant employed in the diafiltration media depends on the material employed and may vary from about 0.01 to about 1 wt%, preferably about 0.05 wt%. The antioxidant serves to inhibit oxidation of phenolics present in the concentrated canola protein isolate solution.

The concentration step and diafiltration step may be effected at any convenient temperature, generally from about 20 ℃ to about 60 ℃, preferably from about 20 ℃ to about 30 ℃, and for a period of time to achieve the desired degree of concentration. The temperature and other conditions used for some degree depend on the membrane equipment used to achieve solution concentration and the desired protein concentration.

As described in U.S. Pat. nos. 5,844,086 and 6,005,076, a further defatting operation may be performed on the concentrated and optionally diafiltered protein solution, if desired.

The concentrated and optionally diafiltered protein solution may be subjected to a color removal operation as an alternative to the color removal operation described above. Powdered activated carbon as well as Granular Activated Carbon (GAC) may be used herein. Another material that may be used as a color absorber is polyvinylpyrrolidone.

The colour absorber treatment step may be carried out under any convenient conditions, typically at ambient temperature of the canola protein solution. For powdered activated carbon, amounts of about 0.025% to about 5% w/v may be used, with about 0.05% to about 2% w/v being preferred. When polyvinylpyrrolidone is used as the color absorbing agent, an amount of about 0.5% to about 5% w/v, preferably about 2% to about 3% w/v, may be used. The colour absorbing agent may be removed from the canola protein solution by any convenient means, for example by filtration.

The concentrated and optionally diafiltered canola protein solution resulting from the optional color removal step may be pasteurized to reduce microbial load. Such pasteurization may be accomplished under any desired pasteurization conditions. Generally, the concentrated and optionally diafiltered canola protein solution is heated to a temperature of about 55 ℃ to about 70 ℃, preferably about 60 ℃ to about 65 ℃, for about 10 to about 15 minutes, preferably about 10 minutes. The pasteurized concentrated canola protein solution may then be cooled for further processing as described below, preferably to a temperature of about 25 ℃ to about 40 ℃.

Depending on the temperatures employed in the concentration step and optional diafiltration step, and whether or not the pasteurization step is effected, the concentrated protein solution may be heated to a temperature of at least about 20 ℃, and up to about 60 ℃, preferably about 25 ℃ to about 40 ℃, to reduce the viscosity of the concentrated protein solution to facilitate performance and micelle formation in the subsequent dilution step. The concentrated protein solution should not be heated above a temperature above which micelle formation does not occur upon dilution with cold water.

The concentrated protein solution resulting from the concentration step and optional diafiltration step, optional color removal step, optional defatting step and optional pasteurization step is subsequently diluted to achieve micelle formation by adding the concentrated protein solution to a body of water having the volume required to achieve the desired degree of dilution. The degree of dilution of the concentrated protein solution may vary depending on the proportion of canola protein desired to be obtained by the micellar route and the proportion from the supernatant. Generally, with lower dilution levels, a greater proportion of canola protein remains in the aqueous phase.

When it is desired to provide the maximum proportion of protein by the micellar route, the concentrated protein solution is diluted from about 5-fold to about 25-fold, preferably from about 10-fold to about 20-fold.

The body of water into which the concentrated protein solution is injected has a temperature of less than about 15 ℃, typically from about 3 ℃ to about 15 ℃, preferably less than about 10 ℃, because of the improved yield of protein isolate in the form of protein micro-agglomerates obtained with these cooler temperatures at the dilution factor used.

The dilution of the concentrated protein solution and the resulting reduction in ionic strength facilitates the formation of a cloud of highly bound protein molecules in the form of discrete protein droplets in the form of micelles. The protein micelles are allowed to settle to form aggregated, agglomerated, dense, amorphous, sticky, gluten-like protein micelles. Sedimentation may be assisted, for example, by centrifugation. Such induced settling reduces the liquid content of the protein microblock, thereby reducing the moisture content from generally about 70% to about 95% by weight of the total microblock to a value of generally about 50% to about 80% by weight. Reducing the moisture content of the micro-agglomerates in this manner also reduces the enclosed salt content of the micro-agglomerates and, therefore, the salt content of the dried isolate.

In a batch operation, a batch of concentrated protein solution is added to a quiescent cold water body having a desired volume, as discussed above. The dilution of the concentrated protein solution and the resulting reduction in ionic strength facilitates the formation of a cloud of highly bound protein molecules in the form of discrete protein droplets in the form of micelles. In a batch procedure, the protein micelles are allowed to settle in cold water to form aggregated, agglomerated, dense, amorphous, sticky gluten-like protein micelles (PMM). Sedimentation may be assisted, for example, by centrifugation. Such induced settling reduces the liquid content of the protein microblock, thereby reducing the moisture content from generally about 70% to about 95% by weight of the total microblock to a value of generally about 50% to about 80% by weight. Reducing the moisture content of the micro-agglomerates in this manner also reduces the enclosed salt content of the micro-agglomerates and, therefore, the salt content of the dried isolate.

Alternatively, the dilution operation may be performed continuously by passing the concentrated protein solution continuously through one inlet of the tee while supplying dilution water to the other inlet of the tee, allowing mixing in the tube. Dilution water is supplied to the tee at a rate sufficient to achieve the desired degree of dilution of the concentrated protein solution.

Mixing of the concentrated protein solution and dilution water in the tube initiates protein micelle formation, and the mixture is continuously fed from the outlet of the T-tube into the settling vessel, allowing the supernatant to overflow therefrom when full. The mixture is preferably supplied to the liquid body in the settling vessel in such a way that turbulence in the liquid body is minimized.

In a continuous procedure, the protein micelles are allowed to settle in the settling vessel to form aggregated, agglomerated, dense, amorphous, sticky, gluten-like Protein Micellar Mass (PMM), and the procedure continues until the desired amount of PMM has accumulated in the bottom of the settling vessel, whereupon the accumulated PMM is removed from the settling vessel. Instead of settling by precipitation, the PMM can be continuously separated by centrifugation.

The use of a combination of process parameters to concentrate the protein solution to a preferred protein content of at least about 200 g/L and a dilution factor of about 10 to about 20 results in higher, typically significantly higher, yields of protein in the form of protein micro-agglomerates recovered from the raw meal extract, as well as a much purer isolate in terms of protein content than achieved using any of the known prior art protein isolate formation procedures discussed in the aforementioned U.S. patents.

By utilizing a continuous process for recovering canola protein isolate, the initial protein extraction step can be significantly reduced in time for the same level of protein extraction and significantly higher temperatures can be employed in the extraction step as compared to a batch process. Furthermore, in continuous operation there are fewer opportunities for contamination than in batch procedures, resulting in higher product quality, and the process can be performed in a more compact plant.

The settled isolate, in the form of an amorphous, aggregated, sticky, gelatinous, gluten-like protein mass, called "protein micellar mass" or PMM, is separated from the residual aqueous phase or supernatant, for example by decanting the residual aqueous phase from the settled mass or via centrifugation. The PMM may be used in wet form or may be dried by any convenient technique, such as spray drying, freeze drying or vacuum drum drying, to a dry form. The dried PMM has a high protein content, at least about 90 wt% protein, preferably at least about 100 wt% (calculated as N x 6.25.25) d.b., and is substantially non-denatured (as determined by differential scanning calorimetry). The dried PMM has a low residual fat content, which may be less than about 1 wt%.

The supernatant from the PMM formation and settling steps contains a significant amount of canola protein that does not precipitate in the dilution step.

The supernatant from the dilution step, after PMM removal, may be concentrated to increase its protein concentration. Such concentration is achieved using any convenient selective membrane technique, such as ultrafiltration, using membranes with appropriate molecular weight cut-offs, allowing low molecular weight species, including salts extracted from the source material, carbohydrates, pigments and other low molecular weight materials, to pass through the membrane while retaining a substantial proportion of the canola protein in solution. Ultrafiltration membranes having a molecular weight cut-off of about 3,000 to about 100,000 daltons, preferably about 5,000 to about 10,000 daltons, can be used, taking into account different membrane materials and configurations. Concentrating the supernatant in this manner also reduces the volume of liquid required to perform drying to recover the protein, and thus reduces the energy required for drying. Prior to drying, the supernatant is typically concentrated to a protein content of about 100-400 g/L, preferably about 200-300 g/L.

The concentrated supernatant may be dried to a dry form by any convenient technique, such as spray drying, freeze drying or vacuum drum drying, to provide further canola protein isolate. Such further canola protein isolates have a high protein content, typically in excess of about 90 wt% protein (calculated as Kjeldahl nx 6.25), and are substantially non-denatured (as determined by differential scanning calorimetry). If desired, the wet PMM may be combined with the concentrated supernatant prior to drying the combined protein stream by any convenient technique to provide a combined canola protein isolate. The combined canola protein isolate has a high protein content, in excess of about 90 wt% (calculated as Kjeldahl nx 6.25), and is substantially non-denatured (as determined by differential scanning calorimetry).

Alternatively, the supernatant from the PMM separation may be processed by an alternative procedure to recover further canola protein isolate therefrom. For example, as described in co-pending U.S. patent application No. 12/213,500, filed on day 6 and 20 of 2008, the disclosure of which is incorporated herein by reference, the first partially concentrated or concentrated supernatant may be subjected to a heat treatment to precipitate 7S protein therefrom prior to recovery of the canola protein isolate from the heat treated solution. Also as described in co-pending U.S. patent application No. 12/213,500, the supernatant may be subjected to isoelectric precipitation to precipitate 7S protein prior to recovery of the canola protein isolate from the resulting solution.

In another alternative described in U.S. provisional patent application No. 61/136,193 filed on 8/18/2008 (U.S. patent application No. ____ filed ____, WO ____), as assigned to the assignee hereof and the disclosure of which is incorporated herein by reference, the supernatant, which may first be partially concentrated or concentrated, is subjected to treatment with a calcium salt, preferably calcium chloride, prior to recovery of the canola protein isolate.

Additionally, the PMM may be processed to provide a soluble canola protein isolate as described in U.S. provisional patent application No. 61/136,208 filed on 19/8/2008 (U.S. patent application No. ____ filed ____, WO ____), which is assigned to the assignee hereof and the disclosure of which is incorporated herein by reference.

In another alternative procedure, only a portion of the concentrated supernatant may be mixed with at least a portion of the PMM and the resulting mixture dried. The remainder of the concentrated supernatant can be dried as any of the remainder of the PMM. In addition, the dried PMM and the dried supernatant can also be dry mixed in any desired relative proportions.

By operating in this manner, a number of canola protein isolates can be recovered in the form of dried PMM, dried supernatant and dried mixtures of PMM and supernatant in various weight ratios, typically from about 5:95 to about 95:5 by weight, which may be desirable to obtain different functional and nutritional properties.

Examples

Example 1：

This example describes the production of a novel canola protein isolate in accordance with one embodiment of the present invention.

The 'a' kg canola seeds were passed through a grinder to completely grind the seeds. 'b' kg of ground seeds was added to 'c' L'd' M NaCl solution at ambient temperature and agitated for 30 minutes to provide an aqueous protein solution. Residual canola seed material is removed and the resulting protein solution is partially clarified by centrifugation to produce a partially clarified 'e' L protein solution having a 'f' wt% protein content. The partially clarified protein solution was defatted with a cream separator and then filtered for further clarification, resulting in a volume of 'g' L of solution having a 'h' wt% protein content.

An aliquot of the protein extract solution of ' i ' L was reduced in volume to ' j ' L by concentration on a Polyethersulfone (PES) membrane with a molecular weight cutoff of ' k ' daltons, and subsequently diafiltered on the same membrane with ' L ' volume ' M NaCl solution. The diafiltered retentate (retentate) was then pasteurized at 60 ℃ for 1 minute. The resulting 'n' kg of pasteurized concentrated protein solution had a protein content of 'o' wt%.

The concentrated solution 'q' was diluted at 'p' ° c into cold Reverse Osmosis (RO) purified water having a temperature 'r' ° c. A white cloud formed immediately and was allowed to settle. The upper dilution water was removed and the precipitated, viscous, sticky mass (PMM) was recovered by centrifugation in the yield of's' wt% filtered protein solution. The dried PMM-derived protein was found to have a protein content of't'% (N x 6.25.25) d.b. The product was given the name ` u ` C300.

The parameters 'a' to 'u' for the 2 runs are set forth in table I below:

TABLE I

The supernatant of 'v' L was heated to 80 ℃ for 10 minutes, and then centrifuged to remove precipitated protein. The centrifuged heat-treated supernatant was then reduced in volume from 'w' L to 'x' L by ultrafiltration using a Polyethersulfone (PES) membrane with a molecular weight cutoff of 'y' daltons, and the concentrate was then diafiltered on the same membrane with a 'z' volume of pH 3 RO water. The diafiltered concentrate contained 'aa' wt.% protein. For additional protein recovered from the supernatant, the overall protein recovery of the filtered protein solution was 'ab' wt%. The concentrate was spray dried to form the final product, which was given the name 'u' C200HS and had a protein content of 'ac'% (N x 6.25.25) d.b.. The parameters 'u' to 'ac' for the 2 runs are set forth in table II below:

TABLE II

Example 2：

This example describes the production of a novel canola protein isolate in accordance with one embodiment of the present invention.

'a' kg of myrosinase-inactivated canola seeds were passed through a grinder to completely grind the seeds. 'b' kg of ground seeds was added to 'c' L'd' M NaCl solution at ambient temperature and agitated for 30 minutes to provide an aqueous protein solution. Residual canola seed material is removed and the resulting protein solution is partially clarified by centrifugation to produce a partially clarified protein solution having an 'e' wt% protein content. The partially clarified protein solution was defatted with a cream separator and then filtered for further clarification, resulting in a volume 'f' L of solution having a 'g' wt% protein content.

The 'h' L aliquot of protein extract solution was reduced to 'i' kg by concentration on a polyvinylidene 1, 1-difluoroethylene (PVDF) membrane with a molecular weight cutoff of 'j' daltons. The retentate was then pasteurized at about 62 ℃ for 10 minutes. The resulting 'k' kg of pasteurized concentrated protein solution had a protein content of 'l' wt%.

The concentrated solution 'n' was diluted at'm' deg.c into cold RO water having a temperature of 'o' deg.c. A white cloud formed immediately and was allowed to settle. The upper dilution water was removed and the precipitated, viscous, sticky mass (PMM) was recovered by centrifugation in a yield of 'p' wt% filtered protein solution. The dried PMM-derived protein was found to have a protein content of 'q'% (N x 6.25.25) d.b. The product was given the name 'r' C300.

The parameters 'a' to 'r' are set forth in table III below:

TABLE III

The supernatant of's' L was heated to about 87 ℃ for 5 minutes, and then centrifuged to remove precipitated protein. The centrifuged heat treated supernatant was then reduced from't' L to 'u' kg by ultrafiltration using a Polyethersulfone (PES) membrane with a molecular weight cutoff of 'v' daltons. The retentate contains 'w' wt% protein. For additional protein recovered from the supernatant, the overall protein recovery of the filtered protein solution was 'x' wt%. The retentate was spray dried to form the final product, having a protein content of 'y'% (N x 6.25.25) d.b. and given its name 'r' C200 HS.

The parameters 'r' to 'y' are set forth in table IV below:

TABLE IV

Example 3：

This example describes the production of canola protein isolate using meal prepared from myrosinase-inactivated canola seed used in example 2.

'a' kg of myrosinase-inactivated canola meal was added to 'b' L 'c' M NaCl solution at ambient temperature and agitated for 30 minutes to provide an aqueous protein solution. Residual canola meal is removed and the resulting protein solution is partially clarified by centrifugation to produce a partially clarified'd' L protein solution having an 'e' wt% protein content. This solution was then filtered for further clarification, resulting in a volume 'f' L of solution having a 'g' wt% protein content.

The 'h' L aliquot of protein extract solution was reduced to 'i' kg by concentration on PVDF (polyvinylidene 1, 1-difluoroethylene) membranes with a molecular weight cutoff of 'j' daltons. The retentate was then pasteurized at about 63 ℃ for 10 minutes. The resulting 'k' kg of pasteurized concentrated protein solution had a protein content of 'l' wt%.

The concentrated solution 'n' was diluted at'm' deg.c into cold RO water having a temperature of 'o' deg.c. A white cloud formed immediately and was allowed to settle. The upper dilution water was removed and the precipitated, viscous, sticky mass (PMM) was recovered by centrifugation in a yield of 'p' wt% filtered protein solution. The dried PMM-derived protein was found to have a protein content of 'q'% (N x 6.25.25) d.b. The product was given the name 'r' C300.

The parameters 'a' to 'r' for the 3 runs are set forth in table V below:

TABLE V

The supernatant of's' L was heated to about 85 ℃ for 8 minutes, and then centrifuged to remove precipitated protein. The centrifuged heat treated supernatant of't' L was then reduced to 'u' kg by ultrafiltration using a Polyethersulfone (PES) membrane with a molecular weight cutoff of 'v' daltons. The retentate contains 'w' wt% protein. For additional protein recovered from the supernatant, the overall protein recovery of the filtered protein solution was 'x' wt%. The retentate was spray dried to form the final product, having a protein content of 'y'% (N x 6.25.25) d.b. and given its name 'r' C200 HS.

The parameters 'r' to 'y' for the 2 runs are set forth in table VI below:

TABLE VI

The color of the dried product produced in the above examples was analyzed using a HunterLab ColorQuest XE instrument operating in reflectance mode. The results are shown in table VII.

Table VII: color results for the dried products from examples 2 and 3:

canola protein isolates prepared from ground seeds were found to be brighter (higher L value) than the equivalent products produced from canola meal prepared from the same seeds. The C200HS produced from the seed was slightly greener than the product produced from the flour, while the C300 product had a very similar a-value, independent of the starting material. The C200HS prepared from the ground seeds was less yellow than the C200HS prepared from flour, but the trend was opposite for the C300 product. Samples with higher values of L are generally considered more acceptable, as the "L" values indicate whiteness. The maximum value of 100 indicates a white sample, and the minimum value of 0 indicates a black sample.

Summary of the disclosure

The present disclosure generally relates to the production of canola protein isolates from canola oil seeds in which there is no initial removal of oil from the seeds. Modifications are possible within the scope of the invention.

Claims (12)

1. A process for preparing a canola protein isolate, which comprises:

the canola oil seed is ground,

extracting the ground canola oil seeds with an aqueous extraction medium to solubilize canola protein and fat in the ground canola oil seeds to form an aqueous canola protein solution,

separating the aqueous canola protein solution from residual ground canola oil seeds,

defatting the aqueous canola protein solution,

clarifying the defatted aqueous canola protein solution,

concentrating the clarified aqueous canola protein solution while maintaining the ionic strength substantially constant to form a concentrated canola protein solution,

diluting said concentrated protein solution into chilled water to facilitate formation of canola protein micelles,

collecting said canola protein micelles as protein micelles, and

drying the protein mini-agglomerate to form a canola protein isolate having a protein content of at least about 90 wt% (N x 6.25.25) d.b.protein.

2. The process of claim 1 wherein the aqueous extraction medium is a brine solution having an ionic strength of at least about 0.05M having a pH of about 5 to about 6.8 to form a canola protein solution having a concentration of about 3 to about 40 g/L.

3. The process of claim 2, wherein an antioxidant is present in the aqueous extraction medium.

4. The method of claim 1, wherein the degreasing step is achieved by: cooling the canola protein solution to a temperature of about 3 ℃ to about 7 ℃ and removing fat separated from the canola protein solution.

5. The process of claim 4 wherein after said defatting step, a color removal step is performed on said isolated aqueous canola protein solution.

6. The process of claim 1 wherein the aqueous canola protein solution is concentrated to a protein concentration of about 50 to about 250 g/L.

7. The process of claim 6 wherein the concentrated canola protein solution is subjected to a diafiltration step to provide a concentrated and diafiltered canola protein solution.

8. The method of claim 7, wherein an antioxidant is present during at least a portion of the diafiltration operation.

9. The process of claim 7 wherein the concentrated and diafiltered canola protein solution is subjected to a color removal operation.

10. The process of claim 7 wherein the concentrated and diafiltered canola protein solution is subjected to a pasteurization step.

11. The method of claim 1 wherein said diluting step is accomplished by diluting said concentrated protein solution from about 5-fold to about 25-fold at a temperature of less than about 15 ℃.

12. The process of claim 1 wherein the supernatant from the collection of protein micro-agglomerates is processed to form a further canola protein isolate having a protein content of at least about 90 wt% (N x 6.25.25) d.b..