FOAM COMPRISING SOLUBLE RAPESEED PROTEIN ISOLATE

Abstract

A foam comprising water and native rapeseed protein isolate comprising 40 to 65 wt. % cruciferins and 35 to 60 wt. % napins and having a solubility of at least 90% over a pH range from 3 to 10 at a temperature of 232 C.

Claims

1. A foam comprising: i) 80 to 95 wt. % of water, and ii) 5 to 20 wt. % native rapeseed protein isolate comprising 40 to 65 wt. % cruciferins and 35 to 60 wt. % napins and having a solubility of at least 88% over a pH range from 3 to 10 at a temperature of 232 C., iii) a protein selected from the group consisting of whey protein, soy protein, whole soybean protein, milk protein, safflower protein, egg protein, rapeseed protein not including cruciferins or napins, isolates of any thereof, concentrates of any thereof and combinations of any thereof, wherein i)+ii)+iii) add up to 100 wt. % or less.

2. A foam according to claim 1 wherein the native rapeseed protein isolate has a protein content of at least 90 wt. % on a dry weight basis and a solubility of at least 90% over a pH range from 3 to 10 at a temperature of 232 C.

3. A foam according to claim 1 wherein the native rapeseed protein isolate in an aqueous 2 wt. % solution has a conductivity of less than 9000 S/cm over a pH range of 2 to 12 measured using a Hach sensION+EC71 conductivity meter.

4. A foam according to claim 1 wherein the native rapeseed protein isolate has a phytate level less than 0.4 wt. %.

5. A foam according to claim 1 wherein said protein mentioned under iii) is egg protein.

6. A foam according claim 1 where total protein used in (ii)+(iii) comprises at least 25% of rapeseed protein isolate (ii).

7. A foam according to claim 5 comprising rapeseed protein isolate and egg white protein in a ratio in the range of from 25:75 to 75:25.

8. A process for obtaining a foam comprising: i) 80 to 95 wt. % of water, and ii) 5 to 20 wt. % native rapeseed protein isolate comprising 40 to 65 wt. % cruciferins and 35 to 60 wt. % napins and having a solubility of at least 88% over a pH range from 3 to 10 at a temperature of 232 C., iii) a protein selected from the group consisting of whey protein, soy protein, whole soybean protein, milk protein, safflower protein, egg protein, rapeseed protein not including cruciferins or napins, isolates of any thereof, concentrates of any thereof and combinations of any thereof, wherein i)+ii)+iii) add up to 100 wt. % or less comprising: a) mixing the rapeseed protein isolate with water to form a paste; b) adding water to the paste obtained in a); c) adding before, after or during b) a protein selected from the group consisting of whey protein, soy protein, whole soybean protein, milk protein, safflower protein, egg protein, rapeseed protein not including cruciferins or napins, isolates of any thereof, concentrates of any thereof and combinations of any thereof, d) whipping the mixture obtained in c) into a foam.

9. A process according to claim 8 wherein after c) the pH is adjusted to neutral.

10. A product comprising a foam according to claim 1 in a food product.

11. Food product comprising a foam according to claim 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0024] In a first aspect according to the present invention there is provided a foam comprising: [0025] i) 80 to 95 wt. % of water, and [0026] ii) 5 to 20 wt. % native rapeseed protein isolate comprising 40 to 65 wt. % cruciferins and 35 to 60 wt. % napins and having a solubility of at least 88% over a pH range from 3 to 10 at a temperature of 232 C., [0027] iii) a protein selected from the group consisting of whey protein, soy protein, whole soybean protein, milk protein, safflower protein, egg protein, rapeseed protein not including cruciferins or napins, isolates of any thereof, concentrates of any thereof and combinations of any thereof,

[0028] wherein i)+ii)+iii) add up to 100 wt. % or less.

[0029] In one embodiment it was found that optimal results in terms of solubility and foaming capacity were obtained when the wt. % of cruciferins and napins are approximately equal. Hence, preferably 42 to 60 wt. % cruciferins and 40 to 58 wt. % napins, more preferably 45 to 60 wt. % cruciferins and 40 to 55 wt. % napins, most preferably 47 to 55 wt. % cruciferins and 45 to 53 wt. % napins. With the proviso that the combined wt. % of both cruciferin and napin do not exceed 100%.

[0030] Preferably the native rapeseed protein isolate has a solubility of at least 88%, more preferably at least 90%, more preferably at least 92%, still more preferably of at least 94% and still more preferably of at least 96% when measured over a pH range from 3 to 10 at a temperature of 232 C. This is also known as the soluble solids index (SSI), as described by Morr et al. (J. Food Sci. (1985) 50, 1715-1718) and modified as per the Test Method section of the instant invention.

[0031] For use in human food consumption the native rapeseed protein isolate preferably comprises a low level of salt. This is measured by the conductivity. Preferably the conductivity of the native rapeseed protein isolate in a 2 wt. % aqueous solution is less than 9000 S/cm over a pH range of 2 to 12. More preferably the conductivity of the native rapeseed protein isolate in a 2 wt. % aqueous solution is less than 4000 S/cm over a pH range of 2.5 to 11.5. For comparison, the conductivity of a 5 g/l aqueous sodium chloride solution is around 9400 S/cm.

[0032] Preferably the native rapeseed protein isolate has a phytate level of less than 0.4 wt. %, more preferably less than 0.25 wt. % and most preferably less than 0.15 wt. %. Addition of phytate to rapeseed protein isolates was observed to have negative effects on solubility and foaming properties as reported by Kroll (Die Nahrung (1991) 35, 619-624).

[0033] Preferably the native rapeseed protein isolate has a protein content of at least 90 wt. % (calculated as Kjeldahl N6.25) on a dry weight basis, more preferably at least 94 wt. %, most preferably at least 96 wt. % and especially at least 98 wt. %.

[0034] The water (i) should be water suitable for human consumption. Preferably the foam comprises 15 to 50 wt. % of water and more preferably 15 to 30 wt. % of water.

[0035] The foam comprises, in addition to the rapeseed protein isolate (ii) a protein (iii) selected from the group consisting of whey protein, soy protein, whole soybean protein, milk protein, safflower protein, rapeseed protein not including (ii), an egg protein, isolates of any thereof, concentrates of any thereof, and combinations of any thereof.

[0036] Preferably the total protein used (ii)+(iii) comprises at least 25%, more preferably at least 40% and most preferably at least 60% of rapeseed protein isolate.

[0037] Surprisingly it was found that a combination of approximately equal amounts of egg white protein and rapeseed protein resulted in a more stable foam than the use of either alone, indicating a synergistic effect. Therefore, in a most preferred embodiment there is provided a foam according to the invention comprising rapeseed protein isolate and egg white protein in a ratio in the range of from 25:75 to 75:25, more preferably of from 35:65 to 65:35, most preferably of from 45:55 to 55:45. The resultant combination has a foaming stability higher by 20% than the average of the foaming stability using only rapeseed protein isolate or only egg white protein.

[0038] The foam of the present disclosure may further comprise other ingredients, such as, for example, food starches, sweeteners, spices, seasonings (including salt), food pieces, stabilizers, antioxidants, sterols, soluble fiber, gums, flavorings, preservatives, colorants, and various combinations of any thereof. The foam may be prepared using processes well known in the art.

[0039] The rapeseed protein isolate is produced from rapeseed press meal (also referred to as cake), the by-product of rapeseed oil production. Preferably the native rapeseed protein isolate is substantially un-hydrolyzed. By substantially un-hydrolyzed is meant that the protein is not deliberately hydrolyzed. Preferably the rapeseed protein isolate is obtained in a process where the levels of napin and cruciferin are kept substantially constant (i.e. neither the napin or cruciferin levels are deliberately increased). Preferably the rapeseed protein isolate is obtained in a process without a fractionating step.

[0040] The process starts with an extraction step, in which rapeseed meal (preferably cold-pressed rapeseed oil seed meal) is mixed with an aqueous salt solution, for example 0 to 5% sodium chloride, at a temperature between 4 to 75 C., more preferably 20 to 75 C. and most preferably 40 to 75 C. Preferably the meal to water ratio is in the range of from 1:5 to 1:20. After a period in the range of from 5 min to 2 hours, preferably 30 minutes to 1 hour, the protein rich solution (extract) is separated from the insoluble material. The protein rich solution is hereafter referred to as the extract. The pH of the extract is adjusted and the extract is further processed to clarify the material and remove non-protein substances. The residual fat and formed precipitates are removed via a solid/liquid separation step (e.g. a membrane filter press or centrifugation). The extract is then concentrated and washed in an ultrafiltration/diafiltration (UF/DF) step. The UF/DF step has the purpose of concentrating the protein and removing anti-nutritional factors (e.g. polyphenols, residual phytate, glucosinolates). Finally, the washed concentrate may be dried in a suitable dryer, such as a spray drier (single or multistage) with an inlet temperature in the range of from 150 to 200 C. and an outlet temperature in the range of from 50 to 100 C. resulting in the rapeseed protein isolate.

[0041] In a second aspect of the present invention there is provided a process for obtaining a foam comprising: [0042] i) 80 to 95 wt. % of water, and [0043] ii) 5 to 20 wt. % native rapeseed protein isolate comprising 40 to 65 wt. % cruciferins and 35 to 60 wt. % napins and having a solubility of at least 88% over a pH range from 3 to 10 at a temperature of 232 C., [0044] iii) a protein selected from the group consisting of whey protein, soy protein, whole soybean protein, milk protein, safflower protein, egg protein, rapeseed protein not including cruciferins or napins, isolates of any thereof, concentrates of any thereof and combinations of any thereof,

[0045] wherein i)+ii)+iii) add up to 100 wt. % or less, comprising: [0046] a) mixing the rapeseed protein isolate with water to form a paste: [0047] b) adding water to the paste obtained in step a); [0048] c) adding before, after or during step b) a protein selected from the group consisting of whey protein, soy protein, whole soybean protein, milk protein, safflower protein, egg protein, rapeseed protein not including cruciferins or napins, isolates of any thereof, concentrates of any thereof and combinations of any thereof, [0049] d) whipping the mixture obtained in step c) into a foam.

[0050] In another embodiment the pH of the mixture mentioned under c) above is adjusted to neutral, i.e. to pH 7.01.0, preferably to pH 7.00.5, most preferably to pH 7.00.3 by the addition of acid or base, as the case may be.

[0051] In a third aspect according to the invention there is also provided the use of a foam according to the invention in food products and food product comprising a foam according the invention. Hence, the foaming properties of egg white and milk protein to provide a suitable aerated structure, used in such products as nougats, macaroons and meringues, may be reproduced by utilization of the rapeseed protein isolate.

[0052] In a fourth aspect of the invention there is provided a food product comprising a foam according to the first aspect of the invention, i.e. a foam comprising: [0053] i) 80 to 95 wt. % of water, and [0054] ii) 5 to 20 wt. % native rapeseed protein isolate comprising 40 to 65 wt. % cruciferins and 35 to 60 wt. % napins and having a solubility of at least 90% over a pH range from 3 to 10 at a temperature of 232 C., [0055] iii) a protein selected from the group consisting of whey protein, soy protein, whole soybean protein, milk protein, safflower protein, egg protein, rapeseed protein not including cruciferins or napins, isolates of any thereof, concentrates of any thereof and combinations of any thereof,
Non-limiting Examples and comparative examples of the invention are described below.

EXAMPLES

Test Methods

Protein Content

[0056] Protein content was determined by the Kjeldahl method according to AOAC Official Method 991.20 Nitrogen (Total) in Milk, using a conversion factor of 6.25 was used to determine the amount of protein (% (w/w)).

Conductivity

[0057] The conductivity of native rapeseed protein isolate in a 2 wt. % aqueous solution was measured using a conductivity meter: Hach sensION+EC71.

Solubility Test

[0058] The below solubility test is adapted from Morr et al. (J. Food Sci. (1985) 50, 1715-1718), the difference being the use of water instead of 0.1M sodium chloride.

[0059] Sufficient protein powder to supply 0.8 g of protein was weighed into a beaker. A small amount of demineralized water was added to the powder and the mixture was stirred until a smooth paste was formed. Additional demineralized water was then added to make a total weight of 40 g (yielding a 2% w/w protein dispersion). The dispersion was slowly stirred for at least 30 min using a magnetic stirrer. Afterwards the pH was determined and adjusted to the desired level (2, 3, etc.) with sodium hydroxide or hydrochloric acid. The pH of the dispersion was measured and corrected periodically during 60 minutes stirring. After 60 minutes of stirring, an aliquot of the protein dispersion was reserved for protein content determination (Kjeldahl analysis). Another portion of the sample was centrifuged at 20,000 G for 2 minutes. The supernatant and pellet were separated after centrifugation. The protein content of the supernatant was also determined by Kjeldahl analysis.

Protein solubility (%)=(protein in supernatant/protein in total dispersion)100.

[0060] Alternative methods for determining solubility are available and in some case use buffers, like borate-phosphate buffer in WO 2011/057408. However, such as values are incomparable with the ones obtained in the instant application that are determined in the absence of buffer.

Comparative Example 1

Egg White Foam

[0061] In this example a typical egg white foam was prepared. Foam capacity and stability were measured. All ingredients were at ambient temperature (232 C.) and quantities are shown in Table 1 below. Sufficient egg white protein (EWP, available from Sanovo) to supply 11.69 g of protein was weighed into a 250 cm.sup.3 beaker. A small amount of tap water was added to the powder and the mixture was stirred until a smooth paste formed. Additional tap water was then added to make a total weight of 125 g (yielding a 9.35% protein mixture). The mixture was slowly stirred for at least 30 min using a magnetic stirrer. Afterwards the pH was determined, and adjusted to neutral (pH 7) with sodium hydroxide or hydrochloric acid. The pH of the mixture was corrected periodically to pH 7 during 60 minutes of stirring. Protein mixture (100 cm.sup.3) was measured (both the volume and weight were noted) and transferred into a mixer bowl of the Hobart mixer and was whipped at 450 rpm for 150 seconds. After whipping, the foam surface was smoothed in the mixer bowl. The height of the foam was measured three times by a dipstick pin. The foam volume was calculated by means of a conversion of the foam height (mm) to volume (cm.sup.3). All the foam was transferred from the mixer bowl into a funnel (with perforated insert bottom plate), which was fixed in a tripod. A 50 cm.sup.3 graduated glass cylinder was placed below the funnel, and the amount of liquid draining from the foam was monitored for 60 minutes (the 60 minutes countdown was started as soon as the whipping was stopped). [0062] Foam capacity (%)=(V.sub.f/VI.sub.o)100%, in which V.sub.f=foam volume (cm.sup.3) and VI.sub.o=liquid volume at time t=0 (100 cm.sup.3). [0063] Foam stability (%)=((VI.sub.oVI.sub.t)/VI.sub.o)100%, in which VI.sub.o=start liquid volume at time t=0 (100 cm.sup.3); Vlt=drain liquid volume after t=60 min (cm.sup.3).

[0064] The resultant foam had a capacity of 1463% and stability of 70 to 75%.

TABLE-US-00001 TABLE 1 Protein concentration Ingredient Dosage in final mixture EWP (85% protein content) 13.75 g 9.35% Water 111.25 g

Comparative Example 2

Classic Rapeseed Protein Isolate (RPI) Foam

[0065] Comparative example 1 was repeated but with a classic rapeseed protein isolate (RPI) available from DSM with a solubility less than 90% across a pH range of 3 to 8 and less than 70% across a pH range of 4 to 6 (i.e. not according to the invention) instead of egg white protein using the quantities described in Table 2 below. The resultant foam had a capacity of 2278% and stability of 55%.

TABLE-US-00002 TABLE 2 Ingredient Dosage Protein concentration in final mixture Classic RPI 13.0 g 9.35% Water 112 g

Comparative Example 3

Classic RPI Plus Egg White Foam

[0066] Comparative example 1 was repeated but with 50% classic RPI (i.e. not according to the invention) and 50% EWP using the quantities described in Table 3 below. The resultant foam had a capacity of 974%, and stability of 40%. The mixture of classic RPI and EWP gave a reduced foam capacity as well as reduced foam stability.

TABLE-US-00003 TABLE 3 Protein concentration Ingredient Dosage in final mixture Classic RPI 6.5 g 4.67% EWP (85% protein content) 6.9 g 4.67% Water 111.6 g

Example 1

Preparation of Rapeseed Protein Isolate (RPI90)

[0067] The rapeseed protein isolate was produced from cold-pressed rapeseed oil seed meal having an oil content of less than 15% on dry matter basis, cleaned and processed below 75 C.

[0068] In the extraction step, the cold-pressed rapeseed oil seed meal was mixed with an aqueous salt solution (1 to 5% sodium chloride), at a temperature between 40 to 75 C. The meal to aqueous salt solution ratio was in the range of from 1:5 to 1:20. After about 30 minutes to 1 hour the protein rich solution (extract) was separated from the insoluble material. The pH of the extract was adjusted to neutral and the extract was further processed to clarify the material and remove non-protein substances.

[0069] In the decreaming step, the residual fat was removed via a liquid/liquid separation step using centrifugation. Non-protein substances were removed by adjusting the pH of the material to neutral in the presence of a salt with which phytate precipitates (e.g. calcium chloride). The formed precipitate is removed via a solid/liquid separation step (e.g. a membrane filter press or centrifugation) in which the impurities are removed in a solid salt form (e.g. calcium phytate). The extract was then concentrated and washed in an ultrafiltration/diafiltration (UF/DF) step. Finally, the washed concentrate was dried in a spray drier with an inlet temperature in the range of from 150 to 200 C. and an outlet temperature in the range of from 50 to 100 C. resulting in the rapeseed protein isolate. Several batches were prepared and tested.

[0070] The conductivity of the resultant native rapeseed protein isolates in a 2% solution was less than 4000 S/cm over a pH range of 2.5 to 11.5.

[0071] The resultant native rapeseed protein isolate comprised in the range of from 40 to 65% cruciferins and 35 to 60% napins.

[0072] The resultant native rapeseed protein isolate contained less than 0.26 wt. % phytate.

[0073] The resultant native rapeseed protein isolates had a solubility of at least 88% when measured over a pH range from 3 to 10 at a temperature of 232 C. as shown for two batches in Table 4.

TABLE-US-00004 TABLE 4 pH 3 4 5 6 7 8 9 10 Sample 1 98 96 89 95 95 97 97 98 Solubility (%) Sample 2 102.5 97.5 94.3 93.9 97.0 93.0 94.0 99.8 Solubility (%)

Example 2

Soluble RPI90 Foam

[0074] Comparative example 1 was repeated but with a native RPI according to the invention (RPI90 available from DSM) comprising 40 to 65 wt. % cruciferins and 35 to 60 wt. % napins and having a solubility of at least 90% over a pH range from 3 to 10 at a temperature of 232 C., and a conductivity in a 2 wt. % aqueous solution of less than 9000 S/cm over a pH range of 2 to 12; instead of egg white protein, using the quantities described in Table 5 below. The resultant foam had a capacity of 2930% and stability of 70%.

TABLE-US-00005 TABLE 5 Ingredient Dosage Protein concentration in final mixture RPI90 13 g 9.35% Water 112 g

Example 3

Soluble RPI90 Plus Egg White Foam

[0075] Comparative example 1 was repeated but with 50% RP190 and 50% EWP using the quantities described in Table 6 below. The resultant foam had a capacity of 2376%, and stability of 89%. The mixture of RP190 and EWP didn't destroy foaming capacity. The foaming stability (89%) was higher than that stabilized by RP190 (70%) or EWP (70 to 75%) alone, therefore demonstrating a synergistic effect.

TABLE-US-00006 TABLE 6 Protein concentration Ingredient Dosage in final mixture RPI90 6.5 g 4.67% EWP (85% protein content) 6.9 g 4.67% Water 111.6 g