PRODUCTION OF NON-PRECIPITATED PLANT PROTEIN ISOLATES

Abstract

Disclosed is a method for preparing a protein isolate displaying a purity higher than 80% from plant parts, the method including the following successive steps: a) washing the plant parts in acidic conditions, thereby obtaining acid washed plant parts; b) contacting the acid washed plant parts with an alkaline solution; and c) recovering the liquid fraction thereby obtaining a protein isolate displaying a purity higher than 80%. The method does not include any acidic precipitation step.

Claims

1. A legume protein isolate from plant parts, wherein said protein isolate comprises at least 80% of proteins on dry matter and comprises less than 0,10% of alpha-galactosides by weight of the protein isolate.

2. The legume protein isolate according to claim 1, wherein said protein isolate has at least one feature selected from the group consisting of: a less yellow color, by comparison to a protein isolate obtained by a method comprising a first step of alkaline extraction followed by a second step of acid precipitation, an improved taste by comparison to a protein isolate obtained by a method comprising a first step of alkaline extraction followed by a second step of acid precipitation, a neutral odor without beany smell, a solubility higher than 50% at pH8 in a 2% protein solution, an improved foaming capacity, by comparison to a protein isolate obtained by a method comprising a first step of alkaline extraction followed by a second step of acid precipitation, a gelling property and a low viscosity.

3. A composition comprising at least one legume protein isolate according to claim 1.

4. The composition according to claim 3, wherein said composition is a food composition, a feed composition, a pet-food composition, a cosmetic composition, a nutraceutical composition or a pharmaceutical composition.

5. A method for preparing a legume protein isolate from plant parts according to claim 1, said method comprising the following successive steps: a) washing said plant parts in acidic conditions, thereby obtaining acid washed plant parts; b) contacting said acid washed plant parts with an alkaline solution, and c) recovering the liquid fraction, thereby obtaining a protein isolate displaying a purity higher than 80%, wherein said method does not comprise any acidic precipitation step.

6. The method according to claim 5, wherein the pH of said washing step is of 3.5 to 5.

7. The method according to claim 5, wherein said acid washed plant parts are recovered at the end of said washing step by solid/liquid separation.

8. The method according to claim 5, wherein said acid washed plant parts have a pH comprised between 3.5 and 5.

9. The method according to claim 5, said method further comprising between the washing step a) and the contacting step b), a step of rinsing said acid washed plant parts with an aqueous solution.

10. The method according to claim 9, wherein said acid washed plant parts have a pH comprised between 3.5 and 5 after said rinsing step.

11. The method according to claim 5, wherein said alkaline solution used in step b) has a pH of 7 to 9.

12. The method according to claim 5, wherein said liquid fraction is recovered at step c) by solid/liquid separation.

13. The method according to claim 5, wherein said steps b) and c) are repeated at a higher pH.

14. The method according to claim 5, wherein said protein isolate is directly obtained at said recovering step c).

15. The method according to claim 5, further comprising after said recovering step c), a neutralization step, a heat treatment step, a concentration step and/or a drying step.

16. The method according to claim 5, wherein said plant parts are seeds.

17. The method according to claim 16, wherein said seeds are provided in the form of flour in said washing step a).

18. A method of improving digestive comfort, wherein said method comprises using a protein isolate according to claim 1 as a nutritional ingredient.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0219] FIG. 1: Pilot scale process description

[0220] FIG. 2: Evaluation of the foaming capacity

[0221] FIG. 3: Proteins solubility

[0222] FIG. 4: Gelling property of standard pH-metric proteins

[0223] FIG. 5: Gelling property of proteins obtained by the method of the invention

[0224] FIG. 6: Viscosity of proteins solution (10% DS)

[0225] FIG. 7: Viscosity evolution according to the DS content

EXAMPLES

Example 1: Process Development on Faba Bean

[0226] The aim of these pre-series of tests was to define the main steps of the proteins' extraction and purification process. There were performed with dehulled faba bean flour, at lab scale.

[0227] Materials and methods are described in Table 2.

TABLE-US-00002 TABLE 2 Materials and methods Step Principle Material and method Acid wash 1 Flour and acidified water Flour: Pin milled, dehulled faba bean mixing followed by a solid/ Acidified ultra-pure water with citric acid. liquid separation Citric acid powder quantity = 3% of flour quantity Flour on acidified water ratio: ⅙ Q citric acid + Q water + Q flour = Q.sub.AW1 Temperature: 50° C. pH target, after flour addition: 4.5 Time before solid/liquid separation: 10 min Agitation: magnetic stirrer Acid wash 2 Pellets of acid wash 1 Acidified RO water with citric acid. and acidified water Citric acid/water ratio: Equivalent to acid mixing, followed by a wash 1 solid/liquid separation Acidified water addition: qs Q.sub.AW1 Temperature: 50° C. pH, after pellets addition: 3.6 Time before solid/liquid separation: 10 min Agitation: magnetic stirrer Rinse step Pellets of acid wash and Ultra-pure water addition: qs Q.sub.AW1 water mixing, followed by Temperature: 50° C. a solid/liquid separation pH, after pellets addition: 3.5 Time before solid/liquid separation: 10 min Agitation: magnetic stirrer Extraction Pellets of the rinse step Ultra-pure water: qs Q.sub.AW1 and water mixing at Temperature: 50° C. alkaline pH, followed by a pH adjustment, after pellets addition: 9 solid/liquid separation Time before solid/liquid separation: 10 min Agitation: magnetic stirrer Pellets Pellets of extraction and Ultra-pure water: qs Q.sub.AW1 rewash water mixing, followed by Temperature: 50° C. a solid/liquid separation pH, after pellets addition: 9 Time before solid/liquid separation: 10 min Agitation: magnetic stirrer Solid liquid separation Lab centrifuge: Jouan KR 41 4000 g during 10 min Proteins analyses Nitrogen analysis by Kjeldhal (Foss ®) following the ISO method 5983-2. The proteins (Pt) content is the nitrogen content multiplied by 6.25. Dry solid and ash analyses Prepash system (Precisa ®)

Results and Discussion

[0228] As shown in Table 3, the combination of an acid wash followed by an alkaline extraction allowed the production of a proteins concentrate. The purity of the extract is higher than 80% of proteins on dry basis, without precipitation.

[0229] A second test was performed to decrease the proteins losses during the washing step and to increase the final extract purity.

[0230] Analytical results and mass balance are presented in Table 3. The final purity of the extract was over 85 %, without precipitation. Furthermore, the proteins extraction yield was comparable to a standard pH-metric process:

[0231] 17% of the feed proteins were recovered in the wash and rinse supernatants. This fraction corresponds to the albumin fraction, which is recovered in the precipitate supernatant in a standard pH-metric process.

[0232] 11% of the feed proteins stayed insoluble after extraction. It corresponds to the prolamine and glutelin fractions, which are also not recovered with a standard pH-metric process.

[0233] 65% of the proteins were extracted under alkaline conditions. This yield is comparable to the pH metric process.

Conclusion

[0234] The process of the invention allows the production of a non-precipitated proteins isolate. The extraction yield is not affected compared to prior art pH-metric processes.

TABLE-US-00003 TABLE 3 Mass balance and analytical results Globulins Insoluble Protein purity recovery yield Albumins proteins of alkaline (alkaline recovery yield recovery Example extract extract) (acid extract) yield 1 81% 46% 36% 12% 2 85% 65% 17% 11%

Example 2: Process Improvement on Faba Bean

[0235] The aim of these series of tests was to optimize the process by decreasing the amount of inputs (acid). There were performed with dehulled faba bean flour, at lab scale. Materials and methods are described in Table 4.

TABLE-US-00004 TABLE 4 Materials and methods Step Principle Material and method Acid wash Flour and acidified Flour: Roll milled D90 = 300 μm and Option 1: water mixing followed D50 = 100 μm, dehulled faba bean weak acid by a solid/liquid Acidified ultra-pure water with citric acid + and base separation sodium citrate combination Citric acid powder quantity = 3% of flour quantity Flour on acidified water ratio: ⅙ Q citric acid + Q water + Q flour = Q.sub.AW1 Temperature: 50° C. pH target, after flour addition: 4.5 Time before solid/liquid separation: 10 min Agitation: magnetic stirrer Acid wash Flour and acidified Flour: Roll milled, dehulled faba bean Option 2: water mixing followed Acidified RO water with sulfuric acid strong acid by a solid/liquid Sulfuric acid DS quantity = 1% of flour quantity separation Flour on acidified water ratio: ⅙ Q citric acid + Q water + Q flour = Q.sub.AW1 Temperature: 50° C. pH target, after flour addition: 4.5 Time before solid/liquid separation: 10 min Agitation: magnetic stirrer Rinse step 1 Pellets of acid wash and Ultra-pure water: qs Q.sub.AW1 water mixing, followed Temperature: 50° C. by a solid/liquid pH, after pellets addition: 3.5 separation Time before solid/liquid separation: 10 min Agitation: magnetic stirrer Rinse step 2 Pellets of acid wash and Ultra-pure water: qs Q.sub.AW1 water mixing, followed Temperature: 50° C. by a solid/liquid pH, after pellets addition: 3.5 separation Time before solid/liquid separation: 10 min Agitation: magnetic stirrer Extraction Pellets of the rinse step Ultra-pure water: qs Q.sub.AW1 and water mixing at Temperature: 50° C. alkaline pH, followed by pH adjustment, after pellets addition: 7 a solid/liquid Time before solid/liquid separation: 10 min separation Agitation: magnetic stirrer Pellets Pellets of the rinse step Ultra-pure water: qs Q.sub.AW1 rewash and water mixing at Temperature: 50° C. alkaline pH, followed by pH adjustment, after pellets addition: 9 a solid/liquid Time before solid/liquid separation: 10 min separation Agitation: magnetic stirrer Solid liquid separation Lab centrifuge: Jouan KR 41 4000 g during 10 min Proteins analyses Nitrogen analysis by Kjeldhal (Foss ®) following the ISO method 5983-2. The proteins (Pt) content is the nitrogen content multiplied by 6.25. Dry solid and ash analyses Prepash system (Precisa ®)

Results and Discussion

[0236] As shown in Table 5, there was no significant difference in proteins extraction yield and purity, whatever the citric acid and sodium citrate ratio. Furthermore, the buffer effect was not improved by the sodium citrate addition.

TABLE-US-00005 TABLE 5 pH, weak acid and base effect on the extract proteins purity and yield Test A B C Citric acid/flour content 3.0%  3.6%  5.5%  Citrate Na/flour content 0.0%  2.0%  6.0%  Wash pH 4.45 4.57 4.57 Rinse 1 pH 4.52 4.75 4.73 Rinse 2 pH 4.6  4.86 4.83 Albumin fraction yield 16% 16% 18% Glutelin fraction yield 16% 18% 16% Globulin fraction yield 68% 65% 66% Proteins purity, pH 7 97% 98% 97% Estimated proteins purity, pH 9 91% 93% 92%

[0237] According to these results, the right purity and extraction yield could be achieved as long as the pH was maintained between 4.45 and 4.86.

[0238] The quantity of acid related to the feed flour was however quite high.

[0239] A second set of tests was performed with strong acid to decrease the inputs consumption.

[0240] As presented in Table 6, the extract purity was not affected by the use of sulfuric acid. On another hand the inputs consumption was significantly reduced.

[0241] The buffer effect was not affected by the use of strong acid. The pH could be maintained between 4.6 and 4.7 during the rinse steps.

TABLE-US-00006 TABLE 6 Process validation with a strong acid Test D E Sulfuric acid/flour content 1.1%  1.0%  Wash pH 4.58 4.55 Rinse 1 pH 4.63 4.6  Rinse 2 pH 4.67 4.59 Albumin fraction yield 20% 16% Glutelin fraction yield 17% 18% Globulin fraction yield 63% 63% Proteins purity, pH 7 99% 96% Estimated proteins purity, pH 9 94% 94%

Conclusion

[0242] The process comprising an acidic pre-wash followed by an alkaline extraction could be applied using strong acid, such as sulfuric acid, without affecting the protein extract purity.

[0243] The buffer effect of the acidified pellets was high enough to maintain a low pH during the rinse steps. The use of strong acid allowed a significant reduction of the inputs' consumption.

Example 3: Sequential Extraction

[0244] The method of the invention could be used as a basis of a proteins range development. The acidic washing can be followed by a sequential extraction at different pH to perform proteins cracking.

[0245] Materials and methods for the prewashing and the solid/liquid separation is presented Table 4.

[0246] Extraction steps and the fat analysis were performed as described in Table 7.

TABLE-US-00007 TABLE 7 Materials and methods Step Principle Material and method Extraction 1 Pellets of the rinse step Ultra-pure water: qs Q.sub.AW1 and water mixing at neutral Temperature: 50° C. pH, followed by a solid/ pH adjustment, after pellets addition: 7 liquid separation Time before solid/liquid separation: 10 min Agitation: magnetic stirrer Extraction 2 Pellets of the rinse step Ultra-pure water: qs Q.sub.AW1 and water mixing at Temperature: 50° C. alkaline pH, followed by a pH adjustment, after pellets addition: 8 solid/liquid separation Time before solid/liquid separation: 10 min Agitation: magnetic stirrer Extraction 3 Pellets of the rinse step Ultra-pure water: qs Q.sub.AW1 and water mixing at Temperature: 50° C. alkaline pH, followed by a pH adjustment, after pellets addition: 9 solid/liquid separation Time before solid/liquid separation: 10 min Agitation: magnetic stirrer Fat content NF ISO 11085, B process. Fat content measurement after an acidic hydrolysis.

Results

[0247] As shown in Table 8, extractions at pH 7 and pH 9 allowed the production of proteins isolate. At pH 8 the proteins purity was lower than 85 %. More than 68 % of the globulin fraction was extracted at pH 7.

TABLE-US-00008 TABLE 8 Mass balance, sequential extraction Globulins Insoluble Protein purity recovery yield Albumins proteins Extraction of alkaline (alkaline recovery yield recovery pH extract extract) (acid extract) yield 7 96% 66% 16% 19% 8 82% 9 100% 

[0248] A second test was performed wherein the extraction at pH 7 was directly followed by an extraction at pH 9.

[0249] Results are summarized in Table 9. Again, the main fraction of globulins was extracted at pH 7. The proteins purity was also higher at this pH. Furthermore, the fat content was significantly higher after an extraction at pH 9.

TABLE-US-00009 TABLE 9 Proteins purity and fat content of proteins fraction, according to the extraction pH Extraction condition pH 7 pH 9 Proteins purity 98% 80% Total proteins yield 50% 15% Globulin yield 77% 23% Fat content 1.2%  11.2%.sup. 

[0250] Conclusion:

[0251] The process comprising an acidic pre-washing followed by an alkaline extraction allowed a sequential extraction at different alkaline pH.

[0252] The proteins fraction composition varied according to the extraction pH.

[0253] Furthermore, it seemed that fat could be segregated in one specific proteins fraction. One can also expect different functionalities as the proteins fractions are not soluble at same pH. For example, the fraction, extracted at pH 7 can be used as soluble or instant proteins in beverage applications.

Example 4: Application to Pea Proteins

[0254] The method of the invention was applied on yellow pea seeds. Material and method are described in Table 5. The seeds are thus proved in the form of a flour D90=300 μm and D50=100 μm.

[0255] The alkaline extract purity was higher than 85 % of proteins on dry matter and the globulins recovery yield was 68 %, which is in line with the faba bean results.

[0256] The method of the invention is thus suitable to pea proteins production.

Example 5: Comparison of the Pea Proteins Quality

[0257] Two tests were performed at pilot scale to compare a conventional pH metric process with the method of the invention.

[0258] Both process diagrams are presented in FIG. 1.

[0259] Applied parameters and analytical methods are summarized in Tables 10, 11 and 12.

TABLE-US-00010 TABLE 10 Materials and methods for the standard pH-metric process Step Principle Material and method Extraction Alkaline extraction of Reverse osmosis water flour proteins in a double Temperature: 55° C. jacketed tank pH adjustment, after pellets addition: 9, with NaOH Time before solid/liquid separation: 30 min Agitation: 3 blades agitator, 150 rpm Solid/liquid Separation step after Decanter Z23, Flottweg separation 1 extraction, precipitation Temperature: 55° C. and precipitate rewash Centrifugal force: 3500 to 4000 g Differential speed: 5 to 20% Impeller: 135 to 140 mm Feed flow rate: 400 kg/h Solid/liquid Only used to clarify the Disc stack centrifuge, Easy-Scale GEA separation 2 decanter supernatant Temperature: 55° C. after extraction Centrifugal force: 12 000 g Total disludge/Partial disludge: ⅕ Feed flow rate: 250 kg/h Precipitation Acidic proteins Temperature: 55° C. precipitation of the pH: 4.5 with Sulfuric acid extract supernatant Time: 15 min Precipitate Precipitate rewash in RO Reverse osmosis water rewash water at pH 4.5, followed Precipitate/water ratio: ½ by a solid/liquid separation Neutralization Precipitate neutralization pH: 6.8-7 with NaOH addition and dilution RO water addition to decrease the viscosity Heat Product stabilization Tubular heat exchanger, Actini treatment Temperature: 90° C. Holding time: 90 s Drying Product stabilization Spray dryer Inlet air temperature: 185° C. Outlet air temperature: 85° C.

TABLE-US-00011 TABLE 11 Materials and methods for the method of the invention Step Principle Material and method Acid wash Flour and acidified water Reverse osmosis water mixing followed by a solid/ Temperature: 55° C. liquid separation pH target: 4 to 4.5 with sulfuric acid Time before solid/liquid separation: 20 min Agitation: 3 blades agitator, 150 rpm Solid/liquid Separation step after Decanter Z23, Flottweg separation 1 acid wash, rinse and Temperature: 55° C. extraction Centrifugal force: 3500 to 4000 g Differential speed: 5 to 20% Impeller: 135 to 140 mm Feed flow rate: 400 kg/h Rinse 1 Pellets of acid wash and Reverse osmosis water, qs: Q.sub.AW water mixing, followed by Temperature: 55° C. a solid/liquid separation 3 blades agitator, 150 rpm Time: 10 min Rinse 2 Pellets of rinse 1 and Reverse osmosis water, qs: Q.sub.AW water mixing, followed by Temperature: 55° C. a solid/liquid separation 3 blades agitator, 150 rpm Time: 10 min Extraction Alkaline extraction of Reverse osmosis water rinsed pellets proteins in Temperature: 55° C. a double jacketed tank pH adjustment, after pellets addition: 9, with NaOH Time before solid/liquid separation: 30 min Agitation: 3 blades agitator, 150 rpm Solid/liquid Only used to clarify the Disc stack centrifuge, Easy-Scale GEA separation 2 decanter supernatant Temperature: 55° C. after extraction Centrifugal force: 12 000 g Total disludge/Partial disludge: ⅕ Feed flow rate: 250 kg/h Neutralization Extract neutralization pH: 6.8-7 with NaOH addition Heat Product stabilization Tubular heat exchanger, Actini treatment Temperature: 90° C. Holding time: 90 s Concentration Dry solid increase before Falling film evaporator, GEA spray drying Boiling temperature <50° C. Concentration target for a viscosity <100 cp Drying Product stabilization Spray dryer Inlet air temperature: 185° C. Outlet air temperature: 85° C.

TABLE-US-00012 TABLE 12 Analytical methods for proteins characterization Analyses Principle Color Evaluation with a colorimeter. Results are expressed by 3 parameters L*, a* and b *: L * (clarity), which ranges from 0 (black) to 100 (white) a * which ranges from −300 (green) axis to 299 (red). b * which ranges from −300 (blue) axis to 299 (yellow). Foaming Foaming properties were evaluated with a Foamscan (Teclis Scientific) using properties a 0.1% protein solution. Foam was formed by bubbling air in the solution at a flow rate of 200 ml/min for 30 seconds. The foam volume and its stability was then recorded during 600 seconds. Egg white is used as a reference for this test. Solubility The protein solubility was tested on protein suspensions at 2% protein content at different pH. The protein solubility was estimated by Kjeldahl method on the supernatant after centrifugation (15000 g, 10 min). Gelling Gelling capacity was measured on a DHR-2 rheometer (TA) with a 40 mm properties plate/plate geometry. A 10% protein solution at pH 7 was used. A temperature ramp was applied to the sample: heating from 25 to 90° C. with a gradient of 2° C./min, stabilization without oscillation at 90° C. for 10 minutes, cooling from 90 to 25° C. with a gradient of 2.5° C./min. A strain of 0.1% was applied during the test. G′ (storage modulus) and G″ (loss modulus) were measured Viscosity Rheological analysis was performed at 25° C. on a DHR-2 rheometer (TA) with a vane cup geometry. Different product concentrations were used. Viscosity profile was measured on a shear rate range between 0.1 s.sup.−1 and 1 000 s.sup.−1.

Results:

[0260] As shown in Table 13, there is a significant difference of color between both powders.

TABLE-US-00013 TABLE 13 Lab measurement results Data L a b Standard 89.74 −0.78 20.51 Invention 89.79 1.09 12.81

[0261] Each product was tasted as such and in 4% solution by 6 different people (naïve panel). The beany intensity of proteins obtained by the method of the invention was evaluated as significantly lower than standard pH-metric proteins.

[0262] As shown in FIG. 2, the proteins obtained by the method of the invention have a higher foaming capacity than precipitated proteins and the foam is stable over time.

[0263] The proteins solubility was also significantly improved by the method of the invention, as shown in FIG. 3 and in the Table 14 below.

[0264] Table 14 shows the solubility of a protein isolate of the invention versus commercial-type products.

[0265] Protein solubility was evaluated by solubilizing the sample in water at different pH and measuring the proportion of proteins in the supernatant after centrifugation. Samples of the protein isolate of the invention (hereinafter defined as Batch 1 and Batch 2) show much higher solubility at pH 3,7 and 8 than commercial isolate samples (hereinafter defined as Commercial 1 and Commercial 2).

TABLE-US-00014 TABLE 14 Solubility of the samples at different pH Products pH 3 pH 4 pH 5 pH 6 pH 7 pH 8 Batch 1 31 7 7 41 65 79 Batch 2 58 7 8 11 70 80 Commercial 1 12 6 6 11 18 22 Commercial 2 16 5 6 14 23 29

[0266] FIGS. 4 and 5 compare the gelling properties by thermal treatment of proteins obtained by both processes.

[0267] A solution, containing 10% of proteins obtained by the method of the invention can form a gel, contrary to standard pH-metric proteins. In this case, rheological properties are only explained by the solution viscosity.

[0268] FIG. 6 shows the viscosity evolution of a 10 % dry solid solution, according to shear stress. The viscosity of proteins of the invention solution is lower than the precipitated one, regardless the shear stress.

[0269] This viscosity was measured at different concentration for 100 s.sup.−1 shear rate. Results are presented in Table 15 and FIG. 7. At an equivalent shear rate, the solution obtained by the method of the invention has a lower viscosity than the precipitated one, for any concentration.

TABLE-US-00015 TABLE 15 Viscosity evolution according to the DS content Product Concentration Viscosity at 100 s.sup.−1 (Pa/s) Standard pH metric process  5% 0.01 Invention  5% 0.006 Standard pH metric process 10% 0.2 Invention 10% 0.04 Standard pH metric process 15% 0.8 Invention 15% 0.6

[0270] Conclusion

[0271] The pulses proteins functionality and taste are significantly improved by a process comprising acid wash followed by alkaline extraction as defined above.

[0272] These new functionalities can extend the proteins isolate application field and also reduce the production OPEX. For example, a lower viscosity allows a higher concentration before drying which can significantly decrease the energy consumption.

Example 6: Other Protein Sources

[0273] The process developed above was applied on different proteins sources. Results are summarized in Table 16.

TABLE-US-00016 TABLE 16 Other plant sources results Plant source Extraction yield Purity Red lentil 53% 88% Mojette bean 32% 82% Azuki bean 60% 84%

Example 7: Removal of Anti-Nutritional Factors: The α-Galactosides

[0274] The content of α-galactosides was measured in two samples of protein isolate of the invention (Batch 1 and Batch 2), in two commercial protein isolate samples (Commercial 1 and Commercial 2) and in a sample of protein isolate obtained by the standard pH-metric process.

TABLE-US-00017 TABLE 17 Alpha-galactosides content of samples Batch Batch Commer- Commer- pH Analysis 1 2 cial 1 cial 2 metric Raffinose (g/100 g) ND ND ND 0.22 0.26 Stachyose (g/100 g) ND ND 0.17 0.91 0.9 Verbascose (g/100 g) ND ND 0.12 0.52 0.64 Total alpha- ND ND 0.29 1.65 1.80 galactosides (g/100 g) ND: not detected - detection threshold = 0.10%
As shown in Table 17, no alpha-galactoside was detected in the two samples Batch 1 and Batch 2 (the detection threshold of the measurement method being 0,1%). On the contray, the samples Commercial 1 and 2 contain respectively 0,3 and 1,7 g/100 g of alpha-galactosides and the sample of protein isolate obtained by the standard pH metric method is 1,80 g/100 g.
As a comparison, the average alpha-galactosides content is 5 g/100 g in pea flour and 10 g 15/100 g in pea concentrate (IMPROVE data).