Production of pulse protein product

Abstract

A pulse protein product having a protein content of at least about 50 wt % (N×6.25) d.b. is recovered in the processing of pulse protein source material to form pulse protein products wherein the pulse protein source is extracted in one embodiment with calcium salt solution. The resulting pulse protein solution is separated from the bulk of the residual pulse protein source and then the pulse protein solution is processed to remove finer residual solids, which are optionally washed and then dried to provide the pulse protein product. In another embodiment, the pulse protein source is extracted with water, the bulk of the residual protein source removed and the resulting pulse protein solution treated with calcium salt to precipitate phytic acid. The precipitated phytic acid and any finer residual solids remaining in solution after the initial separation step are removed from the pulse protein solution then optionally washed and dried to provide the pulse protein product.

What we claim is: 
     
         1 . A method of forming a pulse protein product having a protein content of at least 50 wt % (N×6.25) d.b., which comprises:
 (a) extracting a pulse protein source with an aqueous calcium salt solution to cause solubilization of pulse protein from the protein source and to form an aqueous pulse protein solution, 
 (b) separating the aqueous pulse protein solution from the bulk of the residual pulse protein source, 
 (c) applying a second separation step to the pulse protein solution to remove finer residual solids not removed by the initial separation step, 
 (d) alternatively from steps (b) to (c), optionally diluting the combined aqueous pulse protein solution and residual pulse protein source with about 0.1 to about 10 volumes, preferably about 0.5 to about 2 volumes of aqueous diluent then adjusting the pH of the mixture to about 1.5 to about 4.4, preferably about 2 to about 4, then separating the acidified aqueous pulse protein solution from the bulk of the residual pulse protein source and applying a second separation step to the acidified pulse protein solution to recover finer solids not removed in the initial separation step. 
 (e) optionally washing the finer solids recovered in the second separation step to remove impurities, and 
 (f) optionally drying the optionally washed finer solids recovered in the second separation step to provide the pulse protein product. 
 
     
     
         2 . The method of  claim 1  wherein the calcium salt is calcium chloride. 
     
     
         3 . The method of  claim 1  wherein the calcium salt solution has a concentration of less than about 1.0 M. 
     
     
         4 . The method of  claim 3  wherein the concentration of the calcium salt solution is about 0.10 to about 0.15 M. 
     
     
         5 . The method of  claim 1  wherein said extraction step is effected at a temperature of about 1° to about 100° C., preferably about 15° to about 65° C., more preferably about 20° to about 35° C. 
     
     
         6 . The method of  claim 1  wherein said extraction with aqueous calcium solution is conducted at a pH of about 4.5 to about 11, preferably about 5 to about 7. 
     
     
         7 . The method of  claim 1  wherein said aqueous pulse protein solution has a protein concentration of about 5 to 50 g/L, preferably about 10 to about 50 g/L. 
     
     
         8 . The method of  claim 1  wherein said aqueous calcium salt solution contains an antioxidant and/or an anti-foamer. 
     
     
         9 . The method of  claim 1  wherein the solids recovered in the second separation step are washed in at least one washing step with between about 1 and about 20, preferably about 1 to about 10 volumes of water. 
     
     
         10 . The method of  claim 9  wherein said at least one washing step is effected using acidified water. 
     
     
         11 . The method of  claim 10  wherein the acidified water has a pH of about 4.2 to about 4.8. 
     
     
         12 . The method of  claim 1  wherein the pulse protein product has a protein concentration of at least about 60 wt % (N×6.25) d.b. 
     
     
         13 . The method of  claim 12  wherein said pulse protein product has a protein concentration of at least about 65 wt % (N×6.25) d.b. 
     
     
         14 . A method of forming a pulse protein product having a protein content of at least about 50 wt % (N×6.25) d.b., which comprises:
 (a) mixing a pulse protein source with water to form a slurry, 
 (b) separating the aqueous pulse protein solution from the bulk of the other components of the slurry, 
 (c) adding a calcium salt to the aqueous pulse protein solution to precipitate calcium phytate, 
 (d) applying a second separation step to the calcium treated pulse protein solution to recover the precipitate as well as any finer solids not removed in the initial separation step (b), 
 (e) alternatively from step (d), optionally diluting the calcium treated pulse protein solution with about 0.1 to about 10 volumes, preferably about 0.5 to about 2 volumes of aqueous diluent and then adjusting the pH of the mixture to about 1.5 to about 4.4, preferably about 2 to about 4, then applying a second separation step to the acidified calcium treated pulse protein solution to recover the precipitate as well as any finer solids not removed in the initial separation step (b), (f) optionally washing the solid materials recovered in the second separation step to remove impurities, and 
 (g) optionally drying the optionally washed solids recovered in the second separation step. 
 
     
     
         15 . The method of  claim 14  wherein the water extraction step is effected for about 1 to about 60 minutes at a temperature of about 1° to about 70° C., preferably about 15° to about 65° C., more preferably about 20° to about 35° C. 
     
     
         16 . The method of  claim 14  wherein the water extraction is carried out at a pH of about 4.5 to about 11, preferably about 5 to about 7. 
     
     
         17 . The method of  claim 14  wherein the aqueous pulse protein solution has a protein concentration of less than 250 g/L, preferably about 5 to about 100 g/L, more preferably about 5 to about 50 g/L. 
     
     
         18 . The method of  claim 14  wherein the calcium salt is added in the form of an aqueous calcium salt solution. 
     
     
         19 . The method of  claim 14  wherein the calcium salt is added in an amount to provide a calcium treated solution having a calcium salt concentration of less than about 1.0 M, preferably between about 0.05 M and about 0.15 M. 
     
     
         20 . The method of  claim 19  wherein the calcium treated protein solution is mixed for up to about 60 minutes, preferably about 15 to about 30 minutes at a temperature of about 1° to about 100° C., preferably about 15° to about 65° C., more preferably about 20° to about 35° C. 
     
     
         21 . The method of  claim 14  wherein the solids recovered in the second separation step are washed in at least one washing step with between about 1 and about 20, preferably about 1 to about 10 volumes of water. 
     
     
         22 . The method of  claim 21  wherein said at least one washing step is effected using acidified water. 
     
     
         23 . The method of  claim 22  wherein the acidified water has a pH of about 4.2 to about 4.8. 
     
     
         24 . The method of  claim 14  wherein the pulse protein product has a protein concentration of at least about 60 wt % (N×6.25) d.b. 
     
     
         25 . The method of  claim 24  wherein said pulse protein product has a protein concentration of at least about 65 wt % (N×6.25) d.b. 
     
     
         26 . A pulse protein product having a protein content of at least about 50 wt % (N×6.25) d.b. and at least one parameter selected from the group consisting of:
 (a) a phytic acid content of at least 2.5 wt % d.b., 
 (b) a crude fibre content of less than about 1.5 wt % d.b., 
 (c) a solubility of less than about 15 wt % over a pH range of about 3 to about 6 when solubility is determined by the protein method described in Example 5, 
 (d) a solubility of less than about 25 wt % over a pH range of about 3 to about 6 when solubility is determined by the pellet method described in Example 5, 
 (e) a water binding capacity of less than about 2.5 ml/g, and 
 (f) an oil binding capacity of less than about 2 ml/g. 
 
     
     
         27 . The pulse protein product of  claim 26  having a protein content of at least 60 wt %. 
     
     
         28 . The pulse protein product of  claim 26  which is a concentrate having a protein content of at least about 65 wt %.