Oilseed processing
Crushed and de-fatted oilseed is extracted with water at neutral, mildly basic or mildly acidic pH; and is filtered. The filter media allows passage of small fragments of solid cell meat into the filtrate. The filtrate is treated with a base to increase pH to over pH 9, and solids are separated out. Protein is separated from other constituents of the liquid and concentrated, for example by heat-induced or isoelectric precipitation and/or ultrafiltration. The remaining liquid is rich in sugars. The process results in one or more protein products suited for human or animal food ingredients or for production of cosmetics, a sugar rich product suitable for fermentation or use as a feed ingredient, and a fiber-protein animal feed ingredient.
1. A process of treating detailed oilseed, which comprises:
(a) slurrying the detailed oilseed in water at a pH of 3–9 to create a slurry;
(b) separating the slurry into a first solid product and a first predominantly liquid fraction, and
(c) adding sufficient alkaline compound to the first predominantly liquid fraction to increase its pH to in excess of pH 9, whereby a second solid product precipitates from said first predominantly liquid fraction, leaving an alkaline second liquid fraction.
2. A process as claimed in claim 1 , in which the step of slurrying is carried out at a pH of 7–9.
3. A process as claimed in claim 2 , in which said first solid product comprises solids unable to pass through a screen having openings of 25 microns, but able to pass through a screen having openings of 2500 microns.
4. A process as claimed in claim 2 , in which sufficient alkaline compound is added to the predominantly liquid fraction to increase the pH of said liquid fraction to a pH in the range 11–12.
5. A process as claimed in claim 4 , in which the alkaline compound is CaO.
6. A process as claimed in claim 4 , in which the alkaline compound is Ca(OH) 2 .
7. A process as set out in claim 2 , in which the slurry is heated to 50° C.–95° C. and is agitated for from 5 minutes to 2 hours before it is separated into said first solid product and said predominantly liquid fraction.
8. A process as claimed in claim 2 , including the additional steps of:
(d) separating out said precipitate from the predominantly liquid fraction, whereby to obtain a second solid product and a second liquid fraction,
(e) adding water and a sufficient amount of an acidic compound to said second solid product, to acidify the second solid product to a pH 1–5, whereby a portion of said second solid product dissolves in the water to form a third liquid and the remainder of the second solid product does not dissolve, and
(f) precipitating protein from said alkaline second liquid fraction, whereby to obtain a fourth solid precipitate which is rich in protein and a fourth liquid which remains after the precipitation.
9. A process as claimed in claim 8 , in which the fourth liquid is ultrafiltered to yield a protein rich retentate and a sugar-rich permeate.