Subcritical water assisted oil extraction and green coal production from oilseeds
Provided herein are methods of optimizing energy recovery from oilseeds. The methods disclosed provide at least the ability to swell oilseeds and disrupt the cell walls (hulls) without changing the functionality and quality of oil; the process integration of removing the impurities from oilseeds, oil extraction, protein hydrolysis, and green coal production to maximize the energy recovery in the form of crude oil, polypeptides, oligopeptides, amino acids, and/or green coal from oilseeds; and heat integration during processing stages including subcritical water pretreatment, oil extraction, subcritical water post-treatment, and subcritical water carbonization to minimize the process heat requirement.
1. A method of recovering polypeptides, oligopeptides, amino acids, or combinations thereof from an oilseed, the method comprising:
pretreating whole oilseeds with subcritical water at a pretreatment temperature to remove impurities, contaminants, or both;
separating pretreated oilseeds from a pretreated liquid phase; and
extracting proteins and undergoing protein hydrolysis to produce polypeptides, oligopeptides, amino acids, or combinations thereof from the pretreated oilseeds using an organic solvent to produce a solid phase;
extracting proteins and undergoing protein hydrolysis to produce polypeptides, oligopeptides, amino acids, or combinations thereof from the solid phase using subcritical water at a post-treatment temperature.
2. The method of claim 1 , wherein the pretreatment temperature is between about 180° C. and 220° C.
3. The method of claim 1 , wherein pretreating occurs for a period between 5 minutes and 60 minutes.
4. The method of claim 1 , wherein the pretreating occurs at a pressure of between about 150 and 500 psi.
5. The method of claim 1 , wherein the separation comprises the use of machine press, centrifugation, evaporation, vacuum filtration, or combinations thereof.
6. The method of claim 1 , wherein the whole oilseeds are one or more of cotton seeds, rapeseeds, mustard seeds, jathopha seeds, sunflower seeds, safflower seeds, tobacco seeds, sesame seeds, soybeans seeds, flaxseeds, peanuts, and canola seeds.
7. The method of claim 1 , wherein the proteins are selected from albumins, globulins, prolamins, and combinations thereof.
8. The method of claim 1 , wherein the organic solvent is selected from n-hexane, ethanol, methanol, chloroform, acetone, dichloromethane, and petroleum ethers.
9. The method of claim 1 , further comprising extracting polypeptides, oligopeptides, amino acids, or combinations thereof from the solid phase with subcritical water at a post-treatment temperature.
10. The method of claim 9 , wherein the post-treatment temperature is between about 190° C. and 240° C.
11. The method of claim 9 , wherein post-treatment occurs for a period of between about 10 minutes and 40 minutes.
12. The method of claim 9 , wherein the post-treatment pressure is between about 300 and 900 psi.
13. The method of claim 9 , further comprising producing green coal from the solid phase with subcritical water carbonization of the solid phase at a carbonization temperature.
14. The method of claim 13 , wherein the whole oilseeds are one or more of cotton seeds, rapeseeds, mustard seeds, jathopha seeds, sunflower seeds, safflower seeds, tobacco seeds, sesame seeds, flaxseeds, peanuts, and canola seeds.
15. The method of claim 13 , wherein the carbonization temperature is between about 220° C. and 300° C.
16. The method of claim 13 , wherein the carbonation pressure is between about 900 and 1500 psi.
17. The method of claim 13 , wherein the carbonization reaction time is between about 5 and 60 minutes.