Methods of producing vegetable oils with low minerals, metals, or other contaminants
The present disclosure describes methods for reducing the content of minerals, metals, ions, and/or other undesirable contaminants in vegetable oil, such as corn oil, obtained from fermentation of ground vegetable material. In one aspect, the methods herein produce distiller's corn oil having low amounts of minerals, metals, ions, and/or other contaminants rendering the corn oil more suitable for various further uses, such as biofuel production, with little to no additional refining.
1. A process for reducing the content of ions in a vegetable oil obtained from fermentation of ground vegetable material, the process comprising:
fermenting a sugar obtained from a ground vegetable material to produce ethanol in a composition that further includes one or more of water, residual ground vegetable material, and vegetable fat;
adding about 0.001 to about 0.5% w/w of an exogenous esterase based on the total weight of the vegetable fat before, during, or after the fermenting; and
isolating vegetable oil from a portion of the composition in a manner effective to produce an isolated vegetable oil having ions but no more than about 20 ppm of ions.
2. The process for reducing the content of metal ions in a vegetable oil obtained from fermentation of ground vegetable material of claim 1 , wherein the isolating includes combining at least a portion of the vegetable fat from the composition with water to form a mixture and recovering the isolated vegetable oil from the mixture by gravity separation.
3. The process for reducing the content of metal ions in a vegetable oil obtained from fermentation of ground vegetable material of claim 2 , wherein the gravity separation is through one or more settling tanks.
4. The process for reducing the content of metal ions in a vegetable oil obtained from fermentation of ground vegetable material of claim 2 , wherein about 0.1 to about 30% w/w water is combined with the portion of vegetable fat.
5. The process for reducing the content of metal ions in a vegetable oil obtained from fermentation of ground vegetable material of claim 2 , wherein about 2 to about 20% w/w water is combined with the portion of vegetable fat.
6. The process for reducing the content of metal ions in a vegetable oil obtained from fermentation of ground vegetable material of claim 2 , wherein the isolating further includes separating the portion of vegetable fat from the composition into an oil fraction and an aqueous portion by applying a first centrifugal force to the portion of vegetable fat, wherein the oil fraction includes the portion of vegetable fat; adjusting a pH of the oil fraction to form a pH adjusted oil fraction; and separating the pH adjusted oil fraction into an oil composition and a second aqueous portion by applying a second centrifugal force, wherein the oil composition includes the portion of vegetable fat.
7. The process for reducing the content of metal ions in a vegetable oil obtained from fermentation of ground vegetable material of claim 5 , wherein the pH is adjusted to a range of about 3 to about 7.
8. The process for reducing the content of metal ions in a vegetable oil obtained from fermentation of ground vegetable material of claim 5 , wherein the pH is adjusted to a range of about 3.5 to about 6.
9. The process for reducing the content of metal ions in a vegetable oil obtained from fermentation of ground vegetable material of claim 5 , wherein the pH is adjusted to a range of about 7 to about 10.
10. The process for reducing the content of metal ions in a vegetable oil obtained from fermentation of ground vegetable material of claim 1 , wherein the isolating further includes separating the portion of vegetable fat of the composition into an oil fraction and an aqueous portion through addition of a demulsifying agent, wherein the oil fraction includes the portion of vegetable fat.
11. The process for reducing the content of metal ions in a vegetable oil obtained from fermentation of ground vegetable material of claim 10 , wherein the demulsifying agent is selected from silica, silicates, lecithin, wax, polyethylene, resins, ethyoxylated fatty mono-, di-, or triglycerides or ethoxylated saccharide esters, polyglycerols, polyglycol, polyadduct of polyglycol and alkenyl succinic acid anhydride, polyester of polyglycol, alkenyl succinic anhydride polyester, block copolymer of propylenoxide and ethylenoxide, polyglycerol, polyester of poly-a-olefin phenol-formaldehyde resins, epoxy resins, polyethyleneimines, polyamines, di-epoxides, polyols, dendrimers thereof, or combinations thereof.
12. The process for reducing the content of metal ions in a vegetable oil obtained from fermentation of ground vegetable material of claim 2 , wherein the gravity separation is for about 10 minutes to about 24 hours and at a mixture temperature of about 0° C. to about 100° C.
13. The process for reducing the content of metal ions in a vegetable oil obtained from fermentation of ground vegetable material of claim 12 , wherein the gravity separation is for about 1 to about 16 hours.
14. The process for reducing the content of metal ions in a vegetable oil obtained from fermentation of ground vegetable material of claim 13 , wherein the mixture temperature is about 50 to about 80° C.
15. The process for reducing the content of metal ions in a vegetable oil obtained from fermentation of ground vegetable material of claim 2 , wherein the gravity separation is for about 1 to about 24 hours and the mixture is maintained at a temperature of about 50 to about 80° C. for about 4 to about 24 hours of the gravity separation.
16. The process for reducing the content of metal ions in a vegetable oil obtained from fermentation of ground vegetable material of claim 1 , wherein the isolating includes recovering the isolated vegetable oil from the mixture by gravity separation.
17. The process for reducing the content of metal ions in a vegetable oil obtained from fermentation of ground vegetable material of claim 16 , wherein the gravity separation is for about 1 to about 24 hours and the mixture is maintained at a temperature of about 50 to about 80° C. for about 4 to about 24 hours of the gravity separation.
18. The process for reducing the content of metal ions in a vegetable oil obtained from fermentation of ground vegetable material of claim 1 , wherein the fermenting is at a pH of about 3 to about 6.
19. The process for reducing the content of metal ions in a vegetable oil obtained from fermentation of ground vegetable material of claim 18 , wherein the fermenting is at a temperature of about 25° C. to about 40° C.
20. The process for reducing the content of metal ions in a vegetable oil obtained from fermentation of ground vegetable material of claim 18 , wherein the exogenous esterase is added during the fermenting.
21. The process for reducing the content of metal ions in a vegetable oil obtained from fermentation of ground vegetable material of claim 1 , wherein the isolated vegetable oil has about 50 to about 95% less ions than an isolated vegetable made by the same process but without the exogenous esterase.
22. The process for reducing the content of metal ions in a vegetable oil obtained from fermentation of ground vegetable material of claim 1 , wherein the ions are selected from one or more of from lithium, sodium, magnesium, potassium, calcium, phosphorus, or combinations thereof.
23. The process for reducing the content of metal ions in a vegetable oil obtained from fermentation of ground vegetable material of claim 1 , wherein the isolated vegetable oil has no more than about 10 ppm of ions.
24. The process for reducing the content of metal ions in a vegetable oil obtained from fermentation of ground vegetable material of claim 1 , wherein the isolated vegetable oil has no more than about 20 ppm of chlorides.