Use of an esterase to enhance ethyl ester content in fermentation media
Methods to prepare vegetable oil compositions having an elevated ethyl ester content are provided.
1. A method for enhancing corn oil properties from ground corn subjected to fermentation, comprising: providing an aqueous composition comprising glucose obtained by subjecting a first composition comprising 20% to 50 wt % ground corn having corn fat and a glucoamylase to conditions which produce glucose; and fermenting the aqueous composition comprising glucose in the presence of yeast under conditions which produce a second composition comprising ethanol and corn oil having a fatty acid ethyl ester content that is greater than 7% w/w based on the total weight of the corn oil portion of the second composition, wherein an amount of an exogenous esterase is added to the second composition before, during or after fermentation, or any combination thereof, wherein the exogenous esterase is in an amount that is between 0.001% and 0.4% w/w of the weight of the corn fat prior to fermentation.
2. The method of claim 1 , wherein the fatty acid ethyl ester content is greater than 10% w/w in the total weight of the corn oil portion of the second composition.
3. The method of claim 1 , wherein the fatty acid ethyl ester content is greater than 30% w/w in the total weight of the corn oil portion of the second composition.
4. The method of claim 1 , wherein the fatty acid ethyl ester content is greater than 50% w/w in the total weight of the corn oil portion of the second composition.
5. The method of claim 1 , wherein the fatty acid ethyl ester content is greater than 60% w/w in the total weight of the corn oil portion of the second composition.
6. The method of claim 1 , wherein the esterase is in an amount that is up to 0.01% w/w of the weight of the corn fat prior to fermentation.
7. The method of claim 1 , wherein the esterase is in an amount that is up to 0.04% w/w of the weight of corn fat in the aqueous composition prior to fermentation.
8. The method of claim 1 , wherein the esterase is in an amount between 0.01% and 0.4% w/w/of the weight of the corn fat after fermentation.
9. The method of claim 1 , wherein the esterase is in an amount that is 0.4% w/w of the weight of the corn fat after fermentation.
10. The method of claim 1 , wherein more than 50% of the ground corn before fermentation is capable of passing through a 0.5 mm screen.
11. The method of claim 1 , wherein the first composition further comprises an amount of fungal acid amylase.
12. The method of claim 11 , wherein the amount of the fungal acid amylase ranges from 0.1 to 10 fungal acid amylase units per gram of solids in the first composition, and the amount of the glucoamylase to solids in said first composition ranges from 0.5 to 6 glucoamylase units per gram of said solids.
13. The method of claim 1 , wherein the pH is maintained at 3-4.5 during the first half of ethanol production and at 4.5-6.0 during the second half of ethanol production.
14. The method of claim 1 , wherein the conditions for producing glucose and ethanol include a pH of from 3 to 6, and a temperature of from 25° C. to 40° C.
15. The method of claim 1 , wherein the conditions for producing glucose and ethanol include (i) a pH of from 3 to 6, and/or (ii) maintaining a glucose concentration of less than 2 weight percent after 12 hours of saccharification and fermentation.
16. The method of claim 1 , wherein said method produces at least 18 volume percent ethanol.
17. The method of claim 1 , wherein glucose is produced at a temperature of from 30° C. to 35° C., and/or a solids content in the first composition is from 25 to 45 weight percent.
18. The method of claim 1 , wherein (i) the glucose is fermented under conditions comprising an initial temperature of 35° C. which temperature is decreased during fermentation to a temperature of 30° C., and/or (ii) the glucose concentration in the aqueous composition is maintained at less than 1 weight percent after 12 hours of saccharification and fermentation, wherein the production of glucose and the fermentation of glucose to ethanol is conducted simultaneously.
19. The method of claim 1 , wherein the corn oil further comprises a lutein content of at least 50 mcg/g, a zeaxanthin content of at least 30 mcg/g, a cis-lutein/zeaxanthin content of at least 10 mcg/g, an alpha-cryptoxanthin content of at least 5 mcg/g, a beta-cryptoxanthin content of at least 5 mcg/g, an alpha-carotene content of at least 0.5 mcg/g, a beta-carotene content of at least 1 mcg/g, a cis-beta-carotene content of at least 0.1 mcg/g, an alpha-tocopherol content of at least 50 mcg/g, a beta-tocopherol content of at least 2 mcg/g, a gamma-tocopherol content of at least 300 mcg/g, a delta-tocopherol content of at least 15 mcg/g, an alpha-tocotrienol content of at least 50 mcg/g, a beta-tocotrienol content of at least 5 mcg/g, a gamma-tocotrienol content of at least 80 mcg/g, a delta-tocotrienol content of at least 5 mcg/g, or any combination thereof.
20. A method for enhancing corn oil properties from ground corn subjected to fermentation, comprising: providing an aqueous composition comprising glucose obtained by subjecting a first composition comprising ground corn having corn fat and a glucoamylase to conditions which produce glucose; and fermenting the aqueous composition comprising glucose in the presence of a yeast under conditions which produce a second composition comprising ethanol and corn oil having a fatty acid ethyl ester content that is greater than 7% w/w based on the total weight of the corn oil portion of the second composition, wherein an amount of an exogenous triacylglycerol lipase or a carboxylic ester hydrolase is added to the second composition before or during fermentation, or any combination thereof, wherein the triacylglycerol lipase or the carboxylic ester hydrolase is in an amount between 0.001% and 0.4% w/w of the weight of the corn fat prior to fermentation.