Process for the hydrolysis of starch and the continuous fermentation of the sugars obtained therefrom to provide ethanol
First Claim
1. A process for the hydrolysis of starch and the continuous fermentation of the fermentable sugars therefrom to provide ethanol which comprises:
- (a) liquefying an aqueous slurry of starch in the presence of a liquefying agent selected from the group consisting of strong acid and liquefying enzyme to provide sterile liquefied starch;
(b) saccharifying the sterile liquefied starch in a primary saccharification vessel or vessels in the presence of a saccharifying enzyme to provide an aqueous solution of sterile saccharified starch containing from about 60 to about 80 weight percent of the original starch in the form of fermentable sugar, the remaining portion of the starch being present in the form of partial hydrolysate; and
,(c) continuously fermenting the fermentable sugar, with or without partial hydrolysate therein having been previously further saccharified in a secondary saccharification vessel or vessels, in a series of fermentation vessels in which the ethanol content of the fermentation medium is progressively increased in each fermentation vessel as the fermentable sugar is consumed therein, the fermentation employing at least two different strains of ethanol-producing yeast, one of which provides a high rate of ethanol production in a fermentation medium containing a relatively low concentration of ethanol and a relatively high concentration of sugar and the other of which provides a high rate of ethanol production in a fermentation medium containing a relatively high concentration of ethanol and a relatively low concentration of fermentable sugar.
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Accused Products
Abstract
Starch is converted to ethanol by a process in which an aqueous starch slurry is hydrolyzed in sequential liquefication and saccharification steps to provide sterile saccharified starch solution containing from about 60 to about 80 weight percent of fermentable sugar based on the weight of the original starch present and the fermentable sugar is thereafter continuously converted by fermentation to dilute aqueous ethanol ("beer") in a series of agitated fermentation vessels which contain progressively more ethanol and less fermentable sugar employing at least two strains of yeast for the fermentation, one of which provides a high rate of ethanol production in a fermentation medium containing a relatively low concentration of ethanol and a relatively high concentration of fermentable sugar and the other of which provides a high rate of ethanol production in a fermentation medium containing a relatively high concentration of ethanol and a relatively low concentration of fermentable sugar.
73 Citations
36 Claims
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1. A process for the hydrolysis of starch and the continuous fermentation of the fermentable sugars therefrom to provide ethanol which comprises:
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(a) liquefying an aqueous slurry of starch in the presence of a liquefying agent selected from the group consisting of strong acid and liquefying enzyme to provide sterile liquefied starch; (b) saccharifying the sterile liquefied starch in a primary saccharification vessel or vessels in the presence of a saccharifying enzyme to provide an aqueous solution of sterile saccharified starch containing from about 60 to about 80 weight percent of the original starch in the form of fermentable sugar, the remaining portion of the starch being present in the form of partial hydrolysate; and
,(c) continuously fermenting the fermentable sugar, with or without partial hydrolysate therein having been previously further saccharified in a secondary saccharification vessel or vessels, in a series of fermentation vessels in which the ethanol content of the fermentation medium is progressively increased in each fermentation vessel as the fermentable sugar is consumed therein, the fermentation employing at least two different strains of ethanol-producing yeast, one of which provides a high rate of ethanol production in a fermentation medium containing a relatively low concentration of ethanol and a relatively high concentration of sugar and the other of which provides a high rate of ethanol production in a fermentation medium containing a relatively high concentration of ethanol and a relatively low concentration of fermentable sugar. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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36. A process for the hydrolysis of starch and the continuous fermentation of the fermentable sugars therefrom to provide ethanol which comprises:
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(a) liquefying an aqueous slurry of starch in the presence of a liquefying agent selected from the group consisting of strong acid and liquefying enzyme to provide sterile liquefied starch; (b) saccharifying the liquefied starch in a primary saccharification vessel or vessels in the presence of a saccharifying enzyme for from about two to about ten hours to provide sterile saccharified starch containing from about 60 to about 80 weight percent of the original starch in the form of fermentable sugar, the remaining portion of the starch being present in the form of partial hydrolysate; and (c) continuously fermenting the fermentable sugar, with or without partial hydrolysate therein having been previously further saccharified in a secondary saccharification vessel or vessels, in a series of fermentation vessels in which the ethanol content of the fermentation medium is progressively increased in each fermentation vessel as the fermentable sugar is consumed therein, the fermentation employing at least two different strains of ethanol-producing yeast, one of which provides a high rate of ethanol production in a fermentation medium containing a relatively low concentration of ethanol and a relatively high concentration of sugar and the other of which provides a high rate of ethanol production in a fermentation medium containing a relatively high concentration of ethanol and a relatively low concentration of fermentable sugar.
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Specification