Patent Description:
In the US, commercial corn-based ethanol production has been accomplished both by wet milling and dry grinding. The dry grind process has a lower capital investment but suffers from low coproduct value. In the dry grind process, corn is not separated into individual fractions. Instead, the whole corn is processed for <NUM> (<NUM>st Generation) ethanol production. As a result, non-fermentables, such as germ, protein, vitamins, minerals, and fiber are carried through the fermentation process. These non-fermentable co-products are recovered as feedstock for animals, commonly known as dried distiller's grains with solubles (DDGS), which often returns value less than raw corn. In addition to DDGS, distiller's corn oil (DCO) is another key co-product from corn ethanol production. DCO has played a significant role in sustaining the economic viability of the corn industry during periods of weakness in ethanol prices. There exists a need for processes that provide for enhanced recovery of valuable co-products of corn ethanol production such as DDGS and DCO.

The value of DDGS as an animal feed is largely dependent on its protein content. Higher protein content provides greater nutritional benefit for animals. In addition, it is desirable in some circumstances to have a relatively low fat content. While fat in the DDGS enhances the energy density of the feed, high fat content can negatively impact milk production in DDGS-fed cattle and meat texture in DDGS-fed swine. Thus, there also exists a need for processes that enhance the value of DDGS and other co-products of ethanol production processes as an animal feed.

<CIT> relates to an animal feed composition comprising <NUM>-<NUM> wt. % of a high protein distillers dried grains (DDG) produced by recovering insoluble solids remaining after enzymatic hydrolysis and alcoholic fermentation of starch and non-starch carbohydrates. The high protein DDG has <NUM> - <NUM> wt. % protein, <NUM> - <NUM> wt. % fat, and less than <NUM> wt.

<CIT> describes a process for high solids fermentation to produce ethanol from a biomass feedstock. Whole stillage is separated into a distiller's grain and thin stillage. The dried distiller's grain comprises <NUM>-<NUM> wt. % crude protein, <NUM>-<NUM> wt. % crude fat, <NUM>-<NUM> wt. % crude fibre, and <NUM>-<NUM> wt.

<NPL>) presents three configurations for processing dry grind distillers' grains. The flow scheme involves a dry grind process with recycle of distillers grains (wet cake) to fermentation (scheme a), recycle to liquefaction, co-fermentation (scheme b), and separate hexose and pentose fermentations (scheme c).

This disclosure includes compositions and methods that meet the needs identified above. In particular, processes are disclosed that use co-products of ethanol production processes as a feedstock for the production of additional ethanol, DCO, and enhanced co-products. The enhanced co-products have a higher value than conventional co-products due to a higher protein content and reduced fat content, among other properties. The process can also improve the economic performance of the corn ethanol production process, as it increases the total yield of ethanol and DCO from corn feedstock.

In accordance with the present invention, there is provided a method of processing fiber-containing co-products of an alcohol production process, the method comprising (a) contacting polysaccharide fibers present in a mixture comprising one or more co-products of an alcohol production process with an α-hydroxysulfonic acid to hydrolyze at least a portion of the polysaccharide fibers, thereby generating fermentable sugars and releasing oil from the polysaccharide fibers, wherein the one or more co-products of an alcohol production process comprise one or more of the following: (i) wet distiller's grains; (ii) thin stillage; (iii) whole stillage; and (iv) gluten feed; wherein the concentration of α-hydroxysulfonic acid is <NUM> to <NUM>% by weight of the mixture, and the temperature of the mixture is <NUM> to <NUM>; (b) increasing the pH of the mixture by adding a base to the mixture; (c) contacting polysaccharide fibers present in the mixture with enzymes to hydrolyze the polysaccharide fibers, thereby generating additional fermentable sugars and releasing further oil from the polysaccharide fibers, wherein the temperature of the mixture is <NUM> to <NUM>; (d) incubating the mixture with yeast under anaerobic conditions to produce alcohol by fermenting fermentable sugars produced in steps (a) and (c), wherein the temperature of the mixture is <NUM> to <NUM>; (e) distilling the mixture to remove alcohol from the mixture, thereby producing an alcohol-containing distillate and enhanced whole stillage; (f) removing released oil from the fermented mixture produced in step (d) and/or from the enhanced whole stillage produced in step (e); (g) separating the enhanced whole stillage to produce enhanced wet distiller's grains and enhanced thin stillage; and (h) drying the enhanced wet distiller's grains to remove moisture, thereby producing enhanced dried distiller's grains (E-DDG) having a total protein content of at least <NUM>% on a dry weight basis and a total fat content of no more than <NUM>% on a dry weight basis.

In some embodiments, the alcohol production process that generates the co-products used in step (a) of the method is a process of producing ethanol from dry-milled corn or wet-milled corn. In some embodiments, the mixture of step (a) has a water content of <NUM> to <NUM>% by weight.

In some embodiments, the α-hydroxysulfonic acid is <NUM> to <NUM>% by weight of the mixture in step (a). In some embodiments, the method further comprises removing at least a portion, preferably at least <NUM>%, of the α-hydroxysulfonic acid from the mixture before step (c). In some embodiments, the removed α-hydroxysulfonic acid is re-used to hydrolyze polysaccharide fibers in another batch of the mixture of step (a).

In some embodiments, the base added in step (b) is magnesium hydroxide, ammonia, slake lime, calcium hydroxide, or potassium hydroxide.

In some embodiments, at least <NUM>% of the fermentable sugar monomers in the mixture are consumed in step (d). In some embodiments, after step (d) the ethanol concentration is at least <NUM>/L.

In some embodiments, step (f) further comprises separating the oil from the fermented mixture using a gravity settler, allowing the fermented mixture to sit without agitation to allow the oil to separate from the fermented mixture, centrifuging the enhanced whole stillage to separate the oil from the enhanced whole stillage, allowing the enhanced whole stillage to sit without agitation to allow the oil to separate from the enhanced whole stillage, or a combination thereof. In some embodiments, the weight of the oil removed in step (f) is at least <NUM>% of the total weight of the mixture before removal of the oil.

In some embodiments, the enhanced wet distiller's grains have a moisture content of no more than <NUM>% by weight. In some embodiments, the enhanced thin stillage has a moisture content of <NUM> to <NUM>% by weight, a crude protein content of at least <NUM>% on a dry weight basis, or any combination thereof. In some embodiments, the method further comprises drying the enhanced thin stillage produced in step (g) to produce an enhanced syrup having a moisture content of <NUM> to <NUM>% by weight and adding the enhanced syrup to the enhanced wet distiller's grains before or during the drying of step (h). In some embodiments, the enhanced thin stillage produced in step (g) is filtered through one or more membranes to produce a protein-enriched rententate with a reduced sulfur content as compared to the enhanced thin stillage. In some embodiments, the protein-enriched retentate is dried to form a protein-enriched enhanced syrup. In some embodiments, the enhanced thin stillage produced in step (g) is mixed with an organic solvent to precipitate proteins in the enhanced thin stillage. In some embodiments, the organic solvent is ethanol, THF, or acetone. In some embodiments, the ratio of solvent to enhanced thin stillage is between <NUM>: <NUM> and <NUM>: <NUM>, or is preferably about <NUM>: <NUM>. In some embodiments, the precipitate is separated from the supernate and mixed with the enhanced wet distiller's grains produced in step (g) either before or during step (h). In some embodiments, the E-DDG produced in step (h) has: a moisture content of <NUM> to <NUM>% by weight; a total protein content of at least <NUM>% on a dry weight basis, preferably at least <NUM>% on a dry weight basis; a fiber content of less than <NUM>% on a dry weight basis;
a starch content of less than <NUM>% on a dry weight basis; an ash content of less than <NUM>% on a dry weight basis; or a combination thereof.

In some embodiments in which oil is separated from the fermentation broth before distillation is performed, the separation is achieved by a gravity settler, and alternative subsequent processing steps are performed. In such embodiments, the decanted oil is flashed to remove any water and/or ethanol present in the oil, and the water and/or ethanol are recovered and combined with the heavy liquid fraction from the settler and directed to the distillation column. The combined fermentation broth is then distilled, and the enhanced whole stillage from the distillation is directed to a multi-stage evaporator to produce a syrup, which is further dried to produce E-DDGS. In some embodiments, the syrup is dried by spray drying. These processing steps may also be used in any of the other embodiments disclosed herein.

Also disclosed is a method of processing fiber-containing co-products of an alcohol production process, the method comprising: (a) contacting polysaccharide fibers present in a mixture comprising wet distiller's grains with α-hydroxyethane sulfonic acid at a concentration of <NUM> to <NUM>% by weight of the mixture, preferably <NUM>% by weight, at a temperature of <NUM> to <NUM>, preferably <NUM>, for a duration of at least <NUM> minutes to hydrolyze at least a portion of the polysaccharide fibers, thereby generating fermentable sugars and releasing oil from the polysaccharide fibers; (b) increasing the pH of the mixture to <NUM> to <NUM>, preferably <NUM>, by adding a base to the mixture; (c) contacting polysaccharide fibers in the mixture with enzymes at a concentration of from <NUM> to <NUM>% on a dry weight basis, preferably <NUM>%, at a temperature from <NUM> to <NUM>, preferably <NUM>, to hydrolyze the polysaccharide fibers, thereby generating additional fermentable sugars and releasing further oil from the polysaccharide fibers; (d) incubating the mixture with yeast under anaerobic conditions for at least <NUM> hours, preferably at least <NUM> hours, to produce alcohol by fermenting fermentable sugars produced in steps (a) and (c), wherein the temperature of the mixture is <NUM> to <NUM>, preferably <NUM>; (e) distilling the mixture to remove alcohol from the mixture, thereby producing an alcohol-containing distillate and enhanced whole stillage; (f) removing released oil from the fermented mixture produced in step (d) and/or from the enhanced whole stillage produced in step (e); (g) separating the enhanced whole stillage to produce enhanced wet distiller's grains and enhanced thin stillage; and the drying of step (h) continues until the moisture content of the E-DDG is <NUM> to <NUM>% by weight, and the E-DDG produced in step (h) preferably has one or more of the following properties: a total protein content of at least <NUM>% on a dry weight basis; a fiber content of less than <NUM>% on a dry weight basis; a starch content of less than <NUM>% on a dry weight basis; and an ash content of less than <NUM>% on a dry weight basis. When wet distiller's grains are used as the feed for step (a), the total protein content of the E-DDG produced in step (h) can be at least <NUM>% or at least <NUM>% on a dry weight basis.

The terms "a" and "an" are defined as one or more unless this disclosure explicitly requires otherwise.

The terms "substantially," "about," and "approximately" are defined as largely but not necessarily wholly what is specified - and includes what is specified; e.g., substantially <NUM> degrees includes <NUM> degrees and substantially parallel includes parallel - as understood by a person of ordinary skill in the art. In any disclosed embodiment, the terms "about" and "approximately" may be substituted with "within [a percentage] of" what is specified, where the percentage includes <NUM>, <NUM>, <NUM>, and <NUM> percent.

Any embodiment of any of the apparatuses, systems, and methods can consist of or consist essentially of - rather than comprise/include/have - any of the described steps, elements, and/or features. Thus, in any of the claims, the term "consisting of" or "consisting essentially of" can be substituted for any of the open-ended linking verbs recited above, in order to change the scope of a given claim from what it would otherwise be using the open-ended linking verb. For example, the methods of introducing substances into cells disclosed herein can "comprise," "consist essentially of," or "consist of" particular components, compositions, ingredients, etc. disclosed throughout the specification.

The feature or features of one embodiment may be applied to other embodiments, even though not described or illustrated, unless expressly prohibited by this disclosure or the nature of the embodiments. Some details associated with the embodiments described above and others are described below.

Embodiments disclosed herein involve production of ethanol and various co-products, such as enhanced dried distiller's grains (E-DDG) and distiller's corn oil (DCO), using as a feedstock wet distiller's grains and/or other co-products of a previously-performed corn ethanol production process. The previous production process can use either dry milling or wet milling of corn as an initial step in corn ethanol production.

In contrast to wet milling, which produces a range of co-products from the various constituents of the corn kernel before ethanol production is carried out, dry milling is focused on converting the starch in whole corn kernels to alcohol and recovering post-fermentation co-products as protein for animal feed. The primary difference between wet and dry milling is in the initial grain processing step. In wet milling, corn is steeped and then separated into its component parts, which are recovered prior to fermentation. In dry milling, the corn is ground into meal and fermented without prior separation of component parts.

In the first step of a typical dry milling process, the corn is hammer-milled and ground to a fine powder called meal. Corn meal is mixed with water, which can be derived from corn grains, makeup water, recycled water, water condensate from evaporators, and/or CO<NUM> scrubber water, producing corn mash. α-amylase is added to the slurry mixer to start the degradation of starch to dextrin. Corn slurry is then cooked using a hydro-heater. Steam enters the cooking system to heat the slurry and a pressure drop is applied to facilitate the mechanical shearing of starch molecules. The slurry is then heated under pressure, which further breaks down fiber and reduce the bacterial levels in the corn mash (<NPL>)).

The cooked mash is liquefied, which partially converts the gelatinized starch to soluble dextrin, decreasing the viscosity significantly. Additional α-amylase is added to this step since the cooking process denatures most of the previously-added enzymes. The yeast propagation process starts aerobically to induce cell growth in the yeast tank. Simultaneously, the fermentation tanks are filled with liquefied mash, and gluco-amylase is added to the process to bring the process of saccharification, i.e., to hydrolyze dextrin to fermentable sugars. When the propagated yeast is ready, it is added to the fermenter and during this step, yeast ferments glucose to ethanol and CO<NUM>. A typical corn-to-ethanol plant has three or more fermenters operating in a batch mode in staggered cycles. This anaerobic process is operated at temperatures ranging usually from <NUM> to <NUM> since higher temperatures can decrease the yeast metabolic activity. CO<NUM> from the process is removed through scrubbers. The fermented mash, known as "beer," may contain approximately <NUM> v% of ethanol along with non-fermentable solids from the corn and yeast cells. The beer is pumped into continuous distillation columns, where ethanol is separated from the solids and most of the water as an azeotrope. The first distillation columns produce ethanol in concentrations normally ranging from <NUM> to <NUM> v%, and water from this process is usually recycled to the α-amylase tank. The ethanol-water mixture is distilled up to the <NUM>% azeotropic-concentration point on the second column, where it is sent to a molecular-sieve TSA system, producing anhydrous ethanol.

In a typical dry-mill plant, co-product recovery starts with post-processing of the bottom fraction of ethanol distillation from the fermented mash, which is referred to as "whole-stillage. " Whole stillage typically contains <NUM>-<NUM>% of total solids, and is a hot, mildly acidic, and viscous fluid, with limited shelf life. Whole stillage is usually dried for easier handling, storage, and end use. The most common practice to handle whole stillage is to transform it into a stable product using a series of unit operations, first using a centrifuge for the solid-liquid separation. The solid fraction from this separation is known as "wet distiller's grains" (WDG) or commonly "wet-cake," and the liquid fraction, which typically contains about <NUM>-<NUM>% of moisture, is referred to as "thin stillage. " Thin stillage is typically dried to a moisture content of <NUM>-<NUM>% to produce "condensed distiller's solubles" (CDS), or commonly "syrup. " A portion of the syrup is often combined with wet-cake to produce a nutrient-rich material, which is dried in order to produce "dried distiller's grains with solubles" (DDGS) (<NPL>)).

A significant portion of thin stillage can be "back-set" as the source of water and nutrients to the cooking step, which yields water and thermal energy savings. This backsetting is often coupled with a series of anaerobic digesters. Thin stillage by itself has been recognized as an excellent energy and protein source for several different animals, such as growing and lactating cattle. It is therefore fed to animals in combination with poor quality feeds, where it acts as an energy and protein supplement. In well balanced diets, thin stillage can improve feed efficiency by reducing dry matter intake.

In addition to DDGS, distiller's corn oil (DCO) is another key co-product that has played a significant role in sustaining the economic viability of the industry during periods of weakness in ethanol prices. DCO is different from the crude corn oil that is obtained from the corn wet milling process. Crude corn oil is marketed for food grade corn oil, and DCO is targeted for biodiesel and animal feed purposes. DCO can be extracted from thin stillage. The energy required to create this DCO is shown to be much lower than that of a wet-mill plant, as it is done post-fermentation and is expected to require much less capital and lower operating costs due to the fermentation conditions applied, thus allowing it to be a viable feedstock for biodiesel production. DCO recovery in dry-mill ethanol plants is usually accomplished by placing the separation step within the thin stillage evaporators. Thin stillage is sent to a first evaporator, DCO is recovered, and then defatted thin stillage is further concentrated to syrup. The utilization of separation aids, such as precipitated and hydrophobic silica, has been described as a further alternative to decrease the need for additional separation units, which can be added on the inlet or outlet of an evaporator (<CIT>). The recovery of oil from thin stillage after evaporation using a disk stack centrifuge has also been disclosed (<CIT>). This process includes heating the thin stillage at a temperature ><NUM> at a pressure greater than its vapor pressure, followed by a cooling phase which helps to separate the oil from thin stillage. Continuous centrifuges, three-phase decanter centrifuges, and disk stack centrifuges can be used to separate DCO; disk stack centrifuges are particularly suited to removing bound and emulsified oil (<NPL>)).

While a high oil content in DDG increases the energy density of DDG for feeding livestock, it can also negatively impact milk production by dairy cattle and texture of pork in DDG-fed swine. Therefore, DDG with reduced fat content, which can be produced using methods disclosed herein, can improve the quality of animal feed. This can be accomplished by liberating and recovering oil present in the fibers of conventional DDG. This has the advantage of reducing the fat content in E-DDG, as well as producing additional DCO.

A <NUM> ethanol facility produces bioethanol by fermenting sugars formed from easily hydrolysable starch in corn, as described above. Embodiments of the methods disclosed herein take advantage of the cellulosic sugars hidden in the corn kernel fiber for production of cellulosic ethanol and enhanced co-products, such as E-DDG. Corn kernels consist mainly of starch, but they also contain <NUM>-<NUM>% fiber, as well as some protein and fat. The fiber consists of cell walls that contain cellulose and hemicellulose, together with a small amount of lignin. It also contains some starch. The corn kernel fiber is present in co-products of <NUM> corn ethanol processes such as whole stillage, wet distiller's grains, and dried distiller's grains. To produce cellulosic ethanol from the fiber present in such co-products, cellulose and hemicelluloses must be broken down into fermentable sugars. The primary obstacle to the usage of the fiber in the wet cake is an expensive "pretreatment" step to release these sugars and make the cellulose and other polysaccharides in the feedstock accessible to enzymatic hydrolysis. One potential pretreatment strategy is dilute mineral acid hydrolysis. The conditions of a successful pretreatment in dilute acid hydrolysis are determined by a combination of three factors: time, temperature, and acid concentration. Increased temperatures increase the rate of breakdown of fibers and release of cellulose, but also result in increased loss of sugars and proteins to degradation products and fouling. Also, increasing acid concentration (to allow for lower temperature) comes at the expense of the acid employed and neutralized salts in downstream equipment. An effective solution to this dilemma is provided by the use of reversible α-hydroxysulfonic acids for pre-treatment, as described in <CIT>. This pretreatment is effective at relatively low temperatures, for example, about <NUM> to <NUM>, and the α-hydroxysulfonic acids are reversible and can readily be removed from the pretreatment slurry and recycled.

α-Hydroxysulfonic acids appear to be as strong as, if not stronger than, HCl since an aqueous solution of the adduct has been reported to react with NaCl, freeing the weaker acid, HCl. The reversible acid can generally be prepared by reacting at least one carbonyl compound or precursor of carbonyl compound with sulfur dioxide and water. For, instance acetaldehyde will react with sulfur dioxide to make α-hydroxyethane sulfonic acid (HESA) according to the following equation:
<CHM>
As can be seen, the equilibrium can be fully shifted to the feed components by increasing temperature and/or reducing the pressure to drive the SO<NUM> off. Like in this case of acetaldehyde, if the carbonyl is volatile, it is also easily removed into the vapor phase. The acid is hence reversible to readily removable and recyclable materials, unlike mineral acids such as sulfuric, phosphoric, or hydrochloric acid. Methods disclosed herein can use α-hydroxysulfonic acids for pretreatment of feedstocks according to methods described in <CIT>.

<FIG> illustrates a non-limiting example of a method of producing ethanol, distiller's corn oil, and enhanced co-products from a feed comprising wet distiller's grains. In the illustrated embodiment, corn <NUM> is subjected to milling <NUM> to produce meal <NUM>. The meal <NUM> is then treated <NUM> to produce a hydrolysate <NUM> containing fermentable sugars. In a typical treatment step, the meal is mixed with water and the starch is converted into sugars by reaction with enzymes in numerous possible configurations known to those in the art and described in, for example, <NPL>. In a typical ethanol production process, two main enzymes assist in the catalytic breakdown of the starch to glucose. The first is the endoenzyme α-amylase, which acts to break the α-<NUM>,<NUM> glycosidic linkage of the starch to produce oligosaccharides of varying molecular weights called "dextrins. " The breakdown of dextrins is usually performed in the fermenter using a second enzyme, amyloglucosidase, which hydrolyses the dextrins to glucose monomers, which are fermentable sugars. In one embodiment, the treatment process involves cooking/liquefaction with a slurry tank where ground grain is mixed with water and hydrolyzed in the presence of enzymes to produce fermentable sugars such as glucose. The process may involve cooking or, depending on the enzyme, cold-cook, where the hydrolysis is conducted at fermentation temperature, or no-cook, where enzyme is stirred below the gelatinization temperature of the starch. This treatment step may be conducted in batch, continuous, or semi-continuous processes.

Yeast is added to the hydrolysate <NUM> to convert the fermentable sugars to ethanol and carbon dioxide in a first fermentation process <NUM>, thereby producing a first fermentation broth <NUM> containing about <NUM>% ethanol, water, and solids from the grain. The fermentation broth <NUM> is then distilled in a first distillation process <NUM>, producing an ethanol solution <NUM> and whole stillage <NUM>. The whole stillage is then separated <NUM> into thin stillage <NUM> and wet distiller's grains (WDG) <NUM>. Separation <NUM> can be accomplished, for example, by decanting, centrifugation, or any other method that can conveniently separate liquid from solids. A portion of the thin stillage can be routed back to the cooking process as makeup water (not shown), reducing the amount of fresh water required by the cook process. The thin stillage can also be concentrated to produce condensed distiller's solubles (not shown).

The wet distiller's grains <NUM>, which may be mixed with thin stillage, whole stillage, or condensed distiller's grains, is then introduced into an acid hydrolysis pretreatment reaction <NUM> to produce acid hydrolysate <NUM> in which cellulose fibers, hemicellulose, and starch are released from corn fiber in the wet distiller's grains <NUM> and made more accessible to enzymatic hydrolysis. The acid hydrolysis reaction <NUM> may comprise a number of components, including α-hydroxysulfonic acid. The acid hydrolysate <NUM> (pre-treated feedstock) is then subjected to an acid removal process <NUM> where the acid is removed in its component form and is recovered (and optionally scrubbed) either as components or in its recombined from and recycled via recycle stream <NUM> to acid hydrolysis pretreatment reaction <NUM>. The pre-treated feedstock <NUM> with acid removed is then subjected to enzymatic hydrolysis <NUM>, producing a hydrolysate <NUM> containing fermentable sugars. Yeast is added to the hydrolysate <NUM> to convert the fermentable sugars to ethanol and carbon dioxide in a second fermentation process <NUM>, thereby producing a second fermentation broth <NUM> containing about <NUM>% ethanol, water, and solids from the grain. The fermentation broth <NUM> is then distilled in a second distillation process <NUM>, producing an ethanol solution <NUM> and enhanced whole stillage <NUM>. The enhanced whole stillage <NUM> is then separated <NUM> into enhanced thin stillage <NUM> and enhanced wet distiller's grains (E-WDG) <NUM>. The enhanced wet distiller's grains are then dried <NUM> to produce enhanced dried distiller's grains (E-DDG). The enhanced thin stillage <NUM> can be concentrated, such as by evaporation under vacuum, to produce enhanced condensed distiller's solubles (E-syrup), which may be mixed with E-DDG <NUM> to produce enhanced dried distiller's grains with solubles (E-DDGS) (not shown). The separation process <NUM> can also produce separated distiller's corn oil (DCO) <NUM> from the whole stillage. For example, a tricanter centrifuge can be used to separate liquids, solids, and fats to produce enhanced thin stillage <NUM>, enhanced wet distiller's grains <NUM>, and DCO <NUM>.

Additional optional processing steps for removal of sulfur may be performed on the E-thin stillage <NUM> after separation <NUM>. This can be accomplished by membrane separation and/or protein precipitation. A membrane separation process involves passing the E-thin stillage <NUM> through a membrane or series of membranes having pore sizes ranging from <NUM> to <NUM> KDa. This produces a retentate that is enriched in protein and low in sulfur, and a permeate stream that is relatively low in protein and high in sulfur. The protein-rich retentate stream can then be further dried, preferably in a spray dryer to produce E-syrup with low sulfur content. A protein precipitation process for removing sulfur involves adding solvents such as ethanol, THF, or acetone to E-thin stillage <NUM> (or, optionally, to E-syrup) at solvent-to-feed ratios ranging from <NUM> to <NUM>, and preferably of about <NUM>. The protein-rich, low-sulfur precipitate may be separated from the relatively high-sulfur supernate by filtration or centrifugation and then combined with E-WDG <NUM>.

Some embodiments of the methods disclosed herein do not include the initial processing steps of milling <NUM>, treatment <NUM>, fermentation <NUM>, distillation <NUM>, and separation <NUM>. Instead, some embodiments start with acid hydrolysis <NUM> of feedstocks produced previously at the same plant or a different plant. Such feedstock can be wet distiller's grains, whole stillage, or thin stillage produced in a corn ethanol plant, or mixtures thereof. The feedstock for production of ethanol and enhanced co-products may also include wet or dry gluten feed made in a wet milling process. The wet milling production process for gluten feed, which is used as a feedstock in some embodiments disclosed herein, is as follows: First, whole corn kernels are soaked in acid. The resulting steep liquor contains protein, minerals, vitamins, and energy sources. The starch and oil are extracted from the swollen kernel. The remaining fiber or bran is mixed with the steep liquor, making wet gluten feed, which in some embodiments may contain about <NUM> to <NUM>% dry matter. Dry gluten feed is made by drying wet gluten feed, and in some embodiments may contain approximately <NUM>% dry matter. The feedstock for methods disclosed herein may include any combination of wet distiller's grains, whole stillage, thin stillage, and wet or dry gluten. The feedstock may include only one of these substances, or may contain a mixture of <NUM>, <NUM>, <NUM>, or <NUM> of these substances. In some embodiments, one or more of these substances is excluded from the feedstock. In some embodiments, the feedstock mixture has a water content of at least about, at most about, or about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>%, or between any two of these values.

The method of the present invention includes contacting polysaccharide fibers present in a feedstock with α-hydroxysulfonic acid to hydrolyze at least a portion of the polysaccharide fibers, thereby generating fermentable sugars and releasing oil from the polysaccharide fibers. This may be accomplished by mixing the feedstock with an α-hydroxysulfonic acid solution, such as by impregnating the feedstock with α-hydroxysulfonic acid using an impregnator. In some embodiments, during an acid hydrolysis pretreatment step, the concentration of α-hydroxysulfonic acid in the mixture with the feedstock is at least about, at most about, or about, <NUM>, <NUM>, <NUM>, <NUM>, % by weight, preferably <NUM> to <NUM>% by weight of the mixture. The temperature during this acid hydrolysis step may be maintained at least about, at most about, or about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> for a period of time, preferably <NUM> to <NUM>. In some embodiments, said period of time is about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> hours, or between any two of these values. The pH during this acid hydrolysis step may be at least about, at most about, or about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>, or between any two of these values. In some embodiments, at least a portion of the α-hydroxysulfonic acid is removed from the mixture with the feedstock. In some embodiments, at least about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>% of the α-hydroxysulfonic acid is removed from the mixture, or any range derivable therein. Removal may be performed, for example, as described in <CIT>. The removed α-hydroxysulfonic acid may be re-used to perform acid hydrolysis of another portion or another batch of feedstock.

In some embodiments, the pH of the mixture after acid hydrolysis is performed is increased by the addition of a base. The base may be, for example, magnesium hydroxide, ammonia, slake lime, calcium hydroxide, or potassium hydroxide, or any combination thereof. In some embodiments, the pH is increased by adding a <NUM>% NH<NUM>OH solution. In some embodiments, the pH is adjusted to at least about, at most about, or about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>, or between any two of these values, preferably between <NUM> to <NUM>. The target pH may be determined by the optimal conditions for enzymatic hydrolysis of polysaccharides and oligosaccharides in the pretreated feedstock. In some embodiments, the pH is maintained at the target pH during enzymatic hydrolysis via periodic addition of base.

The polysaccharides are further hydrolyzed by enzymes such as cellulases, hemicellulases, and/or pectinases to generate additional fermentable sugars and release further oil from pretreated polysaccharides, as a separate step after acid hydrolysis and before fermentation. In some embodiments, enzymatic hydrolysis is performed for at least a portion of the time during which fermentation is being performed. In some embodiments, enzymatic hydrolysis is performed for a time before fermentation begins and continues for at time after fermentation begins. In some embodiments, the temperature and/or pH may be adjusted at the beginning of fermentation. This may be done, for example, because the optimal conditions for enzymatic hydrolysis may differ from optimal conditions for fermentation. In some embodiments, enzymatic hydrolysis is carried out at a temperature of about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, to <NUM>, or between any two of these values. In some embodiments, the pH is adjusted to <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>, or between any two of these values, for fermentation. In some embodiments, acid hydrolysis produces glucose to a concentration of at least about or about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>/L, or between any two of these values. In some embodiments, enzymatic hydrolysis produces glucose to a concentration of at least about or about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>/L, or between any two of these values.

Fermentation of the fermentable sugars to produce ethanol can be accomplished by a variety of microorganisms. For example, the fermentation may be accomplished by Saccharomyces cerevisiae, Saccharomyces uvarum, Saccharomyces carlsbergensis, Saccharomyces chevalieri, Candida krusei, Candida guilliermondii Candida tropicalis, Candida diddensiae, Candida fabianii, Candida intermedia, Candida maltosa, Candida santamariae, Candida colliculosa, Pichia membranaefaciens, Cryptococcus kuetzingii, Hansenula polymorpha, Kloeckera corticis, Rhodotorula pallida, Rhodotorula rubra, Rhodotorula minuta, Torulopsis norvegica, or Trichosporon cutaneum, or any combination thereof. In some embodiments, the microorganism is capable of fermenting five-carbon sugars such as xylose and arabinose.

In the method of the present invention, the fermentation is carried out at about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>°Cor between any two of these values, wherein the temperature of the mixture is <NUM> to <NUM>. In some embodiments, fermentation is carried out at a pH of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>, or between any two of these values, preferably <NUM> to <NUM>. In some embodiments, fermentation is carried out for a duration of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> hours, or between any two of these values, preferably at least <NUM> hours. In some embodiments, the fermentation consumes at least about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>% of the fermentable sugars present in the mixture after hydrolysis is complete, or between any two of these values. In some embodiments, the fermentation consumes at least about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>% of the glucose present in the mixture after hydrolysis is complete, or between any two of these values. In some embodiments, fermentation produces ethanol in the fermentation broth at a concentration of at least about or about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>/L, or between any two of these values.

Some embodiments include a step of removing oil from the fermentation broth after fermentation but before distillation or from the enhanced whole stillage after distillation. Embodiments can include removing oil at either or both of these times. Oil separation can be accomplished, for example, by centrifugation, by a gravity settler, or by allowing the fermentation broth or whole stillage to sit without agitation. In some embodiments, the weight of the oil removed in this step is at least about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>% of the total weight of the enhanced whole stillage before removal of the oil.

In embodiments in which oil is removed from the fermentation broth before distillation, the removed oil may be flashed to remove any water or ethanol, which can be recovered and combined with the heavy liquid fraction from the settler for subsequent distillation. The enhanced whole stillage produced by the distillation can then be directed to a multi-stage evaporator to produce a syrup, which can then be dried in a spray dryer to produce E-DDG.

The enhanced co-products produced according to methods disclosed herein have enhanced qualities for uses such as animal feed. As used herein, enhanced dried distiller's grains (E-DDG)is a product of a process of treating co-products of a previously performed ethanol production process.

The E-DDG produced by the method of the present invention have a higher percentage of protein than conventional co-products, which can make the enhanced co-products a better source of nutrition than conventional co-products. The E-DDG has a total protein content of at least <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>% on a dry weight basis, or between any two of these values. Crude protein represents the total dietary nitrogen (N) in the diet, which includes not only true protein but also non-protein nitrogen (e.g., urea and ammonia, but not nitrate). The protein content can also be measured as the weight percent of amino acids in the enhanced co-product. In some embodiments, an enhanced co-product has a total amino acid content of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>% on a dry weight basis, or between any two of these values. In some embodiments, an enhanced co-product has a total amino acid content of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>% by weight of the co-product.

The E-DDG produced by the method of the present invention have a lower percentage of fat than conventional co-products. In some embodiments, the enhanced co-products have at most about or about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>% fat on a dry weight basis, or between any two of these values.

Some embodiments of enhanced co-products have a reduced fiber content due to the fiber in the feedstocks being broken down into fermentable sugars in the methods disclosed herein. In some embodiments, the E-DDG has a fiber content that is at most about or is about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>% on a dry weight basis, or is between any two of these values. As used herein, the fiber content refers to NDF fiber content, which includes hemicellulose, cellulose, and lignin.

In some embodiments the E-DDG has a starch content that is at most about or about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>% on a dry weight basis or is between any two of those values.

In some embodiments, E-DDG disclosed herein has a moisture content of at least about, at most about, or about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>%, or between any two of these values.

In some embodiments, the E-DDG has an ash content that is at most about or about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>% on a dry weight basis, or is between any two of these values.

In some embodiments, the enhanced thin stillage produced according to the methods disclosed herein has a moisture content of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>%, or between any two of these values. In some embodiments, the enhanced thin stillage has a crude protein content of at least about, at most about, or about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>% on a dry weight basis, or between any two of these values. The enhanced thin stillage may be dried to produce enhanced syrup having a moisture content of at least about, at most about, or about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>%, or between any two of these values. In some embodiments, the enhanced syrup has a crude protein content of at least about, at most about, or about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>% on a dry weight basis, or between any two of these values.

Embodiments of the enhanced co-products disclosed herein can have any combination of the properties described above. That is, the enhanced co-products can have any combination of two or more of the above-listed values for protein content, amino acid content, fat content, fiber content, starch content, moisture content, and/or ash content.

The disclosed compositions and methods will be described in greater detail by way of specific examples. The following examples are offered for illustrative purposes only, and are not intended to limit the invention in any manner. Those of skill in the art will readily recognize a variety of noncritical parameters which can be changed or modified to yield essentially the same results.

The inventors performed several production runs to process wet cake feedstocks (with or without added thin stillage or syrup) to varying degrees. The general process of these runs included pre-treatment of the feedstock, enzymatic hydrolysis, fermentation, distillation, liquid-solid separation, and drying. These processes were performed in an existing biofuel plant. The features of the biofuel plant and the general procedures for processing biomass are as follows: Biomass (i.e., corn fiber-containing feedstock such as wet cake or a mixture of wet cake and thin stillage) is placed in a biomass hopper and transferred using a transfer screw into an ATM (atmospheric) steam bin, which has a bottom-mounted agitator that feeds the biomass into a plug-screw feeder (PSF). The PSF consists of a biomass inlet, tapered compression zone, screens coupled with a pressate outlet and chip outlet at the discharge into a twin-screw impregnator. The sudden expansion of biomass upon entry into the impregnator allows the chemicals (i.e., HESA cooking solution) to penetrate the biomass homogeneously. The highly compressed biomass is discharged into the impregnator via a blow-back piston (or dampener). In case the plug integrity is compromised, the blow-back dampener acts as a primary barrier preventing SO<NUM> laden vapors from being blown back from the high pressure digester back into the ATM bin. The fully impregnated biomass is elevated above the level of the liquid by counter-rotating twin screws and dropped into a digester. The digester has a conical profile to de-stress the solids as they build level from the bottom. The digest has a nuclear (gamma) level transmitter to monitor level and is mounted with temperature transmitters and controllers. The temperature in the digester is adjusted using steam. The digester has a spike-mounted bottom agitator and fully submerged transfer screw coupled to a cold-blow discharger. The cold-blow discharger has a hollow paddle coupled with a helical string mixer. The cold-blow discharge is coupled to a primary blow tank, which is close-coupled to a blow valve.

During the start-up, a plug is established in the PSF using the biomass. The dry-biomass feed rate is established a priori by calibrating the amount fed into an open digester by feeding a tote or two of the biomass. <NUM># Saturated steam is used to heat the digester until the typical target temperature is achieved. The bottom of the digester up to the cold-blow discharge in this process is filled with condensate, which is moved to the primary blow tank as needed. Once the target temperature in the digester is achieved, HESA and water are introduced, followed by the biomass (by running the transfer screw as needed to maintain a sufficient level in the ATM-bin and running the PSF) in proportions to provide the target liquid-to-biomass ratio (referred to as the L/W ratio (Liquor-to-Wood) or total solids concentration (TS%)). The biomass is filled up to a level to achieve the necessary residence time in the continuous-flow digester and maintained at that level. The bottom agitator in the digester is started ~<NUM> minutes before the target residence time level is achieved. It was not necessary to run the discharge screw to move the cooked pulp into the cold-blow discharger. After the target residence time elapses, the blow-valve is opened to blow the pretreated pulp into the blow tank. Since the blow valve is oversized for the pre-treated feed consistency there is a small window (typically <NUM>-<NUM>% of the valve opening) where a stable level in the digester can be maintained. Hence, the blow-out is essentially pulsed either automatically or manually.

Once blow-out of the pretreated pulp is started, an acid recovery system is brought online to the necessary temperature by heating the blow tank contents that are recirculated using a bottom PC (progressive-cavity) pump as set by the speed of the pump to achieve the target recirculation rate. <NUM># steam is used to heat this recirculation stream indirectly using a spiral exchanger. The recirculation loop pressure is regulated using a back-pressure control valve, which is positioned in the line directed back to the blow tank such that the stream gets to flash the acid once again in the blow tank. Note that the return nozzle (an open pipe in this case) is tangentially oriented. The blow tank level transmitter coupled with the PC pump directs a portion of the blown pulp into a secondary flash tank through a control valve, which is positioned in the recirculation line directed to the flash tank and gives another opportunity to flash the acid components in the secondary flash tank. The PC pump at the bottom of the flash tank, which is coupled with the flash tank level transmitter, is used to discharge the pretreated pulp (lean in acid) into a slop tank until steady state is achieved. As the PC pump is oversized, the flash tank level control was operated ON/OFF. The bottom of the flash tank is directed to slop tank for <NUM> hours and then collected in a day tank as representative pretreated material (lean-in-acid). The day tank is equipped to be able to neutralize the pretreated material to adjust pH as necessary for enzymatic hydrolysis using aqueous ammonia. Both the blow tank and the flash tank have side-mounted agitators at the bottom to avoid settling of solids.

The flashed vapors from the blow tank are directed via a vent manager system to the caustic scrubber coupled with an educator and a circulation system. The recovered acid components are captured as their salt in the scrubber (sodium hydroxyethane sulfonate).

Enzymatic hydrolysis and fermentation were performed in a swing tank having a nominal working volume of <NUM>,<NUM> gal. A beer column and rectification column were used to stage recovery of ethanol from fermentation broth, leaving behind enhanced whole stillage. A Sharples decanter centrifuge is coupled to the bottom of the beer column to perform solid-liquid separation of the enhanced whole stillage to make enhanced thin stillage and enhanced wet cake. A vacuum MVR (mechanical vapor compression) Evaporator was used to make enhanced syrup from the enhanced thin stillage.

Biomass feedstock (wet cake and thin stillage) were acquired from a dry mill corn ethanol plant. Wet cake was stored under refrigeration, and thin stillage was stored at <NUM> to <NUM>.

The specific conditions for individual processing runs are described in the further Examples below. Except as indicated otherwise, the procedures for the subsequent Examples were carried out on the equipment and following the procedures described above in this Example <NUM>.

Run <NUM>: Wet cake was pretreated according to the process described in Example <NUM>. The wet cake was impregnated with HESA solution and pretreatment was carried out in the digester at a temperature of <NUM> ± <NUM> and a pressure of <NUM> - <NUM> psig, with a retention time of <NUM> - <NUM>. The concentration of HESA in the digester was maintained at ~<NUM>%. The total solids percentage in the wet cake feed was between <NUM> and <NUM>%, and the total solids percentages in the pretreated feed in the blow tank and flash tank were between <NUM> and <NUM>%.

Run <NUM>: The same wet cake feed as used in Run <NUM> was pretreated under the conditions set forth above for Run <NUM>. A portion of the pretreated wet cake was collected and used for enzymatic hydrolysis and fermentation. Two <NUM> reactors were filled with <NUM> of the pretreated slurry. The temperature was increased to <NUM>, and the pH was adjusted to <NUM> using <NUM> - <NUM> of <NUM>% ammonia. Lactrol was then added, along with <NUM>% (<NUM>) of CTec3 HS enzyme, to each <NUM> reactor. After <NUM> hours, some liquefaction was observable. The temperature was maintained at <NUM> ± <NUM> for <NUM> hours (with the exception of <NUM> hours during which the temperature control malfunctioned, and the temperature ranged from <NUM> to <NUM> (which did not affect enzyme stability)), and the pH was maintained at <NUM>. Fermentation was then performed by reducing the temperature set point to <NUM> ± <NUM>, adjusting the pH set point to <NUM> ± <NUM>, and inoculating the hydrolysate with yeast. Fermentation continued for <NUM> hours, during which the temperature and pH were maintained at the set points. The fermentation broth was then heated to <NUM> for <NUM> minutes to kill the yeast.

<FIG> shows that during hydrolysis of the pretreated wet cake in Run <NUM>, the glucose concentration increased from about <NUM>/L to about <NUM>/L. <FIG> shows that during fermentation, the Ethanol concentration increased to about <NUM>/L. <FIG> shows that the glucose, xylose, arabinose, and mannose present in the hydrolysate were substantially entirely consumed during fermentation.

Run <NUM>: The same wet cake feed as used in Run <NUM> (Example <NUM>) was pretreated under the conditions set forth for Run <NUM> above, except that the total concentration of HESA in the pretreated feed was between <NUM> and <NUM> wt% in the blow tank and between <NUM> and <NUM> wt% in the flash tank and the total solids percentages in the pretreated feed in the blow tank and flash tank were between <NUM> and <NUM>%.

Run <NUM>: Pretreated wet cake slurry from Runs <NUM>, <NUM>, and <NUM> (<NUM> is outside scope of the claims) (~<NUM> to <NUM> gal from each, for a total of ~<NUM> gal) was pooled into a <NUM> gallon swing tank. The swing tank was set to maintain the temperature at <NUM> ± <NUM> and the pH was set to be maintained at <NUM> ± <NUM> by addition of <NUM>% NH<NUM>OH as needed throughout the enzymatic hydrolysis step. Approximately <NUM> gal of <NUM>% NH<NUM>OH was required to initially increase the pH to <NUM>. Lactrol was added, followed by <NUM>% (<NUM>) of an enzyme cocktail including cellulase and hemicellulase activity, added gradually over the course of <NUM> minutes. Enzymatic hydrolysis continued under the same conditions for <NUM> hours.

A Saccharomyces cerevisiae yeast culture for fermentation was prepared by combining <NUM> of sterilized YPD growth medium (<NUM>/L yeast extract, <NUM>/L peptone, <NUM>/L glucose, and <NUM>/L xylose), <NUM>/L Lactrol, and <NUM> stabilized liquid yeast and incubating with an aeration rate of <NUM> vvm and <NUM> rpm agitation in a reactor for approximately <NUM> hours.

The wet cake hydrolysate in the swing tank was adjusted to pH <NUM> using NH<NUM>OH and cooled to <NUM>, and the <NUM> of yeast culture from the propagator was added to the swing tank. Fermentation continued with the temperature maintained at <NUM> ± <NUM> and pH maintained at <NUM> for <NUM> hours. The fermentation broth (beer) was transferred to a distillation column and heated to <NUM> for <NUM> minutes for yeast kill. After distillation, <NUM> lbs of ~<NUM>% ethanol was collected, and <NUM> gal of enhanced whole stillage was collected. The enhanced whole stillage was run through a Sharples centrifuge, which did not achieve good liquid-solid separation. The centrate was left overnight, after which DCO had separated as a layer on top of the enhanced whole stillage ("E-whole stillage"). The DCO was skimmed off, and the remaining enhanced whole stillage was run through a Flottweg decanter centrifuge run at <NUM> rpm (<NUM>% torque). The enhanced whole stillage was <NUM>-<NUM>% TS when fed into the centrifuge, and the exiting enhanced wet cake (enhanced wet distiller's grains, or "E-wet cake") was measured at <NUM>% TS. <NUM> Gallon of this enhanced wet cake was air-dried to produce enhanced dried distiller's grains (E-DDG). The enhanced thin stillage from the Flottweg was sent to the MVR evaporated and concentrated 4X to make enhanced syrup ("E-syrup").

<FIG> shows the total amino acid content of the indicated samples from Run <NUM> on a dry weight basis. <FIG> shows the crude protein content of the indicated samples from Run <NUM> (including the wet cake feed from Run <NUM>) on a dry weight basis. The crude protein content of a sample represents the total dietary nitrogen (N) in the diet, which includes not only true protein but also non-protein nitrogen (e.g., urea and ammonia, but not nitrate). <FIG> shows the total fat content on a dry weight basis of the indicated samples from Run <NUM>, as measured by acid hydrolysis. Table <NUM> below sets forth properties of various samples of feed and co-products from Run <NUM>.

Run <NUM>: Wet cake (<NUM>% TS) from a dry mill corn ethanol plant was impregnated with HESA solution as it was fed into the digester. Thin stillage from the same corn ethanol plant was added to the digester as well. The mixed feed in the digester had <NUM>% TS and <NUM> wt% HESA. Pretreatment was carried out in the digester at a temperature of <NUM> ± <NUM> and a pressure of <NUM> - <NUM> psig, with a retention time of <NUM>. Total solids percentages of the pretreated feed in the blow tank and flash tank were ~<NUM>%. A portion of the pretreated wet cake was collected and used for enzymatic hydrolysis and fermentation. Two <NUM> reactors were filled with <NUM> of cooled, pretreated slurry. The temperature was increased to <NUM>, and the pH was adjusted to <NUM> using <NUM>% NH<NUM>OH. Lactrol was then added, along with <NUM>% (<NUM>) of CTec3 HS enzyme, to each <NUM> reactor. The temperature was maintained at <NUM> ± <NUM> for <NUM> hours, and the pH was maintained at <NUM>. Fermentation was then performed by reducing the temperature set point to <NUM> ± <NUM>, adjusting the pH set point to <NUM> ± <NUM>, and inoculating the hydrolysate with yeast. Fermentation continued for <NUM> hours, during which the temperature and pH were maintained at the set points. The fermentation broth was then heated to <NUM> for <NUM> minutes to kill the yeast.

Run <NUM>: Ethanol was produced from a feed of wet cake mixed with condensed distiller's solubles (syrup) following the same protocol as Run <NUM>. Two E-DDG samples were prepared from the enhanced wet cake post-centrifugation by oven drying: one "long-dry" sample and one "normal-dry" sample. <FIG> shows the crude protein content on a dry weight basis of the indicated samples from Run <NUM>. <FIG> shows the total amino acid content on a dry weight basis of the indicated samples from Run <NUM>. <FIG> shows the NDF content (hemicellulose, cellulose, and lignin) on a dry weight basis of the indicated samples from Run <NUM>. Table <NUM> below sets forth properties of various samples from Run <NUM>.

DCO was collected from whole stillage and analyzed to determine the fatty acid profile. The results are as follows, given in terms of weight percent: Total fatty acid: <NUM>; C14:<NUM> Myristic Acid: <NUM>; C16:<NUM> Palmitic Acid: <NUM>; C16:<NUM> Palmitoleic Acid: <NUM>; C17:<NUM> Heptadecanoic Acid: <NUM>; C18:<NUM> Stearic Acid: <NUM>; C18:1w7 Vaccenic Acid: <NUM>; C18:1w9 Oleic Acid: <NUM>; C18:2w6 Linoleic Acid: <NUM>; C18:3w3 Linolenic Acid: <NUM>; C20:<NUM> Arachidic Acid: <NUM>; C20:1w9 Eicosenoic Acid: <NUM>; C22:<NUM> Behenic Acid: <NUM>; C24:<NUM> Nervonic Acid: n/a; C24:<NUM> Lignoceric Acid: <NUM>; Other Fatty Acids: <NUM>.

The amino acid profile of the protein from the E-DDG normal-dry sample was determined to be as follows, given in terms of weight percent of the indicated amino acid in the E-DDG on a dry weight basis: cysteine: <NUM>; methionine: <NUM>; lysine: <NUM>; alanine: <NUM>; aspartic acid: <NUM>; glutamic acid: <NUM>; glycine: <NUM>; isoleucine: <NUM>; leucine: <NUM>; proline: <NUM>; threonine: <NUM>; valine: <NUM>; arginine: <NUM>; histidine: <NUM>; hydroxylysine: <NUM>; hydroxyproline: <NUM>; lanthionine: <NUM>; ornithine: <NUM>; phenylalanine: <NUM>; serine: <NUM>; taurine: <NUM>; tyrosine: <NUM>; tryptophan: <NUM>; total amino acids: <NUM>.

The above specification and examples provide a complete description of the implementation and structure of illustrative embodiments. Although certain embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the scope of this invention. As such, the various illustrative embodiments of the compositions, methods, and systems are not intended to be limited to the particular forms disclosed. Rather, they include all modifications and alternatives falling within the scope of the claims, and embodiments other than the one shown may include some or all of the features of the depicted embodiment. For example, elements may be omitted or combined as a unitary step or structure, and/or may be substituted. Further, where appropriate, aspects of any of the examples described above may be combined with aspects of any of the other examples described to form further examples having comparable or different properties and/or functions, and addressing the same or different problems. Similarly, it will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments.

Claim 1:
A method of processing fiber-containing co-products of an alcohol production process, the method comprising:
(a) contacting polysaccharide fibers present in a mixture comprising one or more co-products of an alcohol production process with an α-hydroxysulfonic acid to hydrolyze at least a portion of the polysaccharide fibers, thereby generating fermentable sugars and releasing oil from the polysaccharide fibers, wherein the one or more co-products of an alcohol production process comprise one or more of the following:
(i) wet distiller's grains;
(ii) thin stillage;
(iii) whole stillage; and
(iv) gluten feed;
wherein the concentration of α-hydroxysulfonic acid is <NUM> to <NUM>% by weight of the mixture, and the temperature of the mixture is <NUM> to <NUM>;
(b) increasing the pH of the mixture by adding a base to the mixture;
(c) contacting polysaccharide fibers in the mixture with enzymes to hydrolyze the polysaccharide fibers, thereby generating additional fermentable sugars and releasing further oil from the polysaccharide fibers, wherein the temperature of the mixture is <NUM> to <NUM>;
(d) incubating the mixture with yeast under anaerobic conditions to produce alcohol by fermenting fermentable sugars produced in steps (a) and (c), wherein the temperature of the mixture is <NUM> to <NUM>;
(e) distilling the mixture to remove alcohol from the mixture, thereby producing an alcohol-containing distillate and enhanced whole stillage;
(f) removing released oil from the fermented mixture produced in step (d) and/or from the enhanced whole stillage produced in step (e);
(g) separating the enhanced whole stillage to produce enhanced wet distiller's grains and enhanced thin stillage; and
(h) drying the enhanced wet distiller's grains to remove moisture, thereby producing enhanced dried distiller's grains (E-DDG) having a total protein content of at least <NUM>% on a dry weight basis and a total fat content of no more than <NUM>% on a dry weight basis.