CA1190497A - Process for making fermentable sugars and high protein products - Google Patents
Process for making fermentable sugars and high protein productsInfo
- Publication number
- CA1190497A CA1190497A CA000410574A CA410574A CA1190497A CA 1190497 A CA1190497 A CA 1190497A CA 000410574 A CA000410574 A CA 000410574A CA 410574 A CA410574 A CA 410574A CA 1190497 A CA1190497 A CA 1190497A
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- Prior art keywords
- protein
- water
- starch
- sugar solution
- grain
- Prior art date
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E50/00—Technologies for the production of fuel of non-fossil origin
- Y02E50/10—Biofuels, e.g. bio-diesel
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Abstract
Abstract Disclosed is a dry or wet milling process for making fermentable sugars and high-protein products from starch bearing material, characterized by saccharification of the starch followed by recovery of fiber all other non-protein materials and of destarched protein as separate products, leaving a sugar solution that is essentially free of insoluble materials. The sugars are fermented to ethanol and carbon dioxide by the action of added yeast. After fermentation, ?east is recovered for use in fermenting additional quantities of sugars supplied either for batch or continuous processing. The alcohol is then removed leaving a dilute solution of unfermentable soluble materials, and this liquid, in whole or in part, is recycled to preceding steps in the process.
Description
~ 292-190 Background of the Invention Materials which contain starch and protein, o:Eten accompanied by other so:Luble and insoluble substcmces, are comlllercia:lly processed to separate these materials into var:i.ous :Lractions, W]liC}l Illay also be :Eurther processed, if de-sired. The weight of each fraction, its composition and the total percentage of material recovered depends both upon the composition of the raw material and on the exact processing steps to which it is subjected.
In commercial processing, it is desire~l -to maximize the tota:L value o:E all the fractions recovered, as long ~s the increased value is greater than any increased costs ol processing. In general, the value of a Eraction is greater as its purity is increased, alld the total value is greater with in-creased recovery of the more valuable :Eractions.
The art to which this invention relates has been very active through the years, as evidenced by the following patents:
U.S. Patent No. 2,6~8,826 refers to a process wherein a starchy mate-rial is transformed into a magma containing solubles and unconverted starch which is centrifuged to provide an overflow containing the solubles and an underflow containing the starch. A fresh water wash is introduced into the centrifuge zone.
In U.S. Patent No. 3,236,7~0 there is disclosed a process for produc-i.ng alcohol which entails degerminating corn to form a germ fraction and a degerminated starchy fraction; extracting the germ fraction for its germ oil;
adding some of the extract to the degerminated fraction; cooking the combined fractions; neutralizing the cooked material, cooling the cooked mash to saccha-rifying temperature; saccharifying -the cooled mash cooling to fermenting tempera-ture; fermenting and recovering the a.lcohol.
U.S. Patent No. 3,236,7~0 discloses a process wherein, instead of mill-U.S.S.N. 170,033 - 1 ing the fiber after gert,l removal and separation of the "grit starch", the fiber and its associatccl starcll and protein are put through an alcohol-making proce-dure. In this process, yeast is not recycled ancl starch is lost to fermcllta-tion with the mol ancl gluten comillg from the primclry separator.
U.S. Patents 2~230,31c and 2,063,223 describe the re-use of yeast to increase alcohol yields but only in reference to molasses, which is clarified before fermentation.
Distilleries typically produce grain alcohol by converting the starch in grain to sugar, fermenting the sugar to alcohol, recovering the aLcohoL by dist:illation, and recovering the remaining materials by removing the water.
T]lis residual material is solcl as an:imal feed and has tnUCIl lcss value thall the alcohol. The total value of production is increased by maximizing the recovery of starch as alcohol rather than allowing it to go to -the feed fraction which has lower value. Furthermore, the value of the fec-~d is improved throug~h effec-tive increase of its protein content when the starch is kept out of it.
Accordingly, it is an object of the present invention to prov:ide a prc~cess for producing alcohol from corn, starchy roots, legumes and grain which yields a higher percentage of alcohol than prior ar-t processes.
Another object of the present :invention is to provide a process for producing by-products with a much higher economic value than prior art processes.
A further object of the present invention is to provicle a process for producing alcohol which uses less water and energy than prior known processes.
Still another object of the present invention is to produce a new and valuable product, destarched corn gluten.
Summary The present invention is concerned with processes for maximizing the cumulative total value of the products made from starch-bearing mater:ials that 4~7 contain insoluble proteinaceous material, with or without containing other insoluble and/or soluble substances, by recovering the starch in higl- yields in the forlll o:E soluble carbohydr.l-tes or as :Eermenta-t:i.oll prod~cts and by recovering an unusually high percentage o:E -the insoluble protein present in a highly puri-ficd form.
Suitable raw materials include starchy rootsJ legumcs, and grains, but the preferred materials are cereal grains or fractions of cereal g~ains whicll have been prepared by wet or dry separation methods.
One of the most advantageous uses o:E the processes is i.n the mall~l:Eac-ture o:E volatile products o:E carbohydrate :Ecrmcntation, espec:ially o:E ethylalcchol (also known as ethanol, alcollol, grain spiri-ts, etc).
This novel process for producing alcohol from corn, compared wi-th regular distillery practice:
-produces higher alcohol yields -produces by-products witll mucll higller value -uses less fresh water and thus consumes less energy for evaporation and drying, and compared with previously used combinations of wet-milling and alcohol pro-cesses:
-uses less equip3llent -recovers a substantially grea-ter amount oE starcll cLS alCOI10 -loses less protein to Corn Gluten Feed -produces a new and valuable product-Des-tarched Corn Gluten.
I`he corn is steeped Eor a length of time in warm water that has been acidified with S02, at about 50 in -tanks through which the water flows succes-sively, as is standard practice in the corn wet-milling industry. The process differs from the standard procedure (where starch is sought as tlle prime pro-duct) in that steeping is carried out for a shorter period oE time, only long enough to toughen the hull and germ sufficiently to make clean germ removal pos-sible in the next step. Because oE the shorter period of steeping7 there is less solubilization of starch and protein, and therefore, a lower yield of steepwater solids than otherwise. The carbohydrates and proteins that would otherwise be solubilized are now available for recovery as alcohol and gluten respectively. Light steepwater exiting the system is kept preferably high in solids to reduce the amount of water to evaporate in the Eollowing evaporator.
This is accomplished by reducing the amount of fresh water supplied the whole system.
Brief Description of thc Drawings In the accompallyillg diagramatic drawings forming part hereof similar elements have been given the same rcEerellce numeral~ in whicll drawings:
Figure 1 is a flow cliagram showing the prior art processes.
Figure 2 is a flow sheet illustrating a preferred embodiment of the present invention.
Figure 3 is a flow sheet illustrating the prior art dry milling pro-cess; and Figure ~ is a flow sheet showing a preferred dry milling embodimellt according to the instant inventioll.
Detailed Description In the traditional clistillery operation, dry grain is ground by roller or hammer mills, cooked with water, treated with malt, acid or enzyme to convert starch into sugars, followed by fermentation with yeast, distillation oE the alcohol and recovery oE the unfermented materials by evaporation and drying of the water remaining after alcohol removal. Part of the sugars are consumed in growing yeast both in the fermenting step and in a propagation step carried on outside of the process. This diversion of sugar causes a corresponding reduc-tion in yield of alcohol. Large amounts of fresh water are used in the cooking and fermentation steps, with correspondingly large amounts to be evaporated and dried in recovering the by-product.
The cost of alcohol produced by this method is inherently high because of low alcohol yields, low value of the single by-productg and lligh steam con-sumption for evaporating and drying the large amounts of water.
Because of the high costs entailed, the traditional distillery process has been largely supplanted, in the U.S. at least, wherever Grain Neutral Spirits for beverage purposes, or industrial alcohol Eor solvent or chemical 9~
intermediate purposes is required. Inclustrial grades have been mostly made by the hydration of ethylene, and the Grain Neutral Spirits are llOW made almost en-tirely in combincltioll witll processes originally clesigned to recover othervaluable products Erom grain.
The most important oE these is the corn wet-milling process which has been developed over a period of more than one hundred years as a means of ob--taining in as pure a state as possible, the starch that is present in the kernels of corn. (See Figure 1).
Illis process is reasonably standard, but may be practiced with var-ia-tions in details accorcling to local circ~nstances. In acldition to starch, it recovers other compollents of the kerllel, such as protein, oil, Eiber, and ash in the form of more or less refined by-products. The general process may also be used in -the recovery of starch and by-products from other grains such as wheat,sorxhum (milo), barley, etc.
In thc wet-milling process as usually practiced with corn, ~see Figure 1), shelled grain is cleaned in stage 10, to remove gross impurities, tramp metal, small particles and dust. In steeping stage 11, the cleaned kernels are steeped in water containing soluble ingredients of corn and a ~uan-tity of sulfur dioxide, for a period of up to ~0 hours or more at a temperature of approximately 50 C (122 F). The sulfur dioxide water permeates into the kernel; it toughens the outer hull, toughens the corn germ, which contains most of the oil~ and softens protein material that holds the germ and hull to the inner part of the kernel. The inner part oE the kernel consists of a matrix of protein enclosing granules of starch, and the steeping process also serves to soften this protein network, to facilitate recovery of the maximum amount of starch.
During the steeping process, tle water used for soaking is moved counter-currently to the corn, and is removed in the form of "l;ght steepwater"
12 which contains protein, ash, carbohydrate, lactic acid, ctc. at a dry sub-stance concelltratioll of some 3 to 10~. The ligllt steepwater is subsequently concentrated by an evapora-tor 13 for sale as is, or to be combined in mixer 1 with fiber and other materials and dried 15 Eor use as an ingredient (corn gluten feed) in animal feed formulas.
After steeping, the kernels are drained oE excess water and are coarsely milled at L6 to free the -toughened germ from the rest of the kernel.
Because the germ contains a large amount of oil, it is lighter than the other componellts of the kernel so it Call be separated by gravimetric methods from the remaining magma by settling in germ separator 17 or by hydroclones, as prac-ticed by those skilled in the art. Two stages of milling and separation are usually used; the germ is co~mtercurrently washed free oE adhering materials, dewatered as indicated at 18, and dried at 19. Valuable corn oil is removed from it either by expelling or solvent extrac-tion, ~not shown).
The remaining magma 20 consists of Eiber, s-tarch, and protein (gluten);
some of the starch and gluten are freely suspended in the water but a large amount also remains attached to the cellulosic fiber of the hull. The loose particles are screened out at 21 and advanced in the process~ while the fiber is treated to free the adhering protein and starch. This is accomplished by a fiber mill 22, followed by a series of washing steps and dewatering 23 suspend-ing the fiber in water, screening it, resuspending it, etc., with the water mov-ing countercurrently to the fiber. The milled and washed -fiber is -then mixed in mixer l~ and other materials, and dried at 15 to produce corn gluten feed.
The protein and starch which have been washed -from the fiber join that which originally passed through the screen 21 and advanced in the process. The nex-t step is to separate the protein in as pure a form as possible, from this suspen-sion of starch and protein.
The starch and gluten are separated using centrifugal machines 24 which produce a protein stream that contains from about 67 to 70% or even a li-ttle higller dry substance proteill. T}lis material is concentrated, filtered at 25 and dried in dryer 26 and sold as "corn gluten meal". It contains, in addi-tion to protein and some 15 to 20% of starch a concentration of oils and fatty materials including "~anthophyll oil" which is valued as a coloring material for use in chicken feed Eormulations. After the protein has been recovered, there remains a slurry of starch, with some protein, very fine fiber, and other mate-rials in solution. The next step is to remove the protein fiber and solubles whic}l is accomplished by countercurrent washing Wit]l fres]l water in a series of stages of hydroclones 28, ranging in number rom abo~lt 8 to lS ~ependillg upon the specific conditions. Tlle impure starch slurry 27 enters the first stage of the hydroclones and it leaves the last stage in a highly purified condition at a higll concentration. This washed starch is then dried or used as the raw mate-rial for treated, converted, or blended starches, for dextrins, or sweeteners such as glucose, dex-trose, high fructose syrup, etc.
Fresh water enters the last hydroclone stage and leaves the first carrying with it some starch as well as solubles, protein and fine fiber that have been washed from the product. The weight of dry material washed back at this point is often as much as 20 to 25% of the dry substance amount entering the washing station. It is concentrated in a centrifugal machine 29 and re-turned to the main stream 30 eitl-er before the fiber washing s-tation or before the protein separator 24.
The outstanding features of this process are the recovery of high yields of starch and by-products in purified conditions that add to the value of each of them. ~urthermore, this is accomplished with -the use of small amounts of fresh water - in the order of 11 to 12 gallons or less per bushel (5O lbs) of ~9~497 corn ground, and no water leaves the process except as part of steepwater, starch slurry or dewatered by-produc-ts, and this is renoved by evaporation or drying, or leaves as part of -the product or by-product.
ilowever, in order to achieve these results, there are certain penal-ties that must be yaid: To free the m~i 1m amount of starch during the steeping operati.on, some protein and carbohydrates are solubilized and become part of steepwater rather than -the more valuable Gluten ~leal or starch. To recover the r~-ir-1m starch that is bound to the fiber, considera.ble power :is used i.n milling, and undesirable amounts of very fine fiber, wh:ich are very difficult to remove, are formed. The recycle of the starch wash overflow resu:lts in accumlllatiolls o:E
fine fiber, broken starch granules, and protein, which lllake gluten separation difficult .
It has been found that many of these problems can be overcome by add-ing a sub-process for alcohol production, whereby starch is recovered as alcohol from various of the streams. If the fibers are processed for alcohol, a great deal of power for milling may be saved, and less starch is carr:ied to lower value Corn Gluten Feed; if part or all of the starch washing recycle mainstream is processed for alcohol recycle of extra fine fiber and broken starch granules is interrupted and gluten separation is improved. ~The presence of variable alcohol capabilities has an added advantage of providing means to smooth out seasonal variations in demand for starch products). When more alcohol is re-quired than can be supplied from the starch i.n fiber and starch washing recycle, other streams, such as the flow 27 from the protein separator 2~ to the sta.rch washing station 28 can be tapped into as indicated by -the valves 40,~ 2 of Figure 1.
Alcohol is produced from the starch in these streams in the same man-ner as if it were whole grain being processed as described above by cooking at _ 9 _ 4~37 31, saccharifying 32, fermenting 33, distillation 34 to remove the alcohol and recovery at 35 of the unfermented materials. This latter step is different from whole grain processing in that the solubles content of the solution is very much lower, so it may be recycled :in toto. I`he insoluble fraction 36 is also less since it has been reduced by the prior removal of the germ and part of the pro-tein. After dewatering the insolubles are mixed with concentrated steepwater from evaporator 13 and dried to produce animal feed material. However, this feed is higher in protein content than the Corn Gluten Feed of regular corn wet-milling due to (l) removal of starch which increases the percentage of protein, and (2) the protein in the starch washillg recycle (and separator underflow when used) is recovered along with the fibcr. Since the protein content of this feed material is higller than the normal product, it commancls a higher price in the market. Alternativelyl a standard protein content can be achieved by adding lower-cost materials, thus increasing the quantity produced.
Nevertheless, the quantity of more valuable Corn Gluten Meal is re-duced by virtue of diversion of protein to less valuable feed.
Compared with the Prior Art distillery process, alcohol prod~lced in this manner is very much less costly, basically due to the higher value of the up-graded by-products and to the use of much less water for which energy must be expended in evaporation and drying. The method also benefits from the economies of scale induced by combining with major starch producing facilities, especially when the quantity of alcohol is small in relation to the amount of corn pro-cessed.
However, when it is desired to produce large amounts of alcohol with relation to the starch produced, or when it is desired to make no starch at all, certain of the process steps become superfluous, and certain of the process advantages become diminished. The novel process described below and diagram-matically shown in l~igure 2 has been designed -to not only overcome these diEfi-culties but also to produce a new and valuable product.
As showll in Figure 2, the first step of -the process is to soak the corn for a length of time in warm watcr that has been acidified with sulfur dioxide at about 50C in tanks through which the water flows successively, as is standard practice in the corn wet-milllng industry. 'rhe process difers from the standard procedure ~wllere starch is sought as the prime product) in that steeping is carried out for a shor-ter period of time, only long enougll to toughen tlle hull and germ suEEiciently to make clean germ removal i~ossible ;al the next step~ Because of the shorter period of steeping, there is less solu-bilization of starch and protein, and thereEore, a lower yield of steepwater solids than would be normal. The carbohydrates and proteins -that would other-wise be solubilized are now available Eor recovery as alcohol and gluten respect-ively. Light steepwater exiting the system is kept preferably high in solids to reduce ~he amount of water needed to evaporate in the following evaportor.
Tllis is accomplished by balancing the amount of Eresh water supplied the whole system.
The next step is that of germ removal wllich is carried out according to any standard corn wet-milling method which recovers germ with little adhered starch and protein, in a form suitable for expelling or extracting its valuable corn oil.
The magma remaining after steeping and germ removal is composed of water, solubles and insoluble material, with water comprising approximately 75 to 80% by weight of the total. The solubles are minerals, proteins~ carbo-hydrates and other materials, while the insolubles consist primarily of starch, protein, fiber and fatty mc~terials. Since the presence of high concentrations of solubles impedes the ability to recycle waters la-ter in -the process, it is important to reduce them as much as possible at this point, before the starch is cooked alld solubili~ed.
I`llis is accomplislled by dewater:ing the magma to as lo~ a moisture con-tent as possible, and Usillg the water to wash germ and especially to supply water to the steeps whence it exits as l:ight steepwater. This is effective since solubles follow the water, and if the magma is clewatered from 80~ moisture to 50% moisture, only one-Eourtll oE the solubles will go forward with lhe de-watered material. Further reduction can be obtained by resuspending the mate-rial and dewatering it again. I-t is optional whetller the mclterial is milled further either before or after dewaterillg.
The ne~t steps of the process are designed to convert all or essenti-ally all of the starch to fermentable sugars, remove all or essentially all the carbohydrates and protein from the fiber, and to remove the fiber from the system; then to remove the protein from the system in a highly purified state.
This is accomplished by the successive steps oE (1~ liquefying and saccharifying the starch, (2) screening out -the fiber and washing it free of adhering mate-rials by countercurrent washing with wateZ low in solubles, (3) removing the re-maining insoluble material (primarily protein) by centrifugal or other means, followed by dewatering (with or without washing) and drying.
The remaining solution consists primarily of sugars which may be treated further to produce commercial useful sweeteners or they may be used as a substrate for fermen-tation to other materials of which ethanol is the most inter-esting for fuel use. The following descriptions enlarge upon the steps outlined above:
(1) The liquefaction and saccharification of the starch may be car-ried out by any of the methods normally used in the industry, such as the "acid", "acid-enzyme" or '~enzyme" processes. In the acid conversion method, the starch slurry :is cooked at an elevated temperature in the presence of strong acid, usually hydroclllor:ic. ~he s-tarch is converted into shorter-chain carbohydrates havillg a composition rallgillg from a high l)ercelltage o~ dextrin ancl starch-like compounds to a very high percentage of dextrose ~D-Glucose), depellding upon -the conditions of treatment.
In the acid-enzyme method, liquefaction and some saccharification are done with acid, followed by adjustmellt of conditions and saccharification with glucoamylase enzyme.
In the enzyllle metllod, lkluefacti.on is carried out with alpha-alDylase and saccharification with glucoamylase or bo-th may be done with mixecl enzymes SUC}I as those in barley malt or certain flmgal amylases.
In commercial processing, it is desire~l -to maximize the tota:L value o:E all the fractions recovered, as long ~s the increased value is greater than any increased costs ol processing. In general, the value of a Eraction is greater as its purity is increased, alld the total value is greater with in-creased recovery of the more valuable :Eractions.
The art to which this invention relates has been very active through the years, as evidenced by the following patents:
U.S. Patent No. 2,6~8,826 refers to a process wherein a starchy mate-rial is transformed into a magma containing solubles and unconverted starch which is centrifuged to provide an overflow containing the solubles and an underflow containing the starch. A fresh water wash is introduced into the centrifuge zone.
In U.S. Patent No. 3,236,7~0 there is disclosed a process for produc-i.ng alcohol which entails degerminating corn to form a germ fraction and a degerminated starchy fraction; extracting the germ fraction for its germ oil;
adding some of the extract to the degerminated fraction; cooking the combined fractions; neutralizing the cooked material, cooling the cooked mash to saccha-rifying temperature; saccharifying -the cooled mash cooling to fermenting tempera-ture; fermenting and recovering the a.lcohol.
U.S. Patent No. 3,236,7~0 discloses a process wherein, instead of mill-U.S.S.N. 170,033 - 1 ing the fiber after gert,l removal and separation of the "grit starch", the fiber and its associatccl starcll and protein are put through an alcohol-making proce-dure. In this process, yeast is not recycled ancl starch is lost to fermcllta-tion with the mol ancl gluten comillg from the primclry separator.
U.S. Patents 2~230,31c and 2,063,223 describe the re-use of yeast to increase alcohol yields but only in reference to molasses, which is clarified before fermentation.
Distilleries typically produce grain alcohol by converting the starch in grain to sugar, fermenting the sugar to alcohol, recovering the aLcohoL by dist:illation, and recovering the remaining materials by removing the water.
T]lis residual material is solcl as an:imal feed and has tnUCIl lcss value thall the alcohol. The total value of production is increased by maximizing the recovery of starch as alcohol rather than allowing it to go to -the feed fraction which has lower value. Furthermore, the value of the fec-~d is improved throug~h effec-tive increase of its protein content when the starch is kept out of it.
Accordingly, it is an object of the present invention to prov:ide a prc~cess for producing alcohol from corn, starchy roots, legumes and grain which yields a higher percentage of alcohol than prior ar-t processes.
Another object of the present :invention is to provide a process for producing by-products with a much higher economic value than prior art processes.
A further object of the present invention is to provicle a process for producing alcohol which uses less water and energy than prior known processes.
Still another object of the present invention is to produce a new and valuable product, destarched corn gluten.
Summary The present invention is concerned with processes for maximizing the cumulative total value of the products made from starch-bearing mater:ials that 4~7 contain insoluble proteinaceous material, with or without containing other insoluble and/or soluble substances, by recovering the starch in higl- yields in the forlll o:E soluble carbohydr.l-tes or as :Eermenta-t:i.oll prod~cts and by recovering an unusually high percentage o:E -the insoluble protein present in a highly puri-ficd form.
Suitable raw materials include starchy rootsJ legumcs, and grains, but the preferred materials are cereal grains or fractions of cereal g~ains whicll have been prepared by wet or dry separation methods.
One of the most advantageous uses o:E the processes is i.n the mall~l:Eac-ture o:E volatile products o:E carbohydrate :Ecrmcntation, espec:ially o:E ethylalcchol (also known as ethanol, alcollol, grain spiri-ts, etc).
This novel process for producing alcohol from corn, compared wi-th regular distillery practice:
-produces higher alcohol yields -produces by-products witll mucll higller value -uses less fresh water and thus consumes less energy for evaporation and drying, and compared with previously used combinations of wet-milling and alcohol pro-cesses:
-uses less equip3llent -recovers a substantially grea-ter amount oE starcll cLS alCOI10 -loses less protein to Corn Gluten Feed -produces a new and valuable product-Des-tarched Corn Gluten.
I`he corn is steeped Eor a length of time in warm water that has been acidified with S02, at about 50 in -tanks through which the water flows succes-sively, as is standard practice in the corn wet-milling industry. The process differs from the standard procedure (where starch is sought as tlle prime pro-duct) in that steeping is carried out for a shorter period oE time, only long enough to toughen the hull and germ sufficiently to make clean germ removal pos-sible in the next step. Because oE the shorter period of steeping7 there is less solubilization of starch and protein, and therefore, a lower yield of steepwater solids than otherwise. The carbohydrates and proteins that would otherwise be solubilized are now available for recovery as alcohol and gluten respectively. Light steepwater exiting the system is kept preferably high in solids to reduce the amount of water to evaporate in the Eollowing evaporator.
This is accomplished by reducing the amount of fresh water supplied the whole system.
Brief Description of thc Drawings In the accompallyillg diagramatic drawings forming part hereof similar elements have been given the same rcEerellce numeral~ in whicll drawings:
Figure 1 is a flow cliagram showing the prior art processes.
Figure 2 is a flow sheet illustrating a preferred embodiment of the present invention.
Figure 3 is a flow sheet illustrating the prior art dry milling pro-cess; and Figure ~ is a flow sheet showing a preferred dry milling embodimellt according to the instant inventioll.
Detailed Description In the traditional clistillery operation, dry grain is ground by roller or hammer mills, cooked with water, treated with malt, acid or enzyme to convert starch into sugars, followed by fermentation with yeast, distillation oE the alcohol and recovery oE the unfermented materials by evaporation and drying of the water remaining after alcohol removal. Part of the sugars are consumed in growing yeast both in the fermenting step and in a propagation step carried on outside of the process. This diversion of sugar causes a corresponding reduc-tion in yield of alcohol. Large amounts of fresh water are used in the cooking and fermentation steps, with correspondingly large amounts to be evaporated and dried in recovering the by-product.
The cost of alcohol produced by this method is inherently high because of low alcohol yields, low value of the single by-productg and lligh steam con-sumption for evaporating and drying the large amounts of water.
Because of the high costs entailed, the traditional distillery process has been largely supplanted, in the U.S. at least, wherever Grain Neutral Spirits for beverage purposes, or industrial alcohol Eor solvent or chemical 9~
intermediate purposes is required. Inclustrial grades have been mostly made by the hydration of ethylene, and the Grain Neutral Spirits are llOW made almost en-tirely in combincltioll witll processes originally clesigned to recover othervaluable products Erom grain.
The most important oE these is the corn wet-milling process which has been developed over a period of more than one hundred years as a means of ob--taining in as pure a state as possible, the starch that is present in the kernels of corn. (See Figure 1).
Illis process is reasonably standard, but may be practiced with var-ia-tions in details accorcling to local circ~nstances. In acldition to starch, it recovers other compollents of the kerllel, such as protein, oil, Eiber, and ash in the form of more or less refined by-products. The general process may also be used in -the recovery of starch and by-products from other grains such as wheat,sorxhum (milo), barley, etc.
In thc wet-milling process as usually practiced with corn, ~see Figure 1), shelled grain is cleaned in stage 10, to remove gross impurities, tramp metal, small particles and dust. In steeping stage 11, the cleaned kernels are steeped in water containing soluble ingredients of corn and a ~uan-tity of sulfur dioxide, for a period of up to ~0 hours or more at a temperature of approximately 50 C (122 F). The sulfur dioxide water permeates into the kernel; it toughens the outer hull, toughens the corn germ, which contains most of the oil~ and softens protein material that holds the germ and hull to the inner part of the kernel. The inner part oE the kernel consists of a matrix of protein enclosing granules of starch, and the steeping process also serves to soften this protein network, to facilitate recovery of the maximum amount of starch.
During the steeping process, tle water used for soaking is moved counter-currently to the corn, and is removed in the form of "l;ght steepwater"
12 which contains protein, ash, carbohydrate, lactic acid, ctc. at a dry sub-stance concelltratioll of some 3 to 10~. The ligllt steepwater is subsequently concentrated by an evapora-tor 13 for sale as is, or to be combined in mixer 1 with fiber and other materials and dried 15 Eor use as an ingredient (corn gluten feed) in animal feed formulas.
After steeping, the kernels are drained oE excess water and are coarsely milled at L6 to free the -toughened germ from the rest of the kernel.
Because the germ contains a large amount of oil, it is lighter than the other componellts of the kernel so it Call be separated by gravimetric methods from the remaining magma by settling in germ separator 17 or by hydroclones, as prac-ticed by those skilled in the art. Two stages of milling and separation are usually used; the germ is co~mtercurrently washed free oE adhering materials, dewatered as indicated at 18, and dried at 19. Valuable corn oil is removed from it either by expelling or solvent extrac-tion, ~not shown).
The remaining magma 20 consists of Eiber, s-tarch, and protein (gluten);
some of the starch and gluten are freely suspended in the water but a large amount also remains attached to the cellulosic fiber of the hull. The loose particles are screened out at 21 and advanced in the process~ while the fiber is treated to free the adhering protein and starch. This is accomplished by a fiber mill 22, followed by a series of washing steps and dewatering 23 suspend-ing the fiber in water, screening it, resuspending it, etc., with the water mov-ing countercurrently to the fiber. The milled and washed -fiber is -then mixed in mixer l~ and other materials, and dried at 15 to produce corn gluten feed.
The protein and starch which have been washed -from the fiber join that which originally passed through the screen 21 and advanced in the process. The nex-t step is to separate the protein in as pure a form as possible, from this suspen-sion of starch and protein.
The starch and gluten are separated using centrifugal machines 24 which produce a protein stream that contains from about 67 to 70% or even a li-ttle higller dry substance proteill. T}lis material is concentrated, filtered at 25 and dried in dryer 26 and sold as "corn gluten meal". It contains, in addi-tion to protein and some 15 to 20% of starch a concentration of oils and fatty materials including "~anthophyll oil" which is valued as a coloring material for use in chicken feed Eormulations. After the protein has been recovered, there remains a slurry of starch, with some protein, very fine fiber, and other mate-rials in solution. The next step is to remove the protein fiber and solubles whic}l is accomplished by countercurrent washing Wit]l fres]l water in a series of stages of hydroclones 28, ranging in number rom abo~lt 8 to lS ~ependillg upon the specific conditions. Tlle impure starch slurry 27 enters the first stage of the hydroclones and it leaves the last stage in a highly purified condition at a higll concentration. This washed starch is then dried or used as the raw mate-rial for treated, converted, or blended starches, for dextrins, or sweeteners such as glucose, dex-trose, high fructose syrup, etc.
Fresh water enters the last hydroclone stage and leaves the first carrying with it some starch as well as solubles, protein and fine fiber that have been washed from the product. The weight of dry material washed back at this point is often as much as 20 to 25% of the dry substance amount entering the washing station. It is concentrated in a centrifugal machine 29 and re-turned to the main stream 30 eitl-er before the fiber washing s-tation or before the protein separator 24.
The outstanding features of this process are the recovery of high yields of starch and by-products in purified conditions that add to the value of each of them. ~urthermore, this is accomplished with -the use of small amounts of fresh water - in the order of 11 to 12 gallons or less per bushel (5O lbs) of ~9~497 corn ground, and no water leaves the process except as part of steepwater, starch slurry or dewatered by-produc-ts, and this is renoved by evaporation or drying, or leaves as part of -the product or by-product.
ilowever, in order to achieve these results, there are certain penal-ties that must be yaid: To free the m~i 1m amount of starch during the steeping operati.on, some protein and carbohydrates are solubilized and become part of steepwater rather than -the more valuable Gluten ~leal or starch. To recover the r~-ir-1m starch that is bound to the fiber, considera.ble power :is used i.n milling, and undesirable amounts of very fine fiber, wh:ich are very difficult to remove, are formed. The recycle of the starch wash overflow resu:lts in accumlllatiolls o:E
fine fiber, broken starch granules, and protein, which lllake gluten separation difficult .
It has been found that many of these problems can be overcome by add-ing a sub-process for alcohol production, whereby starch is recovered as alcohol from various of the streams. If the fibers are processed for alcohol, a great deal of power for milling may be saved, and less starch is carr:ied to lower value Corn Gluten Feed; if part or all of the starch washing recycle mainstream is processed for alcohol recycle of extra fine fiber and broken starch granules is interrupted and gluten separation is improved. ~The presence of variable alcohol capabilities has an added advantage of providing means to smooth out seasonal variations in demand for starch products). When more alcohol is re-quired than can be supplied from the starch i.n fiber and starch washing recycle, other streams, such as the flow 27 from the protein separator 2~ to the sta.rch washing station 28 can be tapped into as indicated by -the valves 40,~ 2 of Figure 1.
Alcohol is produced from the starch in these streams in the same man-ner as if it were whole grain being processed as described above by cooking at _ 9 _ 4~37 31, saccharifying 32, fermenting 33, distillation 34 to remove the alcohol and recovery at 35 of the unfermented materials. This latter step is different from whole grain processing in that the solubles content of the solution is very much lower, so it may be recycled :in toto. I`he insoluble fraction 36 is also less since it has been reduced by the prior removal of the germ and part of the pro-tein. After dewatering the insolubles are mixed with concentrated steepwater from evaporator 13 and dried to produce animal feed material. However, this feed is higher in protein content than the Corn Gluten Feed of regular corn wet-milling due to (l) removal of starch which increases the percentage of protein, and (2) the protein in the starch washillg recycle (and separator underflow when used) is recovered along with the fibcr. Since the protein content of this feed material is higller than the normal product, it commancls a higher price in the market. Alternativelyl a standard protein content can be achieved by adding lower-cost materials, thus increasing the quantity produced.
Nevertheless, the quantity of more valuable Corn Gluten Meal is re-duced by virtue of diversion of protein to less valuable feed.
Compared with the Prior Art distillery process, alcohol prod~lced in this manner is very much less costly, basically due to the higher value of the up-graded by-products and to the use of much less water for which energy must be expended in evaporation and drying. The method also benefits from the economies of scale induced by combining with major starch producing facilities, especially when the quantity of alcohol is small in relation to the amount of corn pro-cessed.
However, when it is desired to produce large amounts of alcohol with relation to the starch produced, or when it is desired to make no starch at all, certain of the process steps become superfluous, and certain of the process advantages become diminished. The novel process described below and diagram-matically shown in l~igure 2 has been designed -to not only overcome these diEfi-culties but also to produce a new and valuable product.
As showll in Figure 2, the first step of -the process is to soak the corn for a length of time in warm watcr that has been acidified with sulfur dioxide at about 50C in tanks through which the water flows successively, as is standard practice in the corn wet-milllng industry. 'rhe process difers from the standard procedure ~wllere starch is sought as the prime product) in that steeping is carried out for a shor-ter period of time, only long enougll to toughen tlle hull and germ suEEiciently to make clean germ removal i~ossible ;al the next step~ Because of the shorter period of steeping, there is less solu-bilization of starch and protein, and thereEore, a lower yield of steepwater solids than would be normal. The carbohydrates and proteins -that would other-wise be solubilized are now available Eor recovery as alcohol and gluten respect-ively. Light steepwater exiting the system is kept preferably high in solids to reduce ~he amount of water needed to evaporate in the following evaportor.
Tllis is accomplished by balancing the amount of Eresh water supplied the whole system.
The next step is that of germ removal wllich is carried out according to any standard corn wet-milling method which recovers germ with little adhered starch and protein, in a form suitable for expelling or extracting its valuable corn oil.
The magma remaining after steeping and germ removal is composed of water, solubles and insoluble material, with water comprising approximately 75 to 80% by weight of the total. The solubles are minerals, proteins~ carbo-hydrates and other materials, while the insolubles consist primarily of starch, protein, fiber and fatty mc~terials. Since the presence of high concentrations of solubles impedes the ability to recycle waters la-ter in -the process, it is important to reduce them as much as possible at this point, before the starch is cooked alld solubili~ed.
I`llis is accomplislled by dewater:ing the magma to as lo~ a moisture con-tent as possible, and Usillg the water to wash germ and especially to supply water to the steeps whence it exits as l:ight steepwater. This is effective since solubles follow the water, and if the magma is clewatered from 80~ moisture to 50% moisture, only one-Eourtll oE the solubles will go forward with lhe de-watered material. Further reduction can be obtained by resuspending the mate-rial and dewatering it again. I-t is optional whetller the mclterial is milled further either before or after dewaterillg.
The ne~t steps of the process are designed to convert all or essenti-ally all of the starch to fermentable sugars, remove all or essentially all the carbohydrates and protein from the fiber, and to remove the fiber from the system; then to remove the protein from the system in a highly purified state.
This is accomplished by the successive steps oE (1~ liquefying and saccharifying the starch, (2) screening out -the fiber and washing it free of adhering mate-rials by countercurrent washing with wateZ low in solubles, (3) removing the re-maining insoluble material (primarily protein) by centrifugal or other means, followed by dewatering (with or without washing) and drying.
The remaining solution consists primarily of sugars which may be treated further to produce commercial useful sweeteners or they may be used as a substrate for fermen-tation to other materials of which ethanol is the most inter-esting for fuel use. The following descriptions enlarge upon the steps outlined above:
(1) The liquefaction and saccharification of the starch may be car-ried out by any of the methods normally used in the industry, such as the "acid", "acid-enzyme" or '~enzyme" processes. In the acid conversion method, the starch slurry :is cooked at an elevated temperature in the presence of strong acid, usually hydroclllor:ic. ~he s-tarch is converted into shorter-chain carbohydrates havillg a composition rallgillg from a high l)ercelltage o~ dextrin ancl starch-like compounds to a very high percentage of dextrose ~D-Glucose), depellding upon -the conditions of treatment.
In the acid-enzyme method, liquefaction and some saccharification are done with acid, followed by adjustmellt of conditions and saccharification with glucoamylase enzyme.
In the enzyllle metllod, lkluefacti.on is carried out with alpha-alDylase and saccharification with glucoamylase or bo-th may be done with mixecl enzymes SUC}I as those in barley malt or certain flmgal amylases.
(2) After the saccharification step, the carbohydrates may be easily washed from the fiber, carrying other solubles and finely divided insolubles, including the protein, with them. This is carried out by counter-current wash-ing with fresh or other low-soluble water in a bent-screen or other fiber wash-ing arrangement which is normally used in the starch industry, except that fewer stages are required to reduce the amount exiting with the fiber to a very low level.
After washing, the fiber is dewatered and may be dried separately or in combination with concentrated steepwater to produce Corn Gluten Feed, an item of commerce that is used as an ingredient in animal feeds. Other materials such as corn screenings, refinery residue, etc. may also be added ~o this feed as is normal practice in the industry. Water removed in the dewatering opera-tion is passed to the fiber washing station and, by moving counter-currently, helps re-turn the soluble carbohydrates to the main stream.
After washing, the fiber is dewatered and may be dried separately or in combination with concentrated steepwater to produce Corn Gluten Feed, an item of commerce that is used as an ingredient in animal feeds. Other materials such as corn screenings, refinery residue, etc. may also be added ~o this feed as is normal practice in the industry. Water removed in the dewatering opera-tion is passed to the fiber washing station and, by moving counter-currently, helps re-turn the soluble carbohydrates to the main stream.
(3) The liquid remaining after removal of the washed fiber is a solu-tion consisting of fermentable sugars and small amounts of other solubles such as inorganic salts and protein. Suspended in this are insoluble substances such as protei.n (primar:ily) with small amounts o.E finely divided fiber, and oils and fats.
These insoluble substances are removed by centrifugal methods which are common in the art, single stage or multiple, or by filtration alone or in combinatioll with centri:Eugatioil, with or without counter-current washing. They are dried to about 10% moisture. Comi)ared with the gl.uten produced by normcll corn wet-milling, this product is very llighly pur;.:Eied and contains up to ~0%
or more pure protein on a dry substance bas:is, as compared w;.th llorlllcll 67 to 75%. It contains a concentration o the xanthophyll oi.l from corn, which is the coloring material that is used to bring yellow color to poultry skin and eggs via their feeds. This oil may be recovered by solvent extraction with hexane or other appropriate non-toxic solvent. Because of its extremely hi.gh protein content, the gluten has exceptional value as animal or human food and as a starting point for further processing.
~ 4) After removal of the insolubles, the solution consists essenti-ally of sugars, which can be processed in different ways. The sugars can be con-centrated by evaporation to form syrup with or without refining; cast as solid sugar or crystallized as dextrose, or they can be reacted chemically or especi-ally fermented to various compounds, of which ethanol is of major importance.
To produce alcohol, the sugar solution is cooled to a suitable tempera-ture for yeast fermentation in either batch or continuous processing. After fermentation is complete, yeast - both that which was introduced and that which grew during the course of the fermentation-is essenti.ally the only insoluble material present. I-t can then be removed centrifugally, as is often done in molasses fermentations, but not previously practiced with grain, and reused in a 1~ -ermentation vat. This recycle allows use of greater amounts of yeast result-ing in faster .Eermentation. This recycling also obviates the need for growing more yeast from -the sugars, thereby cnsur:ing a higher yiel.d o:E ~lcohol to the extent thclt the yeast multiplles due to partially aerobic conditions in the fermentation, there is excess yeast to be removed in the form of dead and damaged cells as well as good ones. Since these cells consist of high amounts of protein, they are useful as an additive to feed materi.als.
~ l example of the practice of the invention is given in the flow sheet of Figure 2. A charge consis-ting of 1183 pounds ~1000 pounds of dry sub-stances) of clean corn is placed in a series o tanks 4~1 through WhiCIl warm S02water is flowed at 50C for steey:ing or lcach.ing the corn Eor 10 to 30 hours.
The yield of steepwater solids was 65 pounds and the light steepwater exiting through line 46 was ~Eound to total 813 poullds including 748 lbs. of water, 682 pounds of water were evaporated in multi-e:Efect evaporator 48. The concentrated steepwater from evaporator 48 was flowed to feed mixer 49 via line 50.
The charge was flowed from tanks 44 via line 52 to germ mill and separator system 54 which includes a coarse attrition mill and hydrocyclones as is commonly practiced. The germ in the overflow were sent along line 56 for washing in washer 58 using recycled water introduced through line 60. Water is also recycled from dewatering station 62 via line 64 and from germ dewatering station 66 via line 68. The germ is dewatered i.n the presses of station 66 and sent on to germ dryer 70 by way of line 72. After drying, the recovered germ was found to be 79 pounds including 2% moisture and approximately 39 pounds of oil.
The underflow from separator system 54 containing fibers, starch, pro-tein, soluble and insoluble materials is flowed to station 62 via line 55 where the water content thereof is dewatered from about 80 to about 50%. Optionally, ~9~
the material is milled before dewatering. The expelled water is recycled to wasll the germ .~nd for steeping via line 64.
In this exalllple~ the en~yme metllod of liqueEaction and sacchariEica-tion was used. The dewatered material is flowed through the cooking and liquefying section 74 where the pll is adjusted, alpha-amylase such as J`ermamil 60 of Novo Industri A/S is added, with the addition of 313 lbs of water intro-duced by line 75 which recycles water from the bottom of the beer stil].
Some 360 pounds oE direct steam are injected during the cooking pro-cess, and 300 pounds are flashecl ofE after cooking, during cooling to sacchari-fication temperature of about 60C, the pl-l :is adjusted to 4.0 to 4.5 ancl enough glucoamylase is added to reach a dextrose equivalent of about 75 in about 6 hours~ Using an en7yme such as Novo 150 produced by Novo Industri A/S the quantity is approximately 1 to 1.5 liters per metric ton oE dry substance starch.
After saccharification of the starch, the stream passes through line 82 to screening section 84 for removal of coarse insoluble materials, almost entirely fiber. This is accomplished in a few stages of bent screens such as normally used in the industry.
The fiber is removed by a fine screen, and is then successively resus-pended in counter-currently flowing water from tank 83 and rescreened to remove a ~xi ~m of the soluble material, in section 84. 1033 pounds of fresh water are introduced here via line 85 and is part of the co~mter-current washing stream. The solubles removed from the fiber pass through line 81 to the first screen in 84 and through it to the next station. Washed fiber passes through line 88 to a dewatering press 90 of usual type, where the moisture content is reduced mechanically from about 95% to 63%. Water removed here (1401 lbs.) re-turns to the washing station through line 92 while the dewatered fiber passes through line 94 to a pre-dryer 96 where the moisture content is reduced to approximately 20 -to 40%. Predried iber then passes through line 98 to feed mixer 49 where it is mixed with concentrated s~eepwater as well as other mate-rials which may optionally be added here S~lCh as corn cleanings, refinery res:idue, etc. Tlle mixture thcn passes througll line 108 to Feed Dryer 110 where it is clried in normal fashion to approximately 10% moisture content with usual milling, screening and recycle.
The sugar solution, wllicll still contains finely divided, suspended particles of insoluble protein, is sent on by line 112 to one or more centri-fuges and/or filters 114 for removal of the pro-teln (gluten). Pr.ior to and dur-i.ng the process of protein recovery some 2~22 pounds of water recycled from thebottom of the beer stlll 80 are added to the stream as a means of washlJIg the proteln and to dllu-te the sugars to the concentratlon required ln the fermenta-tlon step. The 65 pounds of recovered proteln ls then dewatered ln a fllter 116 from approxlmately 88% molsture to about 60% moisture. T}le water removed at thls step whlch contains sugars, ls flowed in llne 118 and passes through llne 118 to joln the sugar solutlon comlng from fllters 114 through llne 120. The dewatered gluten is then flowed through pipe 121 and dried in a usual manner to about 10% moisture ln dryer 122.
The sugar solut:ion is then cooled -to fermentatlon temperature of about 30C and recycled yeast ls added through llne 124. The amount of water here ls adjusted to control the concentratlon of alcohol ln the fermented mash as re-quired by the amount and type of yeast employed, fermentatlon time available, and other pertlnent varlables. In the example an alcohol concentratlon of 8.1%
by welght (about 10% by volume) was obtained.
I~ermentatlon ls carrled out ln statlon 126, which may be any sort of batch, semi-contlnuous or contlnuous yrocess. During fermentation, some 398 pounds of carbon dioxide gas are evolved ancl this may be recovered or not accord-lng to the economlcs of the case.
9~
After fermentation has been concluded, the mash passes through a normal type of noææle centrifuge 129 for recovery of the yeast. ~lost of this :is returlled tllrougll line l24 to the fermenter station, but some is bled of~ and incorporated into tile Corn Gluten l:eed. The fermellted mash, W]liC]I iS now essentially free of :insolubles passes -througll line 130 to the f:irst distillation stage 80 (often called "beer still") where the alcohol is stripped from the mashthrougll line 132. In the example, 384 pounds of crude alcohol were recovered for further processing, at a concelltration of about 74% by weight. This concen-tration may be varied according to usual practice, and the alcohol Cclll be further processed as re(luired to produce spirits for beverage ind-lstrial, fuel, or other uses.
The water discharged from the bottom of the beer still 80 columll con-tains very low solubles and is recycled through line 13~ for re-use at earlier points in the process as descr:ibed above.
Table I below provides a comparison between yields obtained with the present process and the prior art distillery process. In that table, it is noteworthy to remark that the present process uses only 682 pounds of fresh water against 3212 pounds by the prior art process. It also used 360 pounds o steam against 547 pounds by the prior art process. The amount of alcohol pro-duced by the present process is 3~4 pounds against 369 pounds yielded by the other distillery process. Advantageously, the subject process produces corn oil and gluten not produced by the other.
~L~g~ 7 Lbs/1000 lbs Clean Corn D.S.(Dry Sollds) ProductionDi~tilleryPresent New Proce~s Alcohol (Absolute Ba~ls3 369 3~4 Feed Product 30% Pro~ein 362 21~/o Protein - 232 Corn Oil - 34 Gluten (80% Proteln~ - 72 Fresh Water Consumed by Process 3413 1033 Steam for Cook~ng 547 360 Water to b~ evaporated in Dryers ~88 362 ~n evaporater~ 3212 682 The above example has been given as only one presently preferred embodiment of the invention. Many variations w~thin its spirit will occur to those skilled in the art ancl these variations also form part of this invention.
For example, the advantage~ of this process may be combined with the ~tarch alcohol process earlier descrlbed in Figure I.
It may also advantageously be combined with the classical distillery proces~ where gra~n i~ dry-milled. The proces~
may be shortened to remove both germ and fiber to~ether.
The raw material u~ed may be any carbohydrate bear~n~
materials sueh as graln sorghum (milo~, wheat, barley, rice, ~oybean, alfalfa, tapioca, potato, yams and banana~.
J.9 .. ~ _ ~ ~9~ ~ 7 ! The sugar~ may be fermented to materials other than alcohol, such as N-butanol and aeetone, glycerol, lactlc acid, butylene glycol, citrlc, gluconic an~l itaconic aclds and Iderivat:ized compounds thereof by reaction~ known per ~e.
l'he sugar~ m~y be removed without fermentatîon a~ a concent:rated ~yrup, a~ CA~t or cry~tallized sugars.
The proce~s may be practiced without recycle of the yea~, where its production is glven preference over yields of alcohol, The variou~ non-carbohydra~e ~treams may be co~binl!d in dlf~erent ways with or without addi~ion o other materials to form different by-products without depar~in~ from the 'spir~t of the invention.
The proce~s may be practiced without full recycle of :l5 the liquid remaining after the alcohol ha3 been 3tripped o~f, without affec~in~ the ~cope of the lnvention, but thi~ will require more fresh water and energy to evaporate the liquid.
An~ther emhodiment of the invention is its use in improving the traditional distillery process for producing alcohol where a dry-milled gxain is used. In this process, the ground grain i5 suspended in water, and the starch con-verted to sugars by quccessive steps of cooking and ~reatment with acids and~or enzymes. ~he temperature and acidity are adjusted and the resulting mash is placed in a fermenter tank and 'starter' yeast is supplied from an ou~side source.
In the fermenter tank, the yeast consumes ~he fermentable ~g~
~ug2rs and both propagates itself and produces alcohol. When the sugar ha~ been consumed, the alcohol is removed by distillation, and the non-fermentable materials are recovered for use as an animal ~eed product, usually as a single by-product called "Distillers Drled (;rains and Solubles".
This process may be improvecl in several ways by using the invention:
tl) Yeast may be recycled and this results in using shorter fermenta~ion time and smaller fermenters.
~2) ~ore alcohol is formed from the carbohydrate, since les~ yeast is grown.
( 3) A new ~y-product which contains high purity protein i8 produced.
Figure 3 outlines the traditional process, and Figure 4, the application of the novel proce~sO In the la~ter case, th~ coar~e insolubles (mostly cellulosic materials), and the fine in~olubles (mostly protein and fatty materials)are removed before fermentation. ~f~er fermentation, the yeast which is the only remaining insoluble material i~ recovered centrifugally and returned to the ~rmentera. Animal feed i8 produced by drying the coarse insoluble together with the solubles; no decanter i~ r~qui~ed after ~he stills, ~ince the insolubles have already been removed in earlier ~tep~0
These insoluble substances are removed by centrifugal methods which are common in the art, single stage or multiple, or by filtration alone or in combinatioll with centri:Eugatioil, with or without counter-current washing. They are dried to about 10% moisture. Comi)ared with the gl.uten produced by normcll corn wet-milling, this product is very llighly pur;.:Eied and contains up to ~0%
or more pure protein on a dry substance bas:is, as compared w;.th llorlllcll 67 to 75%. It contains a concentration o the xanthophyll oi.l from corn, which is the coloring material that is used to bring yellow color to poultry skin and eggs via their feeds. This oil may be recovered by solvent extraction with hexane or other appropriate non-toxic solvent. Because of its extremely hi.gh protein content, the gluten has exceptional value as animal or human food and as a starting point for further processing.
~ 4) After removal of the insolubles, the solution consists essenti-ally of sugars, which can be processed in different ways. The sugars can be con-centrated by evaporation to form syrup with or without refining; cast as solid sugar or crystallized as dextrose, or they can be reacted chemically or especi-ally fermented to various compounds, of which ethanol is of major importance.
To produce alcohol, the sugar solution is cooled to a suitable tempera-ture for yeast fermentation in either batch or continuous processing. After fermentation is complete, yeast - both that which was introduced and that which grew during the course of the fermentation-is essenti.ally the only insoluble material present. I-t can then be removed centrifugally, as is often done in molasses fermentations, but not previously practiced with grain, and reused in a 1~ -ermentation vat. This recycle allows use of greater amounts of yeast result-ing in faster .Eermentation. This recycling also obviates the need for growing more yeast from -the sugars, thereby cnsur:ing a higher yiel.d o:E ~lcohol to the extent thclt the yeast multiplles due to partially aerobic conditions in the fermentation, there is excess yeast to be removed in the form of dead and damaged cells as well as good ones. Since these cells consist of high amounts of protein, they are useful as an additive to feed materi.als.
~ l example of the practice of the invention is given in the flow sheet of Figure 2. A charge consis-ting of 1183 pounds ~1000 pounds of dry sub-stances) of clean corn is placed in a series o tanks 4~1 through WhiCIl warm S02water is flowed at 50C for steey:ing or lcach.ing the corn Eor 10 to 30 hours.
The yield of steepwater solids was 65 pounds and the light steepwater exiting through line 46 was ~Eound to total 813 poullds including 748 lbs. of water, 682 pounds of water were evaporated in multi-e:Efect evaporator 48. The concentrated steepwater from evaporator 48 was flowed to feed mixer 49 via line 50.
The charge was flowed from tanks 44 via line 52 to germ mill and separator system 54 which includes a coarse attrition mill and hydrocyclones as is commonly practiced. The germ in the overflow were sent along line 56 for washing in washer 58 using recycled water introduced through line 60. Water is also recycled from dewatering station 62 via line 64 and from germ dewatering station 66 via line 68. The germ is dewatered i.n the presses of station 66 and sent on to germ dryer 70 by way of line 72. After drying, the recovered germ was found to be 79 pounds including 2% moisture and approximately 39 pounds of oil.
The underflow from separator system 54 containing fibers, starch, pro-tein, soluble and insoluble materials is flowed to station 62 via line 55 where the water content thereof is dewatered from about 80 to about 50%. Optionally, ~9~
the material is milled before dewatering. The expelled water is recycled to wasll the germ .~nd for steeping via line 64.
In this exalllple~ the en~yme metllod of liqueEaction and sacchariEica-tion was used. The dewatered material is flowed through the cooking and liquefying section 74 where the pll is adjusted, alpha-amylase such as J`ermamil 60 of Novo Industri A/S is added, with the addition of 313 lbs of water intro-duced by line 75 which recycles water from the bottom of the beer stil].
Some 360 pounds oE direct steam are injected during the cooking pro-cess, and 300 pounds are flashecl ofE after cooking, during cooling to sacchari-fication temperature of about 60C, the pl-l :is adjusted to 4.0 to 4.5 ancl enough glucoamylase is added to reach a dextrose equivalent of about 75 in about 6 hours~ Using an en7yme such as Novo 150 produced by Novo Industri A/S the quantity is approximately 1 to 1.5 liters per metric ton oE dry substance starch.
After saccharification of the starch, the stream passes through line 82 to screening section 84 for removal of coarse insoluble materials, almost entirely fiber. This is accomplished in a few stages of bent screens such as normally used in the industry.
The fiber is removed by a fine screen, and is then successively resus-pended in counter-currently flowing water from tank 83 and rescreened to remove a ~xi ~m of the soluble material, in section 84. 1033 pounds of fresh water are introduced here via line 85 and is part of the co~mter-current washing stream. The solubles removed from the fiber pass through line 81 to the first screen in 84 and through it to the next station. Washed fiber passes through line 88 to a dewatering press 90 of usual type, where the moisture content is reduced mechanically from about 95% to 63%. Water removed here (1401 lbs.) re-turns to the washing station through line 92 while the dewatered fiber passes through line 94 to a pre-dryer 96 where the moisture content is reduced to approximately 20 -to 40%. Predried iber then passes through line 98 to feed mixer 49 where it is mixed with concentrated s~eepwater as well as other mate-rials which may optionally be added here S~lCh as corn cleanings, refinery res:idue, etc. Tlle mixture thcn passes througll line 108 to Feed Dryer 110 where it is clried in normal fashion to approximately 10% moisture content with usual milling, screening and recycle.
The sugar solution, wllicll still contains finely divided, suspended particles of insoluble protein, is sent on by line 112 to one or more centri-fuges and/or filters 114 for removal of the pro-teln (gluten). Pr.ior to and dur-i.ng the process of protein recovery some 2~22 pounds of water recycled from thebottom of the beer stlll 80 are added to the stream as a means of washlJIg the proteln and to dllu-te the sugars to the concentratlon required ln the fermenta-tlon step. The 65 pounds of recovered proteln ls then dewatered ln a fllter 116 from approxlmately 88% molsture to about 60% moisture. T}le water removed at thls step whlch contains sugars, ls flowed in llne 118 and passes through llne 118 to joln the sugar solutlon comlng from fllters 114 through llne 120. The dewatered gluten is then flowed through pipe 121 and dried in a usual manner to about 10% moisture ln dryer 122.
The sugar solut:ion is then cooled -to fermentatlon temperature of about 30C and recycled yeast ls added through llne 124. The amount of water here ls adjusted to control the concentratlon of alcohol ln the fermented mash as re-quired by the amount and type of yeast employed, fermentatlon time available, and other pertlnent varlables. In the example an alcohol concentratlon of 8.1%
by welght (about 10% by volume) was obtained.
I~ermentatlon ls carrled out ln statlon 126, which may be any sort of batch, semi-contlnuous or contlnuous yrocess. During fermentation, some 398 pounds of carbon dioxide gas are evolved ancl this may be recovered or not accord-lng to the economlcs of the case.
9~
After fermentation has been concluded, the mash passes through a normal type of noææle centrifuge 129 for recovery of the yeast. ~lost of this :is returlled tllrougll line l24 to the fermenter station, but some is bled of~ and incorporated into tile Corn Gluten l:eed. The fermellted mash, W]liC]I iS now essentially free of :insolubles passes -througll line 130 to the f:irst distillation stage 80 (often called "beer still") where the alcohol is stripped from the mashthrougll line 132. In the example, 384 pounds of crude alcohol were recovered for further processing, at a concelltration of about 74% by weight. This concen-tration may be varied according to usual practice, and the alcohol Cclll be further processed as re(luired to produce spirits for beverage ind-lstrial, fuel, or other uses.
The water discharged from the bottom of the beer still 80 columll con-tains very low solubles and is recycled through line 13~ for re-use at earlier points in the process as descr:ibed above.
Table I below provides a comparison between yields obtained with the present process and the prior art distillery process. In that table, it is noteworthy to remark that the present process uses only 682 pounds of fresh water against 3212 pounds by the prior art process. It also used 360 pounds o steam against 547 pounds by the prior art process. The amount of alcohol pro-duced by the present process is 3~4 pounds against 369 pounds yielded by the other distillery process. Advantageously, the subject process produces corn oil and gluten not produced by the other.
~L~g~ 7 Lbs/1000 lbs Clean Corn D.S.(Dry Sollds) ProductionDi~tilleryPresent New Proce~s Alcohol (Absolute Ba~ls3 369 3~4 Feed Product 30% Pro~ein 362 21~/o Protein - 232 Corn Oil - 34 Gluten (80% Proteln~ - 72 Fresh Water Consumed by Process 3413 1033 Steam for Cook~ng 547 360 Water to b~ evaporated in Dryers ~88 362 ~n evaporater~ 3212 682 The above example has been given as only one presently preferred embodiment of the invention. Many variations w~thin its spirit will occur to those skilled in the art ancl these variations also form part of this invention.
For example, the advantage~ of this process may be combined with the ~tarch alcohol process earlier descrlbed in Figure I.
It may also advantageously be combined with the classical distillery proces~ where gra~n i~ dry-milled. The proces~
may be shortened to remove both germ and fiber to~ether.
The raw material u~ed may be any carbohydrate bear~n~
materials sueh as graln sorghum (milo~, wheat, barley, rice, ~oybean, alfalfa, tapioca, potato, yams and banana~.
J.9 .. ~ _ ~ ~9~ ~ 7 ! The sugar~ may be fermented to materials other than alcohol, such as N-butanol and aeetone, glycerol, lactlc acid, butylene glycol, citrlc, gluconic an~l itaconic aclds and Iderivat:ized compounds thereof by reaction~ known per ~e.
l'he sugar~ m~y be removed without fermentatîon a~ a concent:rated ~yrup, a~ CA~t or cry~tallized sugars.
The proce~s may be practiced without recycle of the yea~, where its production is glven preference over yields of alcohol, The variou~ non-carbohydra~e ~treams may be co~binl!d in dlf~erent ways with or without addi~ion o other materials to form different by-products without depar~in~ from the 'spir~t of the invention.
The proce~s may be practiced without full recycle of :l5 the liquid remaining after the alcohol ha3 been 3tripped o~f, without affec~in~ the ~cope of the lnvention, but thi~ will require more fresh water and energy to evaporate the liquid.
An~ther emhodiment of the invention is its use in improving the traditional distillery process for producing alcohol where a dry-milled gxain is used. In this process, the ground grain i5 suspended in water, and the starch con-verted to sugars by quccessive steps of cooking and ~reatment with acids and~or enzymes. ~he temperature and acidity are adjusted and the resulting mash is placed in a fermenter tank and 'starter' yeast is supplied from an ou~side source.
In the fermenter tank, the yeast consumes ~he fermentable ~g~
~ug2rs and both propagates itself and produces alcohol. When the sugar ha~ been consumed, the alcohol is removed by distillation, and the non-fermentable materials are recovered for use as an animal ~eed product, usually as a single by-product called "Distillers Drled (;rains and Solubles".
This process may be improvecl in several ways by using the invention:
tl) Yeast may be recycled and this results in using shorter fermenta~ion time and smaller fermenters.
~2) ~ore alcohol is formed from the carbohydrate, since les~ yeast is grown.
( 3) A new ~y-product which contains high purity protein i8 produced.
Figure 3 outlines the traditional process, and Figure 4, the application of the novel proce~sO In the la~ter case, th~ coar~e insolubles (mostly cellulosic materials), and the fine in~olubles (mostly protein and fatty materials)are removed before fermentation. ~f~er fermentation, the yeast which is the only remaining insoluble material i~ recovered centrifugally and returned to the ~rmentera. Animal feed i8 produced by drying the coarse insoluble together with the solubles; no decanter i~ r~qui~ed after ~he stills, ~ince the insolubles have already been removed in earlier ~tep~0
Claims (13)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for obtaining from carbohydrate bearing grain high yields of soluble carbohydrates, protein fraction essentially free of carbohydrates, and ethanol which comprises, in combination the steps of:
a) steeping said grain in water for a period of time sufficient only to toughen the hull and germ thereof to facilitate subsequent separation and to form a steepwater;
b) separating said steepwater from said grain and concentrating said steepwater to produce feedstuff;
c) degerminating said grain and recovering germ containing oil and minimum amounts of starch and protein leaving a magma containing 75 to 30% by weight of water including minerals, proteins and carbohydrates and insolubles including starch, protein, fiber and fatty materials;
d) forming a slurry of said magma resulting from step (c) with water;
e) saccharifying the carbohydrates from said carbohydrate material to produce a sugar solution containing sugars, other water-soluble compounds and suspended coarse and fine insoluble materials;
f) removing the coarse insolubles from said sugar solution;
g) removing, washing and drying the fine insolubles comprising princi-pally protein from said sugar solution;
h) cooling and adding yeast to said sugar solution and fermenting same to produce ethanol;
i) recovering at least a portion of said yeast from said fermented material in (h) and recycling same for further fermentation;
j) distilling ethanol from the fermented material;
k) recycling water remaining after distillation to said solution and to wash said protein.
a) steeping said grain in water for a period of time sufficient only to toughen the hull and germ thereof to facilitate subsequent separation and to form a steepwater;
b) separating said steepwater from said grain and concentrating said steepwater to produce feedstuff;
c) degerminating said grain and recovering germ containing oil and minimum amounts of starch and protein leaving a magma containing 75 to 30% by weight of water including minerals, proteins and carbohydrates and insolubles including starch, protein, fiber and fatty materials;
d) forming a slurry of said magma resulting from step (c) with water;
e) saccharifying the carbohydrates from said carbohydrate material to produce a sugar solution containing sugars, other water-soluble compounds and suspended coarse and fine insoluble materials;
f) removing the coarse insolubles from said sugar solution;
g) removing, washing and drying the fine insolubles comprising princi-pally protein from said sugar solution;
h) cooling and adding yeast to said sugar solution and fermenting same to produce ethanol;
i) recovering at least a portion of said yeast from said fermented material in (h) and recycling same for further fermentation;
j) distilling ethanol from the fermented material;
k) recycling water remaining after distillation to said solution and to wash said protein.
2. The process of Claim 1 in which the magma remaining after steeping and degerminating is dewatered to reduce the amount of solubles which move for-ward in the process and the water expelled is recycled to wash said germ and to steep said grain.
3. The process of Claim l, wherein coarse insoluble materials are washed to remove the carbohydrates therefrom, leaving a sugar solution in which finely divided particles of protein and other finely divided particles are suspended.
4. The process of Claim 3, wherein the fine insolubles are recovered from the sugar solution by filtration or centrifugation.
5. The process of Claim 4, wherein after said sugar solution is freed of insoluble protein by filtration and/or centrifugation or other suitable means, said protein is separated from said sugar solution, dewatered (and dried) from about 88% moisture to about 60% moisture and the extracted water is recycled to said sugar solution.
6. The process of Claim 1, wherein said material is selected from the group of grain sorghum, wheat, barley, corn, rice, soybean, alfalfa, tapioca, potato, yams, and banana.
7. The process of Claim 1, wherein said sugar solution is converted to n-butanol, acetone, glycerol, lactic acid, butylene glycol, citric acid, glu-conic acid or itaconic acid.
8. A process according to Claim 1, in which the carbohydrate material is dry milled, the dry milled material is slurried with water, the carbohydrates are converted to a solution containing sugars, other water soluble compounds and suspended insoluble materials; removing therefrom a mash of coarse insolubles consisting mostly of protein; adding yeast to the remaining material to ferment same; centrifugally recovering said yeast; recycling said yeast for further fermentation; distilling alcohol from said material.
9. The process of Claim 1, wherein carbon dioxide produced during fermen-tation is recovered.
10. The process of Claim 1, wherein said slurry is (1) separated from steepwater; (2) said steepwater is concentrated to yield material suitable as feedstuff; (3) said slurry is degermed; (4) said germ is recovered while (5) the remaining underflow containing fibers, starch, protein, soluble and insol-uble materials is dewatered from about 80 to 50% water; (6) said underflow then being cooked; (7) cooled to saccharification temperature; (8) its pH adjusted to 4.0 to 4.5 and (9) from 1 to 1.5 liters of amylase per ton of dry starch is added.
11. The process of Claim 1, wherein said sugar solution is concentrated to form syrup, cast as solid sugar or crystallized as dextrose.
12. The process of Claim 10, wherein said fibers are removed dewatered, pre-dried to a moisture content of 20 to 40%, mixed with said concentrated steep-water and the resulting mixture is dried to form feedstuff.
13. The process of Claim 1, wherein said grain is corn and said steeping lasts ten to thirty hours.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000410574A CA1190497A (en) | 1982-09-01 | 1982-09-01 | Process for making fermentable sugars and high protein products |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000410574A CA1190497A (en) | 1982-09-01 | 1982-09-01 | Process for making fermentable sugars and high protein products |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1190497A true CA1190497A (en) | 1985-07-16 |
Family
ID=4123510
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000410574A Expired CA1190497A (en) | 1982-09-01 | 1982-09-01 | Process for making fermentable sugars and high protein products |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1190497A (en) |
-
1982
- 1982-09-01 CA CA000410574A patent/CA1190497A/en not_active Expired
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