H1GH-PR0TE1N FOOD MADE FROM GRAIN AND METHOD OF MANUFACTURE THEREOF

FIELD AND BACKGROUND OF THE INVENTION

This invention relates to the field of high-protein food materials and the manufacture of such material from grain. In particular, the invention relates to a food product suit¬ able for human consumption and substantial ly free of fibers, fats, and oi ls, the product being made from grain from which fermentable sugars have been largely extracted but having a higher protein fraction than any untreated grain, the pro¬ tein fraction including effective amounts of all of the es¬ sential amino acids.

DESCRIPTION OF THE PRIOR ART

There is currently a critical and increasing world food shortage. It is not only necessary that nations find ways to increase and to use effectively the total quantity of food available in the world but that the additional food have proper nutritional values. In particular, extra sources of protein a re needed, since protein is the most important foodstuff.

The derivation of high-protein foods and food supplements from plants has been the subject of extensive investigation Soybeans have long been known to be a good source of edible protein, and have been the subject of much study, but it is difficult to remove the basic bean taste from foods pro-

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cessed from soybeans, and therefore, soybean-based food continue to be less desirable than their nutritional pro file indicates that they should be. Cereal grains also contain substantial amounts of protein but generally hav less nutritional value than soybeans. However, foods ma from grain a re not plagued by an undesirable taste.

There is a source of grain heretofore overlooked as bein fit for human consump ion. Substantial quantities of gr are used in the brewing industry and at the present time there is In excess of 1.5 mill ion tons of spent grains p duced each year as a by-product of the brewing industry i the United States and four times that amount world-wide. The grains are referred to as "spent" because a large pe centage of fermentable sugars has been extracted from th leaving material that is of no further value in the prod tion of beer. This material, when dried, consists of needle-sharp particles due to the husks of the grains an especial ly because of these husks, is not suitable for h man consumption but is currently being sold as cattle fo at a price of about one cent a pound on a dry basis. Th removal of spent grains from the brewery poses potential , and sometimes actual, logistical problems, and spent grai are generally looked upon in the brewing industry as an undesirable but unavoidable waste material.

The husks of grain processed for direct human consumption as cereals, flour, etc. a re not so troublesome because th are removed while the grain is still in the raw state. I that state, the husks are not bound, tightly to the grain and are relatively easily removed. By the time grain has gone through the mashing process used to extract ferment¬ able sugars in the production of beer and other alcoholic beverages, the husks have been cooked onto the grain, fo ing a tenacious adhesive bond between each seed and its husk. This has heretofore presented an insuperable barri

to the use of brewers spent grains as a human food material, although the digestive system of cattle permits dried spent grains to be used as cattle food, for which brewers are pa id very 1 ϊ ttle.

The initial process steps appl ied to grain in brewing beer and the l i e result in the production of large amounts of undesirable sewage, the removal of which is enti rely an ex¬ pense. Not only are brewers required to pay high sewer taxes to the communities in which breweries are located, but because of thei r inabi l ity to control the quantity and nature of the material they del iver to the sewage system, the brewers also have to pay high sewage surcharges.

SUMMARY OF THE INVENTION

I t is one of the objects of this invention to provide a food formulation that has a high-protein percentage and is subs an ial ly free of fibers, fats, and oi ls.

It is another object of the invention to obtain a food hav¬ ing high protein content by removing fermentable sugars from grain and treating the resulting spent grains to re¬ move the husks and fats and oi ls.

A particular object of the invention is to uti l ize brewers spent grains in the production of a high-protein food fit for human consumption.

Sti l l another object of the invention is to provide a pro¬ cess for removing the husks of grain that has been cooked, and particularly grain that has been subjected to a mashing operation as part of a brewing operation.

A sti l l further object of the invention is to produce a food product suitable for human consumption from brewers

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spent grains without the use of chemical additions or adu terants .

Stil l another object of the invention is to evaporate fr brewers spent grains moisture that would otherwise have be drained as a l iquid into the sewer and be treated at high cost by a sewage disposal plant.

Further objects will become apparent from the following spec I f i cat i on .

In accordance with this invention grain, subjected to a mashing operation, is dried by the appl ication of microw energy, preferably accompanied by mechanical agitation, is then subjected to extremely low temperature to embrit the husks whi le the latter are mechanical ly fractured fr the grain. After that the husks and grain are physical l separated from each other, and the fats and oils in the grain are separated out by. a solvent, leaving a granular material having a high proportion of protein. This mate al can be ground to various degrees of fineness as desi r for processing into different kinds of food products.

BRIEF DESCRIPTION OF THE DRAWINGS

The only drawing is, basical ly, a flow chart of the equi ment and process of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

As the source of enzymes for mashing, and because of its decisive influence on the characteris ic taste of beer, barley malt is the one ϊ ndespensabl e brewing material . Malting is simply the control led germination of grain, t germination being stopped at a desired stage by means of heat. The purpose of malting the barley is to develop t

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dor aπt enzymes of the barley so that they can break down the carbohydrates and release the fermentable sugars. Malt¬ ed barley has a yield of soluble substances of about 72% to 762, dry basis, which is about five-fold or six-fold increase over the yield of un alted barley.

The initial stage in the brewing operation, proper, is the mashing stage in which malted barley, usually referred to simply as malt, that has been crushed between rollers is mixed with water in large tubs until it forms a mash having the consistency of porridge. The malt can be used alone in forming the mash, and in Germany, for example, this is man¬ datory. In other countries, for example the United States of America, adjuncts, such as corn grits or flakes or rice or other materials having high percentages of fer eπtab 1 es , can be added. Malt and adjunct are stored in bins 11 and 12 before being used. fπ the case of corn grits and rice, these adjuncts must be gelatinized by being boi led in a cooker 13 before being added to the mash in a mashtub 1 . Corn flakes, having been subjected to pre-gelat.inizatϊon, require no further boil ing but can be added directly to the mash .

The mash is heated in steps going from about 38° C ^t0 about 7 ° C in a cycle of operation chosen by the brewer. The cycle is normal ly divided into steps to allow various en- zy es to act at the temperatures best suited to such ac¬ tions. Thereafter, the spent grains settle to the bottom of the tub to form a fi lter bed through which the l iquid, cal led "wort," is filtered, or lautered.

One of the reasons for using barley is that the structure of the barley husks makes the bed of spent barley grains especially suitable as a filter. If the mashing operation just described were appl ied to a different grain, not so much for the purpose of producing wort and eventual ly beer

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but more specifically for the purpose of producing spent grains having the highest possible protein content by usi grain having the highest available natural protein, it might be necessary to provide additional filtering means allow the wort to be removed without washing away the spe grains. The choice of grain to be used may well be eco¬ nomically dictated by the fact that the profit that can b made by a brewer from the high protein material made by t process of this invention may be greater than the profit obtainable from the beer produced from that grain. In short, the by-product may become the main product and vic versa .

After lauteriπg, sparge water is flushed through the spen grains and is combined with the wort. Sparging is contin ued until analysis of the sparge water shows only about one percent or one and a half percent of extract. The be of spent grains having a moisture content of about 75* to 80 % must then be removed from the tub as quickly as possi ble to permit a fresh batch of malt to be put in to start - a new mashing operation. While the fastest way of dispos ing of the spent grains might be to wash them down the se er, the enormous load that this would place on the sewage disposal system makes this method of disposal impractical

The usual practice is to haul the soggy mass of -spent grains away from the brewery in large trucks as soon as a mashing operation has been completed, although some brewe ies store the wet grains in storage tanks and do not use trucks. Any delay In removing the spent grains from the mashtubs quickly brings the brewing operation to a halt, and if trucks are used, it is preferable to have the truc waiting at the brewery prior to the end of each operation even if this is not the most efficient use of the trucks.

The spent grains are stored for later use as cattle feed

but before being stored must be dried. The conventional drying method used at the present time is to remove the surface effluent from the soggy spent grains by a dewater- ing screen and then to subject the spent grains to the squeezing mechanical action of a Davenport press to effect further moisture reduction. Virtually all of the effluent removed by this conventional technique goes into the sewer and places a substantial load on the sewage disposal system.

Even though the drying operation usually takes place away from the brewery (it could be carried out at the brewery before the spent grains are hauled away), a large percent¬ age of the sewer tax the brewery is required to pay is cal¬ culated on the basis of the effluent removed in the drying operation. The sewer surcharge that must be paid by the brewery is a function of four pollutants, the worst of which is the spent grains effluent resulting from the dry¬ ing operation. The others are: beer spillage, yeast spill¬ age, and caustic (PH treatment).

In determining the spent grains effluent, no physical mea- sure ent of the volume or weight of spent grains produced at the brewery is made. Instead, the surcharge is deter¬ mined, usually, in one of two ways. One way is to weigh the amount of malt and adjunct that enters the plant and to measure the water input in cubic feet. The figures thus obtained are put into an equation that considers the pro¬ cess at the brewery and determines the amount of effluent that will go into the sewer. The brewer is billed accord¬ ingly.

Another way is to use an effluent sample that operates as a "in-line sample" to take composites of the effluent grain line over a period of time. The B.O.D. (biologic oxygen demand) of the effluent samples, and the amount of malt, adjunct, and water purchased are used to calculate the sew-

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er surcharge. If the B-O.D. in the samples exceeds a mi imum value, an additional fine is added to the basic sew tax. Even when the grains are dried at a location away from the brewery, the tax surcharge is made to the brewe because the calculation includes the brewers' raw materi In addition, there is always some grain washed into the sewer when the mash tubs are cleaned and some more due t washings from the conveyors, but these amounts are small compared to the effluent that comes from the drying oper ation.

At the present ime, the handling of spent grains is bei subjected to an increasing amount of direct environmenta control, as well as indirect control through taxation, b communities in which breweries are located. A brewery h ing a capacity of a million barrels can deposit, through effluent grains waste, enough polluting material to requ the same amount of sewage water treatment as would be re quired by a town having a population of 25,000 citizens. Most towns today require installation of a total recover system that, in essence, evaporates all of the water fro the spent grains and incorporates a sludge removal syste with chemical treatment. This imposes heavy fuel costs the brewery, virtually eliminates pressing operations us up to the present time, and triples the drying operation in conventional cylindrical rotary drum driers used here tofore.

Communities are also becoming increasingly concerned abo air pollution. Special afterburners are being required be installed to burn off all of the fine dust particles that pollute the air and produce an odor in the vicinity of the brewery. The cost of fuel for total recovery sys tems is four times as expensive as the cost for standard systems used for the past fifty years but which are now being outlawed by more and more cities. Furthermore, th

pol lution control equipment in existence up unti l now re¬ quires a great deal of space and operates slowly.

In accordance with one aspect of this invention, the soggy spent grains are not hauled away from the brewery. Instead, they may be temporari ly stored in a container 16 or else transferred directly to a conveyor 17 which carries them directly through an industrial microwave drier 18 operating at a frequency and output power high enough to impart suf¬ ficient energy to vaporize the moisture contained within the grains. Whi le the grains are passing through the mi¬ crowave drier 18 on the conveyor 17 they are also subjected to mechanical vibration by a vibrator 19 to make it easier for the moisture to escape. The Federal Communica ions Commission has authorized frequencies of 915 MHz and 2^50 MHz for microwave drying equipment, and the higher of these frequencies is preferable for initial drying operation, but other frequencies may be used when and if thei r use is au¬ thor i zed .

Drying the spent grains by microwave energy results in great financial savings to the brewer in reducing the spent grains effluent portion of the sewer tax and surcharge. A brewery paying an annual surcharge of $700,000 due to ef¬ fluent grains pol lution could el iminate that charge, al¬ though the brewery would have to pay about one-tenth of that amount as addi tional annual uti l ity cost. The cost of install ing the microwave driers would be about $500,000.

A pecul iar aspect of brewers grains is that the concentra¬ tion of moisture is not on the surface, as i t is in almost al l other products, but is trapped inside the kernels of the grain so that it is quite difficult to remove quickly and inexpensively. Microwave energy is absorbed by the electrical ly bipolar water molecules in the kernels to bring the temperature of the water in the wet grains rapid-

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ly to 100° C. None of the microwave energy is wasted in heating the air or the spent grain material, so that the electric power required to generate the microwaves is ve efficiently util ized. The drying time is reduced by as much as 8 ? in comparison with hot air drying, and the m crowave drier occupies only about 25? of the space requi for a hot air drier. Simply because of the length of ti the spent grains have to remain in a conventional drier, such drier lose more than half of the heat generated and therefore, more than half of the power suppl ied from the power 1 ines .

Because microwave energy removes the water quickly and without raising the temperature of the grains excessivel it does not adversely affect the nutritional value, or p file, of the grains. All of the normally effluent water transformed into steam, thereby eliminating a major poll tion problem of the brewing industry.

Removal of such high moisture content by application of microwave energy is also unique because there are very f products that have an 80? moisture content prior to dryi A 35? moisture content in a material to be dried is con¬ sidered quite high.

I have found it preferable to divide the microwave heati into two separate stages. In the first stage the perceπ age of moisture in the grains is reduced from the Initia approximately 80? value to about 12? to 30? and preferab to about 20?. I have found that the use of microwave en ergy achieves this reduction in moisture content in the same length of time that would be required to reduce the moisture from the 80? level to 75? In a conventional hot air dryI ng system.

After passing through the first microwave heating unit 1

the partially dried grains enter a fluffing chamber 21 in which the grains are further agitated by warm air currents for surface rotation. This fluffing operation has been found to be very beneficial in helping to dry the grains quickly without adversely affecting the nutritional profile.

After being fluffed, the grains are conveyed, as part of the continuous drying process, through a second microwave drier 22 by a conveyor 23 to reduce the moisture content further to approximately 6? to 10? and preferable, to 8?, which is the desired amount for storage of the grains. Grains having more than 8? moisture become rancid more quickly; those having less than about 8? are more subject to catching fire. The conveyor 23 is also oscillated me¬ chanically by a vibrator 2k while passing through the drier 22 to aid in releasing vaporized water from the vicinity of the grain. Since less energy is required to effect moisture removal in the second microwave dried, the micro¬ wave frequency can be lower, for example, the standard 915 MHz, or other frequencies, if they are authorized. This double microwave system achieves a high degree of uniformi¬ ty of the dried grains and maintains the nutritional pro¬ file. The water is removed as steam, and there are no wastes or pollutants.

A further advantage of the use of microwaves in drying is that they sterilize the product. Salmonella and Staphlo- cocci are killed by microwave heat, and any insect eggs are also destroyed. Such eggs may be produced in the spent grains by insects attracted to the soggy mass after it has left the tub ] and before it enters the microwave heating driers. Furthermore the soggy spent grains are an excel¬ lent medium for bacterial growth, and microwave energy elim¬ inates all bacterial problems.

Dried grains from the second microwave drier 22 are con-

veyed to a chamber 26 cooled to a very low temperature. This chamber may be a tower Into w ich the grains are fe at the top and cooled by a suitable cool ing medium, pre¬ ferably l iquid nitrogen, sprayed from a source 27 onto t fal l ing grains to come into momentary contact with them. Alternatively, the grains may pass through a l iquid nitr gen bath. In either case, the grains are brought to an exceedingly low, sub-freezing temperature and fed betwee mechanical rol lers 28 to be fractured by rubbing abrasiv action. The rol lers may be located at the bottom of the tower and may cons ist of a triple set of rol lers for opti mum operation. The grinds of these rol lers can be set f medium-coarse to fine.

Liquid nitrogen has several advantages. For one thing i provides the temperature necessary to separate the husks and fibrous fractions from spent grains, a procedure that could not be carried out satisfactori ly with conventional techniques used by mil lers. Standard mi l l ing operations are appl ied to grains that have not undergone a cooking process. The husks of uncooked grains a re relatively eas to remove, but the husks and fibrous material of spent grains are difficult to separate from the grains themselv because carbohydrate and protein material resulting from incomplete removal during the leaching and sparging pro- cesses in the brewery forms films that are sol idified dur ing the drying operation and act as an adhesive that bind the husks and fibrous materials more tenaciously to each seed. A relatively smal l amount of husks and fibrous ma¬ terial is already separated at the time the grains reach the rol lers 28 at the output of the cool ing tower 26, but the greater portion of the husks and fibrous material is bound to the grains by means of the fi lms just described.

Although it is the drying operation that sets the adhesiv film, it is the cooking operation in the mashtub 1 k that

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preceeded the drying operation that causes the fi lm to be generated. Yet the cooking operation is necessary, not only because f Is required to obtain the wort in producing beer but also because it is the part of the process that removes a substantial fraction of the total grain material and leaves the remainder with a higher protein percentage by virtue of the removal of the non-protein material .

The embr i tt lement of the grains by the l iquid nitrogen causes individual pieces of crushed grain to fracture quite easily in the rol lers 28, which makes it easier to dislodge the fibrous fractions from the grain pieces. The grain is kept at a very low temperature during the abrasive action to faci l itate the fracture between the grain and the fi¬ brous port i ons .

An additional important reason for choosing l iquid nitrogen as a coolant is that it is non-toxic. As i t evaporates, it simply becomes part of the atmosphere and has no i l l ef¬ fects on anyone who may-breathe it. It also has no i ll ef¬ fects on the grains being processed. Liquid ni trogen is commonly used in processing of frozen foods and thus repre¬ sents a material that has already been approved by appro¬ priate governmental agencies. tt cannot leave any residue or have any chemical reaction with the spent grains. It is readily avai lable and is economical to use and is general ly preferred for producing extremely low temperatures in food manufacturing operations. Its use in helping to fracture the pieces of crushed grain in the present invention is not to freeze the grains but to bring them to an extremely low temperature, thereby making the adhesive fi lm brittle.

The fractured material passes into an air-classification chamber 29, usual ly a vertical tower in which air is blown up through the fractured material , causing both the husks and the fractured grains to rise. The husks are less dense

and are therefore carried to higher points by the risin air so that they may be drawn off and stored in suitabl receptacles 31 for later use. The more dense granular terial is drawn off at lower levels from the a I r-class i cation chamber and. stored In a bin 32 for a period of a least kS minutes to three hours, but preferably at leas one hour, to allow settling of both the granular materi and dust.

The husks taken from the air-classification chamber rec tacles may be ground further according to specification furnished by a purchaser. Fibrous materials have recen become popular as food additives because of the benefici effects attributed to the Inclusion of fibers in human

After the grains have been allowed to settle, the fats oils are extracted by a suitable solvent in an extracti chamber 33- The solvent must be non-toxic and volatile as to leave no residue on the grains nor impart any und sirable flavor to them. Petroleum ether may be used as solvent, but hexane, which is well known as a solvent i the food industry, is preferred. The solvent Is passed through grains to dissolve the fats and oils so that th latter may be drawn off into a storage tank _\k, leaving fat-free grains that are also free of husks. These grai now devoid of husks, oils, and fats, a re In condition t ut through a milling and grinding operation in a grind 36, for example an alpine impact mill, with a special li quid nitrogen cooling chamber. The mill may be set to grind the fat-free grains into whatever particle size is desired by the purchaser and stored in sections of a co tainer 37 according to particle size. For example, bak ies will normally require grain ground into a flour, whi those manufacturers of meat extenders require a semi-co grind.

The material may be fortified at this stage to raise the protein content by yeast injection or to adjust the nutri¬ tional profile by the addition of suitable amino acids or to insert flavoring material of any desired type. These fortifications are not mutually exclusive, but instead, two or more can be carried out on the same granular mater¬ ial .

In the case of the addition of food flavors, the fact that the granular materials produced according to this invention have no strong taste of their own to be overcome, in con¬ trast to soybean material, is an advantage. Thus, any type of flavoring can be added, a fact that has been found to be unexpectedly important in the case of high-protein material to be furnished to people in certain countries. It has been found in the past that there are ethnic groups indi¬ genous to certain countries who insist upon certain flavors and reject other flavors, even though their total diet may be marginal in quantity, A lack of a pronounced adverse taste ϊ-n the material provided by the present invention makes it easy to satisfy the requirements of such people. Of course, the lack of an irremovable distinct taste that is unpleasant in certain combinations of tastes is advan¬ tageous in all kinds of food products.

After the grain has been fortified, if such fortification is considered necessary, it may be packaged or sent to a bulk storage location. It is preferable to limit storage to approximately 40,000 pounds per bin for safety and ig¬ nition considerations.

The quality of the protein material produced by the pro- cess just described is illustrated in the analysis in Table I. In this sample, the starting material had a relatively high amount of protein. However, even with lower initial protein, this invention enhances the concentration, and no

grain-based food haying a protein percentage in excess about 36? and free of fats and ofls and fibers has been known heretofore. The profile of the material represen in Table I In w-hich the protein is concentrated to 41? i typical of what may be expected from brewers spent grai obtained In north-eastern section of the United States. Proteins taken from grains In other parts of the country and in other parts of the world will vary to some exten but in all cases, the percentages of protein will be hig than has been obtainable in the past.

Not only is the total quantity of protein high, but the percentage represented by those a ino acids deemed bene¬ ficial to the diet Is also high. As may be seen, these amino acids, which are specifically named in Table I, ac count for about 35? of the total grain, and the addition approximately 6? of protein is protein that is not of pa ticular nutritional value.

TABLE \

NEW ENRICHED PROTEIN GRAIN

PROTEIN 41.0?

MOISTURE 8.0?

ASH (minerals) 4.0?

FATS S OIL

FIBER

CARBOHYDRATES 47.0?

AMINO ACIDS (Nutritional Profile)

Arginine 1.57? of the grain 3,8? of protein

Histidine .74 1.8

Isoleucine 1.50 3.7

Lysiπe .95 2.3

LeucIne 4.08 9 :

Meth ion ine .62 1.6

Phenylalanine 1.95 4.7

Threonine 1.19 2.9

Tryptophan .31 .76

Tyrosine 1.12 2.7

Valine 1.83 4.6

Aspartic acid 2.37 5.8

SerIne 1.55 3 8

Gluta ic acid 7.93 19 3

Proline 3.80 9 2

Glycine 1.15 2 8

Ala ^' nine 2.33 5 7

Table I I shows a protein profi le that has been deemed to represent a high-qual it protein. This table includes i formation taken from Recommended Dietary Allowances, ed . Washington, D. C. 1974, Food and Nutrition Board, Nationa Research Counci l , p. 44, as publ ished by Orten, J. M. and Newhaus, 0. W. , in Human Biochemistry, publ ished by the C. V. Mosby Company (1975) , p, 523- Comparison of the c umn titled "New Formulation," which represents the amino acid profi le of the high-protein food according to the pr sent invention, show-s that the profi le of the new formula tion compares- favorably with the desired pattern and has serious amino acid deficiencies.

This invention has been described in terms of specific materials and processes, but it wi l l be obvious to those ski l led in the art that modifications may be made therein within the scope of the invention as defined by the fol lo ing c1 a i s .

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TABLΕ I -

Amino acid pattern for New

Amino acid high-quality proteins Formu la i on g/gm of protein)

H i sti d Ine 17 18

1 so 1euci ne 42 37

Leuci ne 70 99

Lys i ne 51 23

Total S-contalning amino acids (Met, Cys) 26 16

Total aromatic amino acids (Phe, Tyr) 73 74

Threon i ne 35 29

Tryptophan 11 7.6

Va 1 i ne 48 46