PROCESS FOR SEPARATION OF DRY FOOD AND FEED MATERIALS USING A TRIBO-ELECTROSTATIC SEPARATOR DEVICE

Abstract

A process for fractionating a feed mixture derived from dried brewer's spent grains (BSG) or distiller's grains (DDG) or distiller's dried grains and mixed with solubles (DDGS) is disclosed. The process includes using a single-step tribo-electrostatic separation process and device to separate the feed mixture by supplying the feed mixture to a tribo-electric separator and simultaneously charging and separating the feed mixture into at least two subfractions, with one of the subfractions having a protein composition higher than the feed mixture and higher than that could be obtained otherwise.

Claims

1. A process for fractionating a feed mixture derived from dried brewer's spent grains (BSG) or distiller's grains (DDG) or distiller's dried grains and mixed with solubles (DDGS), comprising using a tribo-electrostatic separation process including: a. supplying said BSG or DDG or DDGS mixture to a tribo-electric separator; and b. simultaneously charging and separating said BSG or DDG or DDGS mixture into at least two subfractions, with one of the subfractions having a protein composition higher than the feed mixture and higher than that could be obtained otherwise.

2. The process described in claim 1 using a continuously operating tribo-electrostatic belt separator comprising: i. a first electrode and a second electrode arranged on opposite sides of a longitudinal centerline and configured to provide an electric field between the first and second electrodes; ii. a first roller, or rollers, disposed at a first end of the separator iii. a second roller, or rollers, disposed at a second end of the separator iv. a continuous belt disposed between the first and second electrodes and supported by the first roller(s) and the second roller(s) v. a separation zone defined by and between the continuous belt.

3. The process described in claim 1, wherein protein particles are separated from fiber particles for a feed mixture with protein level between 10-40%; and the oil content is less than 20%, and moisture content is less than 30%.

4. The process as claimed in claim 1, wherein the protein level of one of the sub-fractions is enriched to be anywhere in a range of 4% to 90%.

5. The process as claimed in claim 1, wherein the protein level of one of the sub-fractions is enriched to be anywhere in the range of 25% to 60%.

6. The process as claimed in claim 1, wherein the protein level of one of the subfractions is enriched by at least a relative change of 5%.

7. The process as claimed in claim 1, wherein the particle size can be anywhere in a range from 12 micron to 400 microns.

8. The process as claimed in claim 1, wherein the median particle size can be anywhere in a range from 187 micron to 320 microns.

9. The process as claimed in claim 1, wherein the moisture percentage can be anywhere from 0% to 10%.

10. The process as claimed in claim 1, wherein the oil percentage content can be anywhere from 0.7% to 12.0%.

11. The process as claimed in claim 1, wherein the feed mixture can be processed at a rate of anywhere in a range of 40 to 17,000 kg per hour per meter of TBS electrode width.

12. The process as claimed in claim 1, wherein the belt speed can be anywhere in a range of 10 to 70 feet per second.

13. The process as claimed in claim 1, wherein the electric field strength can be anywhere in a range of 120 to 4,000 kV/m.

14. A process for fractionating a feed mixture derived from oilseed meals using a tribo-electrostatic separation process, comprising: a. milling said oilseed mixture to a coarse particle size; b. drying the coarsely milled oilseed mixture; c. supplying the milled and dried oilseed mixture to a tribo-electric separator; and d. simultaneously charging and separating said oilseed mixture into at least two subfractions, with one of the subfractions having a protein composition higher than the feed mixture and higher than that could be obtained otherwise.

15. The process as claimed in claim 14, wherein the tribo-electric separator is a continuously operating tribo-electrostatic belt separator comprising: i. a first electrode and a second electrode arranged on opposite sides of a longitudinal centerline and configured to provide an electric field between the first and second electrodes; ii. a first roller, or rollers, disposed at a first end of the separator; iii. a second roller, or rollers, disposed at a second end of the separator; iv. a continuous belt disposed between the first and second electrodes and supported by the first roller(s) and the second roller(s); and v. a separation zone defined by and between the continuous belt.

16. The process as claimed in claim 14, wherein the oilseed mixture is sunflower meal.

17. The process as claimed in claim 14, wherein protein particles are separated from fiber particles for a feed mixture with protein level between 30-40%, wherein the oil content is less than 20%, and wherein the moisture content is less than 30%.

18. The process as claimed in claim 14, wherein the protein level of one of the sub-fractions is enriched to be anywhere in a range of 4% to 90%.

19. The process as claimed in claim 14, wherein the protein level of one of the sub-fractions is enriched to be anywhere in the range of 30% to 60%.

20. The process as claimed in claim 14, wherein the protein level of one of the subfractions is enriched by at least a relative change of 5%.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0023] Certain illustrative features and examples are described below with reference to the accompanying figures in which:

[0024] FIG. 1 is a schematic of a tribo-electric belt separator system; and

[0025] FIG. 2 is a ternary diagram representing composition ranges of various crops and feeds.

[0026] The advantages of the aspect and embodiments of this disclosure may be better understood by referring to the following description when taken in conjunction with the drawings. The drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. It will be recognized by the person of ordinary skill in the art, given the benefit of this disclosure, that the dimensions, sizes, components, and views shown in the figures are for illustrative purposes. Other dimensions, representations, features, and components may also be included in the embodiments disclosed herein without departing from the scope of the description.

DETAILED DESCRIPTION

[0027] The disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. Aspects of the disclosure capable of other embodiments and of being practiced or of being carried out in various ways. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of including, comprising, or having, containing, involving, and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. At least one aspect of the present disclosure is directed to a tribo-electric enrichment process and system for the enrichment of protein content from low value by-products such as, for example, those resulting from the brewing, Brewer's spent grains (BSG) and distillation industries, dried distiller's grains with or without solubles (DDGS or DDG) and to the resulting products from the process, particularly the product that is enriched in protein. The higher protein content products can have increased value as an ingredient in animal feed formulations.

[0028] In particular, at least one embodiment of the process includes supplying a DDGS/DDG feed mixture to a tribo-electric separator; charging and separating the feed mixture into at least two sub-fractions, with one of the subfractions enriched in protein and having a composition different than the feed mixture. In at least one embodiment, the protein concentration of one of the products of the separator apparatus and process is higher than would otherwise be achievable with the prior art processes or that is naturally occurring.

[0029] Corn DDGS/DDG feed produced by conventional methods contains less than 34% protein (usually less than 30% protein). U.S. Pat. No. 8,227,015B2 discloses a process to extract minor amounts of residual oils from DDGS to raise the protein to a maximum of about 35%. It is an object of this disclosure to provide process DDGS and DDG feed mixtures to increase the protein concentration. According to at least one embodiment, it is an object to process such feed mixtures to provide subfractions having a protein composition of at least 40%. According to at least one embodiment, it is an object to process such feed mixtures to provide subfractions having a protein composition of at least 50% protein.

[0030] FIG. 2 shows a ternary diagram representation of the typical range of compositions (protein, total fiber, starch/sugars/other carbohydrates) for naturally grown materials in the major categories of food and feed ingredients. For purpose of clarity, FIG. 2 does not display the moisture and oil content that was present in the mixtures during processing. The protein content of food and feed materials is measured using the standard Kjeldahl or Dumas methods. The total fiber content is measured using one of the standard analytical methods such as the gravimetric method AOAC 991.43. The total starch and sugars are measured by polarimetry and various other methods or calculated. The oil content is measured using the standard acid hydrolysis/ether extract method. The moisture content is measured using the oven drying method. The composition for each of the three solid phase components is expressed as a percentage excluding the water and oil fractions.

[0031] Each of the green squares represent the composition of a particular crop that is used as a food ingredient or animal feed product. The soluble fiber content for these example crops is not included in the fiber measurements. The blue squares represent composition of the feed materials used in exemplary tests of separating such feed materials using the TBS apparatus and process of this disclosure. The red squares represent the composition of the product and by-product materials produced for each example separation. The dashed arrows indicate the range of composition achieved from each example test separation of a feed material. It is important to note that the feed materials used for the example separations using the TBS apparatus and process contained various amounts of water and oil, and that the feed material input and the resulting outputs are presented as % protein, % insoluble fiber, and % starch/sugar/other carbohydrates, normalized to 100% by ignoring the water and oil content for each sample.

[0032] Examination of FIG. 2 reveals that the range of exemplary feed materials and outputs that separated using the TBS apparatus and process of this disclosure form a region that includes most of the various crops (green squares) that are used as food ingredient or animal feed products. Thus, it is reasonable to assume that the TBS separation apparatus and process can be used for the other example crops shown (and not shown in FIG. 2) that both fall within the region that were tested in the examples and it is also reasonable to assume that the crops that are not within the illustrated regions would also be able to be separated by the TBS apparatus and process to yield similar results given the limited number of tests that were run (not of all the crops were subjected to testing). Thus, as is evident from the examples and discussion, it is reasonable to conclude that the TBS process and apparatus of this disclosure can be used on naturally occurring crops (as well as pre-processed crops) other agricultural products, by-products, and waste materials having a moisture content and/or an oil content, at commercially significant processing rates to simultaneously charge and separate the crops into two streams each enriched in at least one of protein, fiber or starch.

[0033] The present disclosure relates to a novel process for fractionating granular food and animal feed materials that exist in the regions depicted in FIG. 2 into their constitutive components using the tribo-electric belt separator (TBS) and process. The apparatus of FIG. 1 and the process are effective at processing dry, granular food and feed materials in a single-step separation process, as a continuously operating process, at commercially significant processing rates. By single step process, what is meant is that the constituents to be a separated are simultaneously tribo-electrically charged, conveyed and separated. The process is applicable to the fractionation of various cereal grains, pulses, oilseeds, cocoa, coffee, and other agricultural products, by-products, and waste materials. The process has particular application in the enrichment of protein content of food and feed materials by separating the protein particles from starch and sugar particles, and separating protein particles from fibers. Aspects and embodiments of the process have a particular benefit for the separation of dried distiller's grains resulting from the brewing and distillation industries mixed with solubles (DDGS) to enrich the protein content of at least one of the resulting products from the process. Another application is in the enrichment of starch content in food and feed materials by removal of residual fiber and protein. Other applications include consequential enrichment of various health promoting components, such as beta-glucan. In other embodiments of the invention, other constituents of natural materials may be enriched or separated from a mixture containing micronutrients, vitamins, trace elements, color, phytochemicals, or minerals.

[0034] The TBS operates as a single-step device where the food and feed particles are simultaneously tribo-charged by the frequent particle to particle collisions that occurs in the single device through the action of the special high-speed continuous-loop belt, conveyed and separated. Electrostatic separation processes based on tribo-charging are superior, and have wider application, than those based on charging by conductive induction or ion bombardment because separation can be achieved for a larger variety of particles with subtle differences in surface chemistry (or surface work function). Because the particle number density is so high within the electrode gap and the flow is vigorously agitated by the high speed belt, there are many collisions between particles in the device, and optimal tribo-charging occurs continuously throughout the separation zone. The counter-current flow induced by the motion of the continuous-loop belt creates counter-current multi-stage separation within the TBS device.

[0035] In contrast to the TBS apparatus and process according to this disclosure, vertical plate electrostatic separators all require a separate upstream processing step to tribo-charge the feed particles prior to separation by the vertical plate separator. For vertical plate separators, the tribo-charging step may require that each particle contacts a special solid surface with particular surface properties to enable differential charge to develop on the surface of particles. However, the need for each feed particle to contact a special solid surface creates a significant limitation on the maximum processing rate that can be achieved with a vertical plate separator for a compact device.

[0036] An issue with separating food and feed materials is that they tend to be cohesive powders that adhere especially well to the surface of the electrodes needed to create the electric field in an electro-static separator. An advantage of the motion of the high speed continuous loop belt in the TBS device and process of this disclosure is that it continuously scrapes the electrodes, which aids in removing the cohesive feed and feed materials from the electrodes and depositing them in the appropriate product hopper. The high speed continuous loop belt is the only moving part in the TBS device and process, and by its design and high speed motion it simultaneously conveys and tribo-charges the feed material, and the belt also provides a system to continuously clean electrodes of cohesive feed and feed materials that adhere to the electrodes. This feature enables the TBS apparatus and process of this disclosure to operate continuously without the need for complex electrode scraping mechanisms or electrode polarity switching systems that are required for vertical plate processes.

[0037] One advantage of the TBS apparatus and process of this disclosure, as illustrated by the test examples disclosed herein and illustrated in FIG. 2, is that the TBS apparatus and process can be used to separate feed materials, often in their naturally occurring state with their naturally occurring moisture and oil content (that little to no pre-processing is necessary) to achieve separation of the feed content into two enriched streams of at least one of protein, fiber or starch. It is also appreciated that the moisture content of feed material for the TBS apparatus and process can be adjusted to a range that optimizes the particle tribo-charging and therefore optimizes the resultant separation results. The optimal moisture level can depend on the nature of the feed material and will typically vary between 0% and 30%, and preferably between 0.2 and 11%. Adjustment of feed moisture is advantageous for some food and feed materials, but it is not a necessary requirement to adjust the moisture level of food and feed materials to achieve satisfactory separation results for some materials using the TBS device and process of this disclosure. For example, in the example described below, the separation results were achieved when processing feed materials as-received, that is with moisture levels as occurred naturally in the growing, harvesting, and milling process. This observation demonstrates a unique feature and advantage of the TBS apparatus and process of the disclosure, which is that the single step tribo-charging and separating that occurs in the TBS process is adequate to charge the individual components to be separated without the need for a preliminary feed drying, or wetting, or a separate tribo-charging step.

[0038] According to aspects and embodiments disclosed herein, the TBS device and process can be operated with belt speed between 10 and 70 feet per second, preferably between 45 and 65 feet per second; the voltage applied to the electrodes of the TBS apparatus and process electrodes can vary between 3 kV and 20 kV, preferably between 10 and 16 kV; that the gap between the electrodes is continuously adjustable and can be varied between 0.5 to 2.5 cm, preferably between 0.9 to 1.7 cm.

[0039] Examples of separation results obtained from sat least one feed materials are detailed in the following example, and the ranges of products and by-products achieved for each example is shown graphically in FIG. 2.

Example 1: Enrichment of Protein from DDGS

[0040] A sample of corn-based distillers dried grains with solubles (DDGS) was prepared for testing using the TBS apparatus and process to demonstrate the capability of the TBS apparatus and process to simultaneously charge and separate distinct protein and starch particles using the TBS apparatus and process in a single step. The sample was milled using a hammer-type mill to a median particle size of approx. 187 micron, contained 8.8% moisture after milling. The sample contained approximately 6% oil, as measured by the ether extraction method. The feed sample was fed as-received, with no adjustment to the moisture content, into the TBS separator at a rate of 40 kg per hour per meter of TBS electrode width. The TBS belt speed was set at 45 feet per second, and 8 kV was applied across the TBS electrode gap to produce an electric field strength of 790 kV/m. Two resulting products were collected from the two ends of the separator. There was no middling fraction that needed to be re-processed. The mass yields of the two products, the composition of the feed and the products are shown in table 1 below:

TABLE-US-00001 TABLE 1 Results from testing corn-based DDGS Product 1 Product 2 Run ID (Enriched (Enriched 190423-X3.7-1 Feed Fiber) Protein) Mass 100% 46% 54% Protein 33.6% 24.9% 40.7% (dry basis) Moisture 8.8% Fiber (ADF) 9.9% 11.4% 9.0% Fiber (NDF) 23.4% 32.8% 15.6% Oil 6.4% % % Starch 5.7% 5.0% 6.6% Fiber (NDF) 64% 36% Recovery Protein 34% 66% Recovery
This example demonstrates the capability of TBS process to effectively tribo-charge and separate distinct protein and fiber particles in a single step from a DDGS feed sample in fine dry powder form, generating product streams enriched in each component.

Example 2: Enrichment of Protein from Brewers Spent Grain (BSG)

[0041] A sample of brewers spent grain was prepared for testing using the TBS apparatus and process to demonstrate the capability of the TBS apparatus and process to simultaneously charge and separate distinct protein and fiber particles using the TBS apparatus and process in a single step. The sample was milled using a hammer-type mill to a median particle size of approx. 320 micron, contained 4.8% moisture after milling. The feed sample was fed as-received, with no adjustment to the moisture content, into the TBS separator at a rate of 71 kg per hour per meter of TBS electrode width. The TBS belt speed was set at 45 feet per second, and 8 kV was applied across the TBS electrode gap to produce an electric field strength of 790 kV/m. Two resulting products were collected from the two ends of the separator. There was no middling fraction that needed to be re-processed. The mass yields of the two products, the composition of the feed and the products are shown in table 2 below:

TABLE-US-00002 TABLE 2 Results from testing Brewers Spent Grain Product 1 Product 2 Run ID (Enriched (Enriched 190716-X3.7-2 Feed Fiber) Protein) Mass 100% 63% 37% Protein 25% 15.9% 42.9% (dry basis) Moisture 4.7% Fiber % % Ash % % Oil Starch Fiber Recovery Protein 39% 61% Recovery
This example demonstrates the capability of TBS process to effectively tribo-charge and separate distinct protein and fiber particles in a single step from a spent grain feed sample in fine dry powder form, generating product streams enriched in each component.

Example 3: Enrichment of Protein from Coarsely Milled Sunflower Meal

[0042] A sample of sunflower meal was prepared for testing using the TBS apparatus and process to demonstrate the capability of the TBS apparatus and process a coarsely milled sample of sunflower meal to simultaneously charge and separate distinct protein and fiber particles using the TBS apparatus and process in a single step. The sample was milled using roller-type mill to a median particle size of approx. 415 micron. After milling the sample was dried in a separate step to a moisture level of 2.7% moisture. The feed sample was fed, into the TBS separator at a rate of 12,000 kg per hour per meter of TBS electrode width. The TBS belt speed was set at 15 feet per second, and 12 kV was applied across the TBS electrode gap to produce an electric field strength of 1225 kV/m. Two resulting products were collected from the two ends of the separator. There was no middling fraction that needed to be re-processed. The mass yields of the two products, the composition of the feed and the products are shown in table 3 below:

TABLE-US-00003 TABLE 3 Results from Sunflower Meal Testing Product 1 Product 2 Run ID (Enriched (Enriched 190730-A2 Feed Fiber) Protein) Mass 100% 36% 64% Protein 40.7% 17.6% 51.7% (dry basis) Moisture 2.7% Fiber % % Ash % % Oil Starch Fiber Recovery Protein 16% 84% Recovery
This example demonstrates the capability of TBS process to effectively tribo-charge and separate distinct protein and fiber particles in a single step from a coarse roller-milled sunflower meal feed sample in coarse dry powder form, generating product streams enriched in each component.

[0043] It is appreciated that any embodiment disclosed herein may be combined with any other embodiment in any manner consistent with at least one of the objects, aims, and needs disclosed herein, and references to an embodiment, some embodiments, an alternate embodiment, various embodiments, one embodiment or the like are not necessarily mutually exclusive and are intended to indicate that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment. The appearances of such terms herein are not necessarily all referring to the same embodiment.