CA2007031A1 - Method and apparatus for processing and using the seeds of leguminous plants at a feed-production factory - Google Patents

Abstract

ABSTRACT

The invention relates to a method and apparatus integrated in a feed-production factory for processing and using the seeds of field pea-type leguminous plants. The seed of a pea-type plant is dehulled in a hulling device, crushed in a crusher, and finely ground in a pregrinder and in a jet mill. The flour is air separated in air classifiers into two or more fractions so that the starch granules originating from cotyledon cells are substantially included in coarse fractions and the protein granules substantially in fine fractions.
For facilitating the fractionation, there is used a predetermined, selected variety of the pea-type leguminous plant. By effecting the grinding with a jet mill grinding technique it may be economically feasible to reach a sufficiently small particle size without subjecting the product to thermal injuries.
The process is integrated as a part of the feed production of a feed factory in a manner that at least some of the flour fractions are administered into a mixed feed being prepared. The invention includes proteinaceous pea feeds including at least 35% pea protein.

Description

Z~070~

The present invention relates to a method for processing and using the seeds of low-fat leguminous plants for feed-production, wherein a seed of leguminous plants is hulled and finely ground and the flour is then air separated into two or more fractions so that the starch granules originating from cotyledon cells are substantially included in coarse fractions and the protein particles substantially in fine fractions.
The invention relates also to an apparatus for processing and using the seeds of low-fat leguminous plants, said apparatus comprising a hulling device, a crusher, one or more fine grinders as well as air classifier means for separating the ground product into two or more fractions for including the starch granules substantially in coarse fractions and the protein particles substantially in fine fractions.
Leguminous crops, i.e. ripened seeds of leguminous plants, are commonly used for animal as well as human nourishment. Generally known leguminous crops include e.g. soya bean, pea, lupine and bean. The seeds of leguminous plants are known as sources of~vegetable protein. The protein of all leguminous plants is dietetically of high quality, being e.g. rich in lysin-amino acid whose content is known to be low e.g. in grain-containing food and feed. An example of the use of leguminous plants is the consumption of various soya products as a nutrient, e.g. in the form of 45% protein containing ground soya as a eed. The~productlon process of soya oil and gro~nd soya~is prior known and highly developed but such~process which is suitable for soya is uneconomical for pea which is of lower fat content.

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The prior known processes applied for enriching the protein of other leguminous crops, particularly that of field pea (pisum sativum), are technically and/or economically noncompetitive in view of the requirements of feed industry. They are are not feasible to be integrated in the processes at feed factories e.g. in wheat mill industry for producing valuable activated high-protein fractions from a pea raw material. Some separate specialized facilities which carry out fine-milling and air classifying peas and beans exist, but these facilities do not have capability as feed factories.
A common and traditional way of using the seeds of leguminous plants as a feed is to grind them as a whole in a similar manner to processing of grains, and to feed the pea meal to animals generally simultanaously together with other feeds, often prepared as mixed feed. While the dry normal pea seed contains approximately 20% of protein, this content is not as such sufficient to be utilized as an unsupplemented protein feed ingredient such as rape seed meal. Therefore, pea meal cannot be used as high-pr~tein feed ingredient to substitute soya bean meal in the production of feed mixtures, especially of feed concentrates.
The use of pea as animal feed is known to be limited by the fact that the~peas used as feed, ~as all seeds of leguminous plants,~contain certa;in so-called anti-nutritional substances de~teriorating in palatibility and in dietary~value,~ such as tannin, oligosaccharides, trypsin-inhibitor and lectin. It is known that the conte~t of these substances, the seeds of field peas (pisum sativum) is distinctly lower than in the~other leguminous ~
plants, e.g. soya. It has already been possible to ~; overcome considerably the effects of 20~70~

anti-nutritional substances by a selection of the field pea variety, which has taken place by plant breeders. It is thought that, in the near future, the plant breeders will be able to bring on the market certain new pea varieties, which have a markedly improved quality and which are especially suitable for fine grinding and air fractionating.
Also known, is that physically or chemically, such as by ethanol extraction and infrared treatment, it is possible to inactivate several anti-nutritional substances contained in leguminous seeds, such as trypsin-inhibitor. This inactivation may be carried out in such a manner that thermal denaturation of dietetically valuable protein is minimized.
Integration in a feed-factory environment of fine grinding and air classification effected by a dry process, or processing for improving the feed value of pea protein have not been heretofore practiced, studied or proposed. Dry processes for fractionating special products for use in food and chemical industries are available and applied in small specialized facilities e.g. in France and Canada. EIowever, ~the available processes have not been capable of providing economically competitive conditions for the mass production of protein-containing raw fractions required in eed factory like mass producing industry.
The pea seed is botanlcally completely different from e.g. cereal grains. The pod of legume, inside which the seeds grow;and ripen, is a fruit. The pea seed is surrounded by a readily removable seed hull (testa) whose dietetic value is clearly superior e.g. to that of cereal hulls~due to e.g. a low lignin content. Most of the pea seed, ~appro~imately 85%), is comprised of two large , semispherical seed leaves ~cotyledons) which have a non-differentiated ~uicy cellular texture reserve, the purpose of which is to serve as a supply and source of the reserve nourishment required for the initial growth of an embryo axis lying in the protection of the cotyledons.
The basis of the present invention is due to the generally known specific characteristics of pea seeds, that the starch granules inside the cotyledon cells are mostly separate both from each other and from other intra-cellular structural elements. This is dissimilar to the situation in, for example, cereal grains. Moreover, the starch granules of peas are distinctively larger in size than other material particles, such as proteins, contained in cotyledon cells. The protein content of pea seeds is generally more than 20% of the weight of dry matter, i.e. approximately double the amount contained in cereal seeds. It is generally known that the cellular texture of peas can be efectively broken down by and, usually, repeated grinding and that, thereater, a so-called wet extraction process or a dry, so-called air separation process may be applied for separating the larger sized pea starch granules substantially from other structural material in the cellular texture of peas. The integration of an industrially feasible fine grinding and air separation process of~pea into the operation o~ a feed producing factory has now been found possible by virtue~of~the fact that a 30~ feed-factory integrate is mat~eri~a1-wi~se technically and economically capable of e~ploiting all produced fractions in a preferred manner~. ;Another~available method is~a new jet-milling technique, whereby it is ~possible to instaIl and to carry~out the grinding in a limited space and in the already existing feed , factory facilities, as well as to ~ffect an .

2o07031 intensive disintegration of cellular textures with minor losses of quality. In view of environmental protection and material losses, it is economically and also technically preferable to employ the jet-milling and a direct, e.g. pneumatic material transfer when operating within one and the same feed-processing plant. If there is more profitable demand for some pea fraction elsewhere from feed-producing industry, a feed-producing plant can just as well sell any of the pea products to other pea buyers.
The Hankkija Plant Breeding Institute has been successful in breeding new field pea varieties and they have discovered such great differences in the intra-cellular texture of the seeds of different pea varieties that such differences may be technically and economically decisive in terms of both grinding and air separation properties of the field pea seeds. Prior studies have indicated that the more proteinaceous pea raw material is used, the higher protein content can be achieved in fine fraction by air separation. Examinations of the applicability of the invention have further indicated that the particle size distribution, which is typical of each variety of different pea varietîes and different from one variety to another, has an essential affect on the protein content of fine fraction. It is also known that plant breeding can be used to improve~tbe~dietary value~of pea 30 ~ material also in economical sense. This present process relates to the selection, contract farming and use of a particularly suitab1e pea variety, such as leguminous plants variety HOVI (HJA51850).
Thus, an aim of the invention is to ~provide an economically feasible method integrated : , : ~

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in the overall process of a feed-production factory for producing dietically valuable proteinaceous and starch-containing special flours and hull meal from the seeds of leguminous plants.
The invention also includes feed comprising a feed meal or flour comprising a proteinaceous fraction of an edible pea seed meal or flour containing at least 35% pea protein. Thus, in a method or a process of the invention, the initial procedure is the hulling and fine jet-mill grinding of a pea seed followed by air separating the flour into two or more fractions for including the starch granules originating from cotyledon cells substantially in coarse fractions and the protein particles substantially in fine fractions. A novel feature o the invention is the production wise economical integration of the method into the process of a feed-production plant, paying special attention to the quality of raw material, the use of a field pea variety developed and suited for this purpose, as well as the exploitation of per se known jet-mill technology for the fine grinding of pea.
The invention includes, in feed production processing equipment, apparatus for carrying out the process of the invention comprising the jets of particles are caused to collide with each other by means of compressed air used as a~working gas.
An embodiment of the~invention will now be described by way of example with reference made to the accompanying drawings in which the ~lone figure shows a schemetic view of one embodiment of an `-apparatus for carrying out the invention.
Referring to the drawing, the section between dash-and-dot lines l9 and 20 illustrates a pea processing apparatus of the invention, , integrated as a part of the production process of a 200~o~

feed-production plant. To the left of line l9 is a raw material receiving and storing station which may be operated by applying the normal grain receiving and storing technique already available at a feed-production plant as well as the factory laboratory facilities. The seed of a leguminous plant or variety suitable for the purpose of this method and acquired through farming contracts or otherwise can be analyzed prior to processing to separate from each other the batches having different protein levels. If necessary, the seeds are dried or otherwise pre-conditioned separately for the process and this can be done by using a method which simultaneously inactivates harmful substances, e.g. trypsin-inhibitors.
The selected and possibly pre-conditioned pea seeds are carried into an intermediate storage hopper 1. The first process stage comprises the removal of hulls from the pea seeds in a hulling device 2. The removal o hulls is a prior known simple procedure and can be effected by means of a simple device. The removal of hulls is not necessary in view of the present method but the fibre-containing hulls do not contribute to the quality of other obtainable products anyway. The digestible fibre containing pea hulls as such provide an interesting nutrient. The hulls may be recovered at hull recovery means 3.~
Hulled pea seeds are carried to a crusher 4. The crushed material is dried in the dryer device 5 which, if deslred, can also be used to effect a quality-improving heat treatment by the application of e.g. hot air or infrared radiation.
The crushed material is advanced into an intermediate storage hopper 6 for delivering it to a r plegrinder 7~ used for effecting ~a pre-communiution `: :
, 20070~1 to the particle size of about 100 - 200 ~m.
This is followed by effecting a final grinding to the particle size to less than 20 ~m by means of a jet-mill grinder 8. ~et-mill grinding employs compressed air energy for forcing the masses of material blasted from opposite directions to run into each other with a great force and to disintegrate themselves in a small grinding chamber. A jet-mill grinder 8 it is possible to use a counter jet mill grinder, for example a counter-jet mill grinder such as that developed by ~innpulva Oy. In such a grinder jets of particles accelerated by means of compressed air in jet tubes 9 are forced to run into each other in a small-volume grinding chamber 10. As particles run into each other with sufficient kinetic energy, the cell walls crumble for releasing the intra-cellular starch granules and protein particles. It is, of course, possible to employ also other types of jet grinders for delivering kinetic energy to the material to be ground through the intermediary of a working gas and the grinding proceeds as collisions between particles and a wall and~or as attrition between particles and a wall. Another alternative is to employ a per se known turbo-rotator grinding or pin-milling.
Jet-miil grinding technology has been :
earlier used in the grinding of minerals, pigments and also grains, such as wheat.~ Its~applicatio~n for 30 ~ grinding the seeds of a leguminous plant~is not known. The energy consumption of jet-mill grinding for a to~ of ground material is 4-6 times that o~
rod or rotor mills for the same weight. Therefore, it is a worthwhile economy to use it in pre-grinding. Moreover, a jet-mlll grinder does not , have moving parts and, therefore, there is very . ~

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little wear or need for maintenance. The jet-mill grinder also requires considerably less space than other grinders and, thus, its mounting in any available factory facilities may usually be feasible and economical. An especial advantage offered by jet-mill grinding in grinding of leguminous plants is that the jet-mill grinder does not cause a dramatic temperature rise such as that which is ~typical in other types of fine grinding mill. Such a rise would lead the thermal denaturation of proteins detrimental to the dietary quality.
According to observations made in pilot trials or in wheat grinding, also the dispersion of starch is not as significant in jet-mill grinding than in so-called pin mill grinding. In terms of successful pea fractionation and in the quality of obtained products, this may be particularly significant in a pea grinding process since the granules of pea starch are known to be more susceptible to dispersion than the granules of wheat starch.
From jet grinder 8, the ground product is carried along a tube 11 to an air classifier 12.
The extra pressure energy produced in jet-milled grinder 8 may be useful in this material transfer and in the air classification. The coarse fraction is returned from air classifier 12 along ~a tube 13 back to jet-mill grinding. The fine fraction is carried along a tube 14 into a cyclone separator 15, , ~
the coarse fraction obtained thereErom being ~ delivered to an array of raw material hoppers 17 for feed production. The~fine fraction is passed through a filter 16 ~also ~to feed~production raw material hoppers 17~. Both the coarse and Eine fractions may be carried by means o~ either a mechanical or a pneumatic conveyor. Such a direct dry separation is economically preferable and more "
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simple than generally extraction-based wet separation processes which usually require also the expensive drying of the products. After a successful fine grinding of peas, the air classification can also be effected by means of various prior known systems. To the right of dash-and~dot line 20 is shown a continuance of a conventional feed-production process, wherein the raw materials are supplied from the array of hoppers 17 to scales 18. The feed-production process is not illustrated but it includes feed mills, mixers, granulating machines, crushers and feed hoppers.
The quality of a pea seed used as raw material has an effect on both the economy of production and on the quality and yield of the final products. This effect or impact is, indeed, of such a caliber that an enterprise directed to foodstuffs that was set up in Canada is known to have failed just because the effect of uneven quality o raw material was not taken into consideration. One embodiment of a method of the invention includes the feature that available raw material comes from the crop of a leguminous plant variety determined appropriate and developed through plant breeding efforts for this particular purpose. An example of a novel pea variety particularly suitable for the present process is the new field pea variety HO~I
~HJA51850).
The colour af the seed of HOVI is yellow, similarly to soya, and the thin hull is~nearly free Of harmful tannin. In addition, the HOVI (H3A51850) .
pea has comminuted in tests more readily than some other known pea varieties and, in view of separation, it has preferred gualitiesi such as the size distribution o granules, which contribute to the air separation of its protein and starch granules. This is apparent when comparing the 2o(~70~1 Tables 1 and 2 set out below.

Table 1 Prot. ¦ Weigh~ Prot.,¦ Weight¦ Prot.
¦ ¦ Hulls ¦ ~ ¦ % ¦ %
Varieties ~ ¦ thull)¦ ¦
1.: 1 1 1 1 ¦ Helka-pea ¦ 7,7 ¦ 24,5¦ 18,0¦ 50,1 ¦ 82,0¦ 18,6 ¦ Panu-pea ¦ 10,0 ¦ c. 20 ¦ 18,5 ¦ 49,0 ¦ 81,5¦ 15,5 ¦ HJA51850-pea ¦ 8,8 ¦ c. 20 ¦ 18,0¦ 52,0 ¦ 82,0 ¦ 14,7 ¦ Ukko-bean ¦ 12,0 ¦ 29~1 ¦ 22~5¦ 59,3¦ 77,5¦ 20,0 . .
Table 2 (particle distribution) : : :
:
¦ Fine fraction ¦~ Coarse fracti:on :¦
,um ~ m I

¦Helka ¦ 20,7¦. (6,2-43,1)~ 36,0~¦~ tl5,4-50,8) ¦
Panu ; ¦ 19,3:¦~ (6,2-43,1)~ 35~,5¦ (10,8-61,5) ¦
;¦ HJA51850 ¦ 12,3~¦: t3~1-4;3,1~ 32,7: ¦ ~18,5-52,3) ¦
¦ Ukko ¦ 14,3 ¦ (~6~ 7,7) :¦~ ~26,5 ¦ (~4,:6-46,2)¦

According to Table 1, the percentage of protein hulled HOVI (HJA-1850) pea is about 20% but, nevertheless, the fine fraction contains a relatively higher proportion of protein (52%) than the fine fraction of other pea varieties. The reason for this can be found from the particle size distribution shown in Table 2. The ine fraction of H3~-pea (HOVI) contains relatively a larger amount of small particles than the fine fraction of other pea varieties. On the other hand, the particle size of the coarse fraction of HOVI (HJA51850) pea is more distinctively concentrated in a particular size range than that of other pea varieties. Especially, the lower limit 18.5 ~m of the coarse fraction variation range is clearly higher than for other varieties. For the sake of comparison, Tables 1 and

2 also illustrate test results for Ukko-field bean when grinding and air classification were conducted with the same parameters. The moisture contents of all varieties were 8.5 - 9%. The higher protein content (29.1%) of Ukko-field bean correlates positively with the protein content of fine fraction.
Apart from the selection of a leguminous plant variety, the degree of grinding has a decisive effect on the protein content of fine fraction obtained in air classification. The final grinding process is preferably capable of reaching the particle size of less than 20 ~m, whereby the cellular texture is sufficiently crumbled and the granules of various sizes are separable in dry state from each other by~means of air classification.
~ The pea meal f~ractions~proauced at a eed-producing plant by means of a me~hod of the invention are dietetlcally valuable novel products.
The economic protein content o~ fine fraction may be e.g. 35-55% depending upon apparatus settings and pea protein demand. The protein content of coarse fraction can be accordingly 10-15%. When the invention is integrated in a factory feed processing operation there is a beneficial use for all product fractions in various mi~ed feeds. Thus, lower protein fractions may be used as balancers in various feeds. Thus, the process may be advantageous both in terms of quality and economics.
The grinding and air classification may possibly be effected advantageously as a single work operation without one or more recycling opsrations of the coarse fraction as it is not necessary to ma~lmize the protein in the product. On the other hand, when using an embodiment of the process of the invention, it may sometimes be desirable to maximize protein content, and, when this is so it may be achieved, or example, by recycling. Thus, whenever there is a demand on the market and customers are prepared to meet the extra production costs, protein content may be maximized.
The most significant users of pea saed in ood industry include frozen and canned food industry as well as pea soup industry, none of which involves the use of pea in the form of flour or meal. However, the special functional qualities of both pea protein and pea starch have drawn increasing interest as a sub~ect of research in both food and technochemical fields e.g. in Canada, Denmark and France. Although a production method suitable for a feed-producing~f2ctorY is not known, it is said that bean meal has~been used as a raw material for pet feeds in France. According to the Canadian POS-Research Institute in Saskatoon, the air-classified pea meal fractions having highest protein contents are in their feed qualities much .

Z~07~31 like soya isolates and are obviously to some extent suitable for use e.g. as ingredients in pet feeds and in milk replacers for piglets. The proteinaceous fine pea fractions, i.e. pea protein feeds, have not been used at feed factories for the production of any type of mass feeds. A typical feature in a process of the invention is explicitly that the feed-producing factory itself is capable of economically using all resulting fractions in its productions, so there will be no waste products to be transferred elsewhere. For example, the proteinaceous fine faction is highly suitable for use in mixed feeds together with cereal meal and rape seed meal. The amino acids of grain, rape seed meal and pea supplement each other to provide a dietetically recommendable combination oE amino acids. In general, it can be said that pea protein can be used for replacing soya protein in various mixed feeds.
Thus, the pea protein feeds produced by a method of the invention provide a totally novel product which is not identified e.g. in the table "Feed tables and dietary standards" issued by the Agricultural Board of Finnish Government. This table reports that pea feed has a raw protein content of 22.5%, horse b~ean has 26.0%~and soya bean has~6.0%.~ Other leguminous;~plant products are not included in the table. Depending;on the setting of ; fractionation, the protein content of the novel pea protein feed can be adjusted ~to be~35~- 55~, also with horse bean more than 60~. In the concentrated from, this novel pea protein feed can be made to contain also most the fats, trace elements and mineral substances as well as sugars contained in , pea seed.
Unlike the pr~ior known studies, the cell ::

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wall fibres of pea are fractionated mostly into a coarse, i.e. starch fraction when using jet-mill grinding and, thus, jet-mill grinding is a preferred method in view of product quality if compared to conventional pin mill and turbo-rotor mill methods.
A pea protein feed production apparatus of the invention may also be provided with means for measuring the composition of fractions coming from air separation e.g. at fixed intervals by means of samples picked up from a continuous flow of product for controlling the production and adjusting the process settings on the basis of monitored results.
The measuring, e.g. determination of protein content, can be effected at a sufficient speed e.g.
by the application of available NIR-measuring technology. `An optical measurement of the relative abundance o starches from various air separation fractions can also be realized. Thus, by adjusting the settings of air separation equipment it is possible to have an affect on the quality and respectively quantity distribution of the fractions being produced.
A process of the invention for fractionatin~ the seeds of leguminous plants at a feed-production factory may also be advantageous in view of the food self~security and o the ability of domestic agri-businesses to withstand~ a possible c~isis in countries like Finland, which are de~pendent on the import~of supplementary~protein feed (soya, fish meal, feed yeasts) from abroad.
~The novel process offers better possibilities than before of effectively using the~seeds of domestic leguminous plants as a supplementary protein feed e.g. instead of imported proteins.

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Claims (13)

1. A method of mixed feed production involving the use of proteinaceous meal, including the steps of hulling and finely grading the seed of an edible leguminous plant to a flour, separating the resulting flour into at least a coarser fraction containing a substantial proportion of starch granules originating from cotyledon cells of the seed, and a finer fraction containing a substantially proportion of the protein from the seed, and incorporating at least one of said fractions into mixed feed.

2. A method as set forth in claim 1 in which the seed is pea seed.

3. A method as claimed in claim 1 in which the seed is field pea seed.

4. A method as claimed in claim 1 in which the seed is HOVI (HJA-51850) pea seed.

5. A method as set forth in claim 1, characterized in that the grinding is effected by jet-milling to provide a finer fraction having a particle size less than 20 µm.

6. A method as set forth in claim 1, characterized in that the air separated finer fraction has a protein content of at least 35% and, is passed into the mixed feed together with a grain and/or rape seed based raw material.

7. A method as set forth in claim 1, characterized in that the grinding is effected by jet-mill grinding to provide the seed with kinetic energy through the intermediary of a working gas and the grinding proceeds collisions between particles and/or collisions between particles and a wall and/or attrition between particles and/or attrition between particles and a wall.

8. A method as set forth in claim 1, characterized in that the jets of particles are caused to collide with each other by means of compressed air used as a working gas.

9. In mixed feed production processing equipment, an apparatus for processing seeds of leguminous plants, said apparatus comprising a hulling device for hulling seed, a crusher for crushing hulled seed, at least one grinder for grinding crushed seed to a ground product, and an air separator for separating the resulting product ground into at least a coarser fraction including a substantial proportion of starch granules and a finer fraction including a substantial proportion of the protein particles.

10. An apparatus as set forth in claim 1, characterized in that the grinder is used downstream of crusher comprises a jet grinder, wherein the jets of particles are caused to collide with each other or with a wall at a kinetic energy which is sufficient for crushing the cell walls open as a result of collisions between particles or between particles and a wall.

11. A feed meal or flour comprising a proteinaceous fraction of an edible pea seed meal or flour containing at least 35% pea protein.

12. A feed meal or flour comprising a proteinaceous fraction of an edible pea seed meal or flour containing 35% to 55% pea protein.

13. A mixed feed comprising cereal meal, rape-seed meal and a proteinaceous fraction of an edible pea seed meal containing from 35% to 55% pea protein.

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