FI74220C - FOERFARANDE OCH ANORDNING FOER SKALNING AV KORN. - Google Patents

Description

1 74220

Method and apparatus for peeling barley grains. - Förfarande och anordning för skalning av Korn.

Barley is an important crop in northern and cool growing zones. Its cultivation volume has increased sharply in recent decades, and especially in the last ten years, while the total yield of wheat and rye from traditional bread grains in Finland has clearly decreased. Barley is mainly used as feed grain. Traditional notions of the poor suitability of barley for food use and the lack of development of suitable industrial processes limit the use of barley as a food grain. However, barley is a very useful food raw material. The only problem is the separation and recovery of the usable parts of the grain.

A common and traditional way of using barley as feed is to grind it whole, and to feed the flour to the animals usually mixed with some other feed. The industrial peeling of barley used as fodder, for example for the purpose of increasing the value of fodder, is not known, and as such there are probably no economic conditions for it.

Plant breeding establishments have long had the goal of developing the so-called barley varieties without skin. So far, no economically viable variety has been developed. Plant breeding facilities are also working to develop many other properties that improve the quality of barley. For example, international work has been done to improve the lysine content of barley for several decades. However, lysine sacrifice has no economic significance as protein sources.

In Denmark, small-scale feeding experiments have been performed on rats using barley hulls as feed. Peeling was performed so that all the ingredients in the acana fraction (= light + shell + surface protein layer) were fed as broth to the animals. Despite the relatively high protein content of the bran feed, the growth results were relatively poor. The reason was the excessive fiber content of the barley bran feed.

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Barley has long been peeled into barley groats for food. A few thousand tonnes of these barley mills are also produced in Finland every year. Peeling is generally associated with a grain-breaking rough-cutting treatment. In practice, barley germ processes become so little bran that its special further processing is not profitable. Bark bran from the manufacture of grits is usually delivered as such as a waste product to other barley feed flour.

The most significant food user of barley is the malt industry.

However, its processes do not involve barley peeling. Most of the international food research on barley is related to the malting industry. Thus, it is understandable that very little research has been done on the peeling of barley and the properties of the hull flour.

The husking treatment of barley to date has been limited to the removal of surface fibers and the grain has been crushed, cut or crushed so that its husk, with the exception of surface fibers, and the kernel parts are mixed together.

In none of the peeling methods used and known has the valuable surface layers of barley grain been separated into fractions for industrial utilization.

The separation and recovery of usable parts of barley in connection with and with the aid of barley peeling has not been previously carried out, studied or proposed. In all peeling methods used, the valuable layers below the peel have remained or mixed in relatively low concentrations in the peel and / or peeled product.

A barley grain is a single-seeded unopened fruit. It arises from the fetus of a single barley flower. Other parts of the flower are also involved in the production of the fruit, or grain. In the barley grain, the fruit peel and seed coat surround the aleurone cell (surface protein), the starch endosperm (barley core), and the embryo. Outermost are 3,74220 easy. A schematic sectional view of the structure of a barley grain is shown in Appendix Figure 1. The following structural parts are distinguished in a barley grain: 1 the starting point is the well-known property of barley in botany that the most nutritionally valuable constituents of the grain are in the surface layers of the grain or relatively close to the surface of the grain. On an industrial scale, a profitable method for producing flour made from valuable nutrient surface portions of barley grains was realized due to the fact that the barley kernel remaining in the production of flour by the method of the invention is as such a useful raw material for a large barley starch industry. An example of this is Oy Alko Ab's barley distillery to be built in Koskenkorva. In connection with this, about 150,000 tons of barley will be processed annually. Such a mass allows for special industrial peeling. Surprisingly, it has also been found that Oy Alko Ab's own process would benefit significantly if the barley starch raw material used in the process is treated before the starch ethanol process with a method that removes the aleurone layer surrounding the starch core as accurately as possible.

The object of the invention is therefore to provide a method and apparatus for producing special flours, i.e. surface flours, from valuable surface parts of a barley grain, while the remaining barley kernel is better suited as a raw material for the barley starch industry.

This object is achieved by a method according to the invention 4 74220 in which, as a starting point known per se, the flake layer and a part of the shell layer are removed by dry grinding and the peeling fraction thus formed is separated and recovered separately. What is new in the invention is that after separating said first peeling fraction, dry grinding is continued until at least part of the aleurone layer, i.e. about 10-30% of the total weight of the grains, is removed, and the aleurone layer-containing surface flour and remaining barley kernels are each recovered.

The separation of the peeling fractions is carried out in such a way that they are recovered separately directly at the various stages of peeling. Thus, the need for screening can be substantially reduced.

The completion of the dry grinding can be determined by measuring or monitoring the material composition of the surface flour and / or the barley kernels to be ground. The measurement, e.g. the determination of the protein content, can be performed sufficiently quickly e.g. using known NIR measurement techniques.

The invention also relates to an apparatus for carrying out the method and the features of the apparatus are set out in the appended claim 10. It is important for the implementation of the apparatus that in the first dry grinding stage the Of course, if desired, receiving means for several grinding fractions can also be provided.

Abrasive type abrasive devices have previously been used primarily in rice husking, and similar types of devices can also be applied in the present invention.

The peeling result naturally also depends on the properties of the barley to be peeled, e.g. shell thickness and hardness. The thickness and hardness of the barley 5 74220 husk layer (light, pericarp and test) vary significantly depending on the variety and year of harvest. For this reason, the method involves and is essential for the peeling result that for the barley peeling according to the invention the quality of the barley batches is determined by analyzes and each barley batch is directed to the peeling line according to the quality of the grain batch. quality barley.

Based on the analysis, a peel-facilitating pretreatment can also be performed, such as a mild steam treatment which does not moisten the grain but mainly causes the peel to come off more easily by minimizing the aleurone layer material in the grinding step.

The barley surface flour produced by the method according to the invention is thus a completely new product. The protein content of normal barley flour ground from whole grains is 10.5 to 12.0% of the dry matter. The new surface flour product has a protein content of 16.0 to 19.0% of the dry matter. This new surface flour gives in concentrated form the most valuable so-called barley in the aleurone layer. functional protein. It is made up mainly of proteins called albumin and globulin. It is known that these proteins of barley surfaces are rich in so-called essential amino acids such as lysine and methionine, which are generally scarce in cereal products. The barley kernels, on the other hand, have the so-called storage proteins such as hordeins and glutelins, which are not considered as nutritionally good as albumins and globulins.

The Department of Animal Science of the University of Helsinki has an acting Assistant Professor Matti Näsi has studied the properties of feed ranks from the ethanol process as a waste product. In a normal ethanol process, the amino acids originally present in the grain are largely destroyed or coaculated into a form unusable for the animals. This is due in part to the process itself e.g. the temperatures required for evaporation and the high temperatures used for the final drying of the 6 74220 waste products which become part of the fodder. For example, the destruction of lysine in the normal ethanol-lipocess process has been clearly observed.

By the method according to the invention, these amino acids are recovered before the processes using starch, and thus a large part of the amino acids of barley are introduced into the nutrient chain in an indestructible and concentrated form.

Barley and wheat grains have a fat content of 2-3 percent and oats about 6 percent. Almost all of the barley grain fat is concentrated in the germ and aleurone layer. Barley fat is mainly formed by the so-called. unsaturated fatty acids. A total of 15 fatty acids have been found in barley (Eriksson et al. 1972). The fat of barley, like all cereals, is entirely oily. Barley fat is rich in linoleic and linolenic acid, which are considered to be of particular nutritional value. Some of the fatty acids are known to be transferred as such to tissue fats and milk, for example. Thus, a good fat composition in food is beneficial to humans and in feed it directly affects the quality of livestock products.

It is known from barley grain that the fatty acids in the surface parts are more unsaturated than the fatty acids in the inner parts. In addition, barley fats are known to be concentrated in the embryo and aleurone layer. With the method according to the present invention, barley fats are recovered in a new product, the surface of a flour, the fat content of which increases to 4.5 to 8%, depending on the type of flour. When the fats are located in the surface layers of the grain and in the germ, by the method according to the invention they can be removed from the industrial raw material using the barley starch part for utilization on an industrial scale. In the peeling tests carried out during the development of the method, more than 80% of the grain fats have been included in the peeling fraction. The fats are practically left in the surface flour. The fat content of the mites is only 1%.

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In the analysis of a barley grain, the ash content is reported as 2.5 to 3 percent, and this indicates the amount of minerals contained in the grain. Barley grain minerals are concentrated in the aleurone layer (61 percent), germ (12 percent), and husk (7 percent). The remaining about 20 percent of the minerals are in the inside of the grain. The most valuable magnesium, phosphorus and potassium as well as zinc are mainly in the surface parts of the grain and are included in the surface flour fraction.

Most of the vitamins in barley are also left in the surface flour. Barley contains more vitamin E, niacin and folic acid than oats and wheat. Otherwise, the vitamin level in cereals is the same. Vitamins are concentrated in the embryo and aleurone layer (Eriksson et al. 1972). In the method according to the present invention, it is precisely these parts that are taken into the surface flour. In hitherto known further processes using starch, such as in the production of ethanol, the process temperatures rise so high that the vitamins are also largely destroyed.

Dry peeling of barley used to make starch reduces environmental problems and the need for drying, as well as the need for further process capacity. The aim of industrial processes (starch modifiers, ethanol and isomeroses) using cereal starch as a raw material is to get the starch out of the basic process as pure as possible. In other words, the starch must be separated from other cereal ingredients such as proteins, fats and fibers. It is therefore characteristic of cereal starch processes that the separation of protein from starch forms a considerable part of the whole process, and also of the processing costs.

In addition to fibers and fats, cereal grains also contain proteins in a predominantly water-insoluble form. Thus, cereal proteins, like the root starch industry (potato and tapioca), could not be obtained with fruit water directly by washing away the starch. In known processes for the production of barley starch (eg Finnish Nestesokeri Oy's Finnish patent 8,74220 772260), barley is ground in its entirety, usually dissolved or wet. Most of this wet whole grain crumb is then separated from the husks, embryos, protein and other material by screening so that a starch-rich fraction remains for further processing. In known cereal starch processes, it has hitherto been assumed that protein and other non-fibrous grains cannot be separated from starch by the dry method or at least without high loss of grain starch core. Therefore, cereal starch processes generally use a lot of water. In practice, the dry grain pulps to be ground are completely soaked in water for separation, and virtually all of these pulps then have to be dried again.

The water-binding capacity of barley husk and fibrous husk parts is known to be very high. According to studies, 1,000 kilos of barley husks bind about 2,000 kilos of water when irrigated. Water itself is cheap, but removing water from products that must be done by evaporation into water vapor is expensive. In addition, abundant waters also easily become environmental problems in the grain starch industry.

According to the present invention, the non-starchy portion under the husk is peeled dry out of the grains more accurately and more than usual. This completely avoids the usual need for irrigation in this part. This procedure is possible and meaningful on an industrial scale and will be profitable in integration with the rest of the barley grain starch kernel industry. Thanks to the method according to the invention, considerable sums can already be saved in drying costs.

The method according to the present invention is also a new method for improving the overall economy for the production of an economically advantageous and hitherto known starch core (barley kernel meal) for the integrating industry. The transition from the normal method to, for example, 20% to 9,74220 cent peeling reduces the sizing requirements of the starch process equipment by up to 50%. This is based on the fact that both the amount of water and the amount of by-products to be removed are decisively reduced due to the abundant "pre-peeling". This reduction in the sizing requirement of the further process is a valuable additional advantage of the method according to the invention as a by-product.

A further advantage of the invention is that the barley starch kernel peeled by the method according to the invention, when ground, is better suited than hitherto known barley flour for industrial baking, for example as an economically advantageous flour supplementing wheat. The hitherto known and commonly used method of making barley flour is that the grains have been peeled or crushed so much that light and part of the peel layer has been removed. Much of the aleurone layer of the grains is usually left in the barley flour, as it has always been desirable to avoid grain loss. It is known that barley flour has been widely used in home baking to make barley pancakes. In contrast, in industrial bakeries, barley flour is known to be agglomerated, rancid, and poorly preserved. This is mainly due to the fat that enters the flour with the barley aleurone layer. In the preparation of the new method, the fat is removed from the core flours used for industrial baking, while the nutrient-rich surface flour fraction is obtained for other uses.

The method for peeling barley according to the present invention is also important for the crisis-resilience of food supply in barley-intensive countries such as Finland. The new method will make it much better possible to use barley on a large scale as food.

In the following, the method and apparatus according to the invention will be illustrated with reference to the accompanying drawings, in which Figure 1 shows a cross-section of barley grain and Figure 7 shows an increase in cross-sectional area taken from point II of Figure 1, showing the barley grain layer structure in more detail.

Figure 3 shows in vertical section a schematic diagram of a husking device known for husking rice and which can be applied in the method and device according to the invention.

Fig. 4 shows a general block diagram of an apparatus implementing the method according to the invention, and Fig. 5 shows the dependence between peeling time and peeling degree in two different experiments with two different barley varieties.

Thus, the peeling is carried out by smooth surface grinding using a peeling device according to Fig. 3, comprising a grain feed channel 1, a grinding stone type grinding device 2 with grinding stones attached to a rotatable vertical axis, a cylindrical metal mesh 3 thus, the degree of peeling can be controlled. Air is sucked from the device as indicated by the arrows A, whereby the replacement air is led from the holes in the grinding stones and exits through the metal mesh 3, taking with it the surface flour fraction which comes off during grinding. The device can also be built to operate horizontally.

At the beginning of the grinding, the light and a part of the shell layer come off (cf. Fig. 2). This flake and shell fraction is best collected separately so that it does not enter the surface flour fraction to be recovered later. In practice, these are such thin layers that part of the shell layer inevitably enters the surface flour fraction containing the aleurone layer, which is later recovered. However, if necessary, the shell parts can be removed from this surface flour fraction by screening 74220 based on their physical properties. When the quality of the barley is known from the preliminary analysis and the grains are sized, the recovery steps of the different fractions can be determined quite accurately on the basis of the peeling time, as can be seen in Figure 5. Achieving the same degree of peeling with a lean grain (Experiment I) requires a slightly longer time than with a lumpy grain (Experiment II). A uniform peeling result therefore requires that the grains to be peeled be as homogeneous as possible. The requirement for the homogeneity of the grains can be realized by determining the quality of the barley batches by rapid analyzes and by placing substantially different batches of barley in different receiving silos 5 (Figure 4). In this connection, pre-treatment can also be carried out on thicker and harder barley husks to facilitate peeling, e.g. As a second measure to meet the homogeneity requirement, the grains can be classified into 2-3 classes based on grain size or bulk density before peeling. In Fig. 4, reference numeral 6 denotes a classification unit from which different grains are led to intermediate tanks 7 of different peeling lines A and B. From the tank 7, grains are fed by a feeder 8 to a first peeling unit 9 with a peeling device according to Fig. 3. The peeling device of this peeling unit 9 is adjusted so that the grains remain in this unit for a sufficient time to remove the light and part of the peeling layer. Reference numeral 11 denotes this first leaving fraction, which can be used e.g. as fuel.

Thus, the "pre-peeled" grains are fed to a second peeling unit 10, which also has a peeling device operating according to the principle of Fig. 3. In unit 10, peeling is continued until the aleuron layer (Figure 2) is partially or completely removed.

pintajauhofraktio thus formed are recovered by the arrow 12. If necessary, screening is carried out with a sieve 17, whereby the crust 19 involved in the flour fraction is separated and the pure flour 18 74220 containing the aleurone layer is recovered.

After peeling in the second peeling unit 10, the starch-containing core part 16 of the barley remains, which can be supplied to the starch-using industry whole, crushed or otherwise processed into a suitable shape, depending on the the special need for a follow-up process.

The degree of grinding, i.e. the residence time of the grains in the peeling unit 10, is controlled by feedback loops 13, 14 and 15, which include a fast-acting e.g. NIR analyzer 13 which monitors or measures the composition of surface flour and / or starch cores (large grains) leaving the peeling unit 10, e.g. When the actual aleurone layer has been ground off and the grinding is applied to the aleurone zone of the starch endosperm (Fig. 2), e.g. the protein content of the large grains clearly decreases and the starch content of the surface flour increases rapidly. Depending on the measurement results, the control unit 14 provides the necessary feedback control 15 to the controller 4 of the unit 10.

Although the peeling units 9 and 10 connected in series correspond in principle to each other, they may differ from each other in technical details. Such details include, for example, the roughness of the surface of the grinding stone, the mesh size of the metal mesh, the thickness and height of the ring space between the grinding surface and the metal mesh, etc.

There can be more than two peeling units connected in series. The method according to the invention can also be implemented with one peeling unit by running for different settings several times in succession. That is, the different peeling steps are performed with the same grinder by passing each grinding batch through the grinder at least twice.

Peeling in the peeling units takes place as a continuous process, in which mainly the flow rate through the peeling unit determines the degree of peeling. The degree of peeling is also affected by the degree of filling of the peeling device. The feedback control 20 from the control unit 14 to the feeder 8 and the first peeling unit 9 ensures that the flow into the peeling line is equal to the flow leaving it and also follows any variations in the amount of discharge flow due to adjusting the degree of peeling. In this case, no substantial intermediate storage is required between units 9 and 10. For units 9 and 10, batch feeds can also be used.

With the aid of the above-mentioned adjustable grinding degree and, if necessary, screening, a new surface flour product is separated from the incoming barley by the method according to the invention, which has e.g. protein 16 to 19% of dry matter. The aleurone layer of barley is included relatively accurately in this surface flour. Surface protein layers are always present in the barley grain because they are formed already in the early stages of growth. With the method and apparatus of the invention, this surface protein layer, or at least most of it, can be removed by peeling off the surface of the grain when about 10 to 30 percent of the total weight of barley is peeled off. With the method according to the invention, it is also possible to easily separate low-value lignin-containing light and at least part of the shell layer by simply recovering them directly directly at the various stages of peeling. The amount of these is 6-9% of the total weight of the grain, depending on the barley. After separation of the flake and husk fractions, the actual product remains surface flour, which is 3-23% of the total weight of the barley, depending on the degree of husking. These surface flours can be marketed either as a single product or can be fractionated into several surface flour granules with different properties.

Claims (13)

A process for peeling barley grain in which the bait layer and a portion of the peel layer are removed by dry grinding and the thus formed peel fraction is separated and recovered separately, characterized in that, after separation of said first peel fraction, the dry grinding is continued until eat at least part of the alu layer, or approx. 10-30 of the total weight of the barley, removed and the thus formed, alueron layer containing the surface flour and the remaining barley cores are separately collected separately. Process according to claim 1, characterized in that the scaling fractions are separated from each other by collecting separately separately during the different scaling stages. Method according to claim 1 or 2, characterized in that the completion of the dry grinding is determined by measuring or observing the composition of the cores and / or grinding fractions during grinding. 4. A method according to claim 2, characterized in that in the first dry grinding stage the bait and shell layer fraction is separated and in the second dry grinding stage the alu- rone layers containing the surface flour are separated and collected separately. Process according to claim 4, characterized in that the different scaling stages are performed with different grinding devices. Method according to claim 4, characterized in that the different scaling stages are carried out with the same grinding device by conducting the respective batch to be scaled at least two. passes through the grinding device. 7. A method as claimed in claim 4, wherein in the second dry-grinding stage the collected flour is screened to separate in these still occurring shells from the surface flour. 8. A method according to claim 1 or 2, characterized in that prior to the scaling the grits are sorted on the basis of their size, shape or other such properties and are controlled for scaling to different scaling lines. 9. A method according to claim 8, characterized in that the sorting is carried out by clarifying the quality of the grain batches by analyzes, that on the basis of analysis is carried out when a scaling facilitates pretreatment such as a mild meadow treatment and the grain is controlled by a mechanical grit size sorting. different scaling lines. Apparatus for carrying out a method according to claims 1-3, to which the device comprises a grain feed duct (1), a grinding device (2) of the grindstone type, in which the grindstones are attached to a rotatable shaft, air ducts for conducting air substantially radially through the grinding zone and a regulator (4), by which the holding time of the grain and thus the degree of scaling can be controlled, it can be noted that the device additionally includes first means for receiving the first grinding fraction (11) and second means for receiving the grinding zone. the second grinding fraction (12). Device according to claim 10, characterized in that the means (13) for observing the degree of grinding are arranged with a feedback control (14, 15) to control said regulator (4). Device according to claim 10, characterized in that the device comprises a first scaling unit (9) if