Flaking of wheat quality grinding technology

Technical Director of Ltd OLIS, Ph.D. Vereshchynsky A.P.

«Grain storage and processing» № 9, 2008.
Task of improving the quality and yield of flour remain valid for the majority of mills grinding wheat cultivar that requires a search for secure and economically viable solutions. One of the directions of this search is to use the processing of grain on the stages of its preparation for the meal, known abroad under the term «debraning». Debranning - derived from the word «bran» (bran), which can be translated as scales, respectively, a car, to implement the process scaling,  peeler, called «debraner» (debranner).

          Remove from wheat shell, then grind it - the idea is not new, and even, at first glance, is not devoid of logic. As you know, in the process of peeling from the surface of the grain is removed much of the shells, dust particles, microorganisms, and grain weight itself further purified from the majority of it contains impurities. Thus, the grain of wheat must acquire higher milling characteristics, which, in turn, should favorably affect the outcome of grinding, especially high-grade.

          However, grain, subjected to flaking, very different from the original grain physico-mechanical, biochemical, physiological and other properties. It is obvious that the use of peeling most of the processes in the structure of grinding beyond the traditionally studied and applied laws. Thus, the possibility of practical use of simple, at first glance, the idea calls for the development of new technology and hardware.

             In domestic millers most significant in this direction is the study I.T. Merck, I.R. Dudareva, held in OTIPP (Odessa), as well as work B.M. Maksymchuk, G.A. Yegorova, and other researchers conducted in VNIIZe and MTIPPe (Moscow). As a result, we studied changes in the properties of grain in the process of preparing wheat for milling by peeling, suggesting possible ways of implementing this process, and also described the positive effect obtained by the experimental grinding.

             There are details on the work in this direction and abroad. For example, in the article "Determination of ash - a useful standard, or a waste of time?" Researchers from the UK, the Netherlands and Australia, reveal the mechanism of increase of white flour that is obtained by removal before milling "of the upper layer of bran. It is noted that as a result of this treatment improves and baking properties of flour, in particular, its ability to forming the dough.

            The new technology of disinfection of grain offered recently by Buhler, involves cleaning the surface of wheat peeling. In particular, notes that after this treatment, flour is obtained with higher brightness, it decreases the number of particles of shells and improves its appearance.

             Debranning as the new technology of grinding machines for its implementation, benefits, and the resulting positive effect are declared and in the materials the company PROKOP.

            However, in such a vast and well-developed industry, as domestic millers, no known cases of industrial applications under review, processing methods, neither national nor foreign developers. By our hypothesis, the reason for this is the lack of truly proven technology and means of implementation, allowing the effect of grinding is guaranteed to turn research into the economic impact on the industrial level.

             Nevertheless, after reviewing all the available results of the work associated with debranning, we thought it indicated the direction quite promising in terms of practical use. As a result, since 2000, started our own searches, research and implementation. Already the first experiments confirmed that in preparing the grain for milling processes at its peeling action is closely intertwined with the processes of conditioning. Hulled grain is much more intense and more evenly absorb moisture from its large increments. This effect is important to use for saving time and improving the quality of air conditioning. However, it was found that the effect of significant increase in white flour comes the separation of membranes for more than 5%, and in some cases 8% or even 10% of the weight of grain. When the extent of treatment will inevitably injure the fetus play a positive role in the processes of conditioning, and dampen the grain becomes vulnerable to caking. Thus, in view of the upcoming process of conditioning, surface treatment is necessary to carefully, but in very benign conditions. To solve this problem is best car brand MAO, we have developed as a more effective analog current hulling machines (Photo 1). The essence of design and features of its work detailed in the article entitled "Surface Treatment of grain mills, magazine storage and processing» № 5, 2005. As a result of interactions with tools, this machine separates the shells in the amount of 1,5-2,0% by weight of grain. Specified leads to a reduction in ash at 0,05-0,08%, increase in kind of 15-20g / l and a decrease in trash by 30-40%. These data show that the machine is really much more effective MAO traditionally used hulling machines such as BGO and A1-A1-LMC. In this case, the grain is practically not injured, and its surface acquires a rough surface. For a uniform moistening of the grain does not require a machine intensive moisturizing type A1-BSHM that energy-intensive and also hurt as the grain itself, and its nucleus. Sufficiently effective hydration can be arranged by spraying water even in the ordinary screw conveyor is several meters long, providing, if necessary, secure the increment of moisture content to 5-6%. Moreover, by increasing the rate of absorption of moisture, while conditioning may be reduced by 30%, which is especially important when processing a dry, glassy grains.

               Our observations show that the removal of the shells in large quantities is most advisable to carry out before the final stage of conditioning by providing two, but for the dry and vitreous grains - three phases in the case of applying the method of cold air conditioning. Attempts to use for this purpose known in the industry of hulling and grinding machines, including Various modifications of A1-ZSHN proved to be untenable. However, experience has allowed to formulate the basic requirements for the necessary machine. Such a machine should provide a high degree of uniformity and peeling treatment without the formation of denuded areas of the endosperm. The process of peeling must be carried out with low power consumption and to be stable for grain with moisture content up to 17%. In addition, the machine should be easily managed and customized to any scaling coefficients of the required limits, be reliable and integrated into ACS mill. Meet these requirements we have developed design of the machine under the name "Cascade" and its lineup, which includes four models with different performance. Approaches to the development of this vehicle, design features, and of the effects detailed in the article: "New machines for surface treatment of high-grain, magazine storage and processing» № 5, 2002. With regard to the shelling of wheat, as part of its preparation for the milling, processing of the Cascade reliably reduces the ash content of grain 0,2-0,3%, which is an order of magnitude higher than in the traditional lines of preparation of grain, equipped hulling, washing machines or wet-peeling machines. Analysis of the cut on the ash showed that the required degree of peeling of the value of their ash content corresponds approximately to the ash content of bran milling department. Indicated suggests that the separation of a significant part of the bran in the machines "Cascade" to the grinding of grain does not entail the loss of flour, affecting its output. The same conclusion, and lead test results on the starch content. When processing in the machines "Cascade" observed a further reduction of trash and the nature of grain growth. Electricity costs of processing depending on the degree of scaling up 9 - 15 kW / m. In the process of shelling corn is heated to a temperature of 30-35 degrees, its moisture content is reduced by 0,3-0,7%, mainly due to dry the shells. This decrease in grain moisture, it is necessary to compensate for the last stage of conditioning. Freed from the shells, warm corn as rapidly dries up, and, in the case of moisture, it absorbs moisture. Conditioning processes are accelerated, gaining signs of hot air-conditioning to the strengthening of weak gluten. At this stage Mills technologist a real opportunity to correct the mistakes and blunders committed by the previous stages of conditioning. Correctly using the effect of heat and mass transfer in the shelling of grain, its moisture and its interaction with suction air transport communications and possibly within the last phase of conditioning as dry grain by up to 1%, and moisten by up to 2% of the distribution of added moisture on the surface or deep into the grain .

             When grinding grain, prepared by the above way, the character in torn cereals formation process. For grinding grains requires far less energy, which fully compensates for the energy expended in the shelling. A clear demonstration of this is that the service rolls before the next cutting increases in 1,5-1,7 times. In scaling the grain integrity of membranes and their relation to the endosperm, so large  product is formed more by the combined assessment they are smaller, but better quality. Even at high mode grinding cereals formation limited, mainly the first two systems. Taking into account, that the specific content of the shells in the grain is low, and due to endosperm weakened to beg shell, in most cases, only one Roller system. In some cases, with satisfactory performance, in place of Roller system can use a system equipped with grinding machine and even with entoleytor. Options rolls in torn during the traditional recommended. However, experience has shown that, given the nature of the chops of fluting is desirable to reduce per unit on all systems. According to our observations, with the number and quality of large-dunst products, which provide the above-described process fragments, the use of enrichment on sieve-winnow machines is not the determining factor for obtaining high quality and yield of flour.

                 In the grinding process of grinding of large-dunst product is not distinctive features. However, in most cases, the opportunity to reduce the grinding process on a single system, due to the receipt of the torn of smaller products, presumably with a greater development of microcracks. In the case of threaded rollers, and (or) entoleytors to ensure high recovery on the products and grinding systems, significant deterioration in the quality of flour we have not seen. Guaranteed high recovery (60-70% for "head" of grinding systems) provide us used entoleytors type Simpaktor. Application of entoleytors this design is an additional argument in the decision to reduce the number (length) Roller Systems.

            Process fragments, the main features of which, the trends and means to implement given above, were united in our technology to commercial application. The use of such technology in various mills has its own characteristics. For example, for use in mills with low productivity, such as P6-AVM, MBC, as well as some models "Harkovchanka" we have developed a compact model setup, including a car "Cascade", the required performance with a set of necessary technology, transportation and other elements (Photo 2 ). Such plants are aggregated with the respective brands of mills and used to work back part of their regular pneumatic air. In some cases, the introduction of debranning requires some changes in the technological features of the grinding mills of these offices.

           Very common and popular in recent years are the mill capacity of 40 - 60 tons / day. Typically, this packaged imported mill or mills of domestic buildings, created by individual projects. A distinctive feature of these mills is condensed structure grinding is realized on the basis of industrial equipment. However, most of these plants can not withstand the professional critics in the observance of basic technology of grinding, line-up, construction and other decisions. Implementation ofdebranning in mills of this type are usually carried out as part of their renovations, or used in the construction of new plants (Fig. 3).

            Introduction of new technology on the mill types described above, consistently provides the following results. During the one-sorted grinding, usually get 69-71% of flour whiteness, 58-59ed. Two-sort regrinds conduct exit flour 57-65% (white 60., Ash content of 0,49-0,51%), and first grade flour (white 43-45ed., Ash content up to 0.72%) to total yield 73-74%. In this case, the flour is characterized by premium customer appeal (without any visible "inclusions" and Gray shades). When three-sort grinding, the total yield of flour is 74-75%, which provides a selection of 2-3% of flour second grade. Actual performance of mills increased by 20-25%, while electricity costs do not exceed 70 kW per ton of processed grain.

         The table shows the results of grinding at the mill capacity 100t/day, Reconstructed with the use of machines "Cascade". Besides the introduction to the preparation of grain debranning, substantial changes were made and the grinding department. By reducing the length of the two systems Roller line was reduced by 17%, and the released part of screening surface is aimed at reducing the value of the " unseeding " and as a result - turnover products. According to the results of reconstruction the total length of the line was 1200sm Roller. with a total area of screening surface 58.2 sq. m. Grinding department includes 4 torn, 2 screening, 2 and 4 grinding milling systems. Sanding and two grinding systems are implemented using the microroughness rolls. In turn, the grinding of the rollers are equipped with microroughness entoleytors. Enrichment of large-dunst products carried out in two double-hulled sieve-winnow machines. For additional beg shell particles, there are two grinding machine. It should be noted that in the table were obtained when processing grain, containing small fractions of up to 15%. In spite of this, these results, at least not inferior to the results of grinding mills at capacity of 250-300 tons per day. with a developed structure of the process, implemented complete equipment. In addition, the processing of tons of grain consumed 30% less electricity, and to establish the identity of production capacity is required in 1,5 times less investment in equipment and construction part.

               Summing up the grand total, we note that the introduction of technologies that are characteristic fragments of which are described above, in dozens of existing mills the very different capacity and equipment, as well as use in creating new industries, have confirmed its effectiveness and allow us to speak about the achievements of practical success.


Table. The results of the mill capacity of 100 tons per day.
ash content of the original grain,%
Ash content of grain on the 1 st torn system
The yield of flour / s%
White, ed. / Ash,%
The yield of flour 1 / c,%
White, ed. / Ash,%
The yield of flour, 2 /,%,
White, ed. / Ash,%
The total output of flour,%
Mass party, m
Average daily production, tons / day
Energy consumption per ton of grain, kW / m


Photo 1. Machine Design MAO.




Photo 2. Typical installation for debranninga the mill P6-AMS-15.



Photo 3. Node of debraning implemented machines "Cascade" in the mill capacity 60t/day



Photo 4. Node of debranning implemented machines "Cascade" in the mill capacity of 100 tons per day.