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PRE-MILLING GRAIN CLEANING PROCESS AND WHAT TO KNOW

13 September 201613 min reading

Wheat, which goes through various stages from harvesting to arriving at our tables, is subjected to several natural and unnatural contaminants which pose a risk to quality and human health. Elimination of all of these contaminants from the what before it is processed into flour and comes to the dinner table as a finished product is crucial.

kapak2Wheat is the raw material of bread, which is one of the fundamental nutrients for humans. Wheat, which goes through various stages from harvesting to arriving at our tables, is subjected to several natural and unnatural contaminants which pose a risk to quality and human health. Elimination of all of these contaminants from the what before it is processed into flour and comes to the dinner table as a finished product is crucial. The cleaning and sorting technologies available in mills today successfully handle these cleaning processes.

How many different stages are involved in the grain cleaning process? What kind of technologies are used in these stages? What are the highlights of selection and use of these technologies? Why is an effective cleaning of grain important and what are the effects of this process on quality or other factors? We pose all these questions and more to the leading manufacturers of technology solutions in the industry. İmaş Machinery Industry Corp. Mustafa ÖZDEMİR, the General Manager, Hüsamettin Ali ÇAĞLAR, Assistant General Manager at Genç Değirmen Corp., and Mustafa KÖROĞLU, Process Manager at Alapala Makina answered our questions.

CLEANING AND SORTING IN MILLING In milling industry, what are the cleaning and sorting stages used in pre-milling?

Mustafa ÖZDEMİR - İmaş Makine Sanayi A.Ş At İmaş, we consider all operation issued from an academic and practical perspective, and deal with them within the context of R&D. First of all, we need to understand the term “storage” and the concept of “cleaning” which is used in milling business. For us, a cleaning process includes the separation of foreign substances from a granular product and elimination of contaminants from the grains.

When talking about sorting and contamination, all physical, chemical and biological factors should be considered. The materials which are defined as “nonmillable foreign substance” should be cleaned from the grain. In flour or semolina milling, the wheat goes through a triple-stage cleaning process before milling. Rough and detailed cleaning is done during these stages. Rough cleaning is sorting of targeted grains from the material by use of various methods. Detailed cleaning is elimination from the grains to be milled of all excesses and contaminants which should not pass and reach the milling product. Rough cleaning begins when the product enters the mill. Dominant detailed cleaning is done before milling and then the grain is delivered to milling. In flour and semolina milling, these stages are referred to as POST, MAIN and FINAL cleaning.

Hüsamettin Ali ÇAĞLAR - Genç Değirmen A.Ş. In order to obtain a good quality of flour, wheat should be stored free of foreign substances and tainted wheat prior to milling. 5 principles can be used to eliminate these foreign substances and tainted wheat. These are sorting by size, sorting by specific weight, sorting by air resistance, sorting by natural characteristics and sorting by shape.

Sorting by size: It is the sieving/sorting method which is one of the easiest cleaning principles so far. Substances that are smaller or larger than wheat are sortd by revolving, shaking and reciprocating motions. In this stage, machinery such as drum filters and waste purifiers are used.

Sorting by specific weight: Some of the contamination may have the same size as wheat and cannot be eliminated by sorting by size. Such sorting can be achieved by using vibration and adjustable air stream. Some machinery which can ensure multiple sorting have been developed in the recent years. Machinery which can handle sorting by specific weight are destoners, light grain separators, concentrators, and combined machinery is the combinator.

Sorting by air resistance: This process helps to clean materials that are lighter than wheat as well as other waste such as dust, sand and fodder. Wheat is cleaned from said contaminants by using equipment such as air channels and radial harrows with the aid of ventilation hoods.

Sorting by natural characteristics: While natural characteristics refer to metal contamination, it has come to include colours in the recent years. There are various magnets to prevent metal contamination. Such as drum magnets, cascade magnets, rod magnets and electromagnets... Elimination of metals from the process is important as it may damage the machinery and pose a risk of dust explosion. In sorting by colour, it is not possible to sort different shades of one colour. This is achieved by using electronic eyes and pneumatic air jets.

Sorting by shape: When the size and specific weight of waste materials is the same as wheat, sorting by shape can be used. This is achieved by using disc, spiral and cylinder separators. This process has become more efficient in the recent years, particularly by using high-capacity trieurs.

Mustafa KÖROĞLU - Alapala Makina The waste eliminated from wheat respectively are as follows: Metals (with magnets), fodder, large soil and stones (with waste purifier and harrow), small stones, small soil and fodder that could not be eliminated in waste purifier (in destoners), waste materials which stick to wheat scab and cannot be completely separated from wheat (in debarkers) are eliminated from wheat and the waste is separated.

DRY CLEANING AND WASHING METHOD How can you clean and separate foreign substances and agricultural pesticides from wheat in the most efficient way? How successful is the dry cleaning method, which is the most common method today, when compared to washing?

Mustafa ÖZDEMİR It is known that washing is the most effective way cleaning wheat of contaminants including foreign substances, pesticides and nuclear fallout. Washing is also reported to be the most effective method in sorting, elimination of contaminants and supply of tempering water. However, due to environmental concerns and high costs, we recommend using dry cleaning where it is not a must to use washing, such as to eliminate excessive contamination. This is because a dry cleaning unit that has been equipped with an effective cleaning mechanization, diagram and “sorting-cleaning efficiency” can produce good results with less damage to the environment and lower costs. Wet cleaning systems can be recommended to small businesses which do not cause environmental problems and in regions where water resources are plenty and wheat is over-contaminated.

Hüsamettin Ali ÇAĞLAR Debarking and peeling processes have been effective in reducing the effects of agricultural pesticides. A debarker should be used during the tempering process of the wheat. Dry cleaning method has achieved the same success as the washing method thanks to the developing technology and machinery. Furthermore, dry cleaning has replaced washing as a more common method, due to concerns of waste water and environmental pollution. Mustafa KÖROĞLU It is very brief and clear. Washing is one of the most effective cleaning methods. However, due to waste water and the effects on the environment, the industry is shifting towards the dry washing method.

EFFECT OF CLEANING AND SORTING ON QUALITY What can you say on the effects of cleaning and sorting on the quality of flour? What percentage of achieving good quality in flour depends on the cleaning and sorting process of the wheat? What is the role of cleaning and sorting departments in a milling facility?

Mustafa KÖROĞLU Cleaning process aims to protect the milling equipment, the quality of the milling products and the consumer health. Foreign substance content and level of contamination in the milled wheat batch are very important in achieving good quality in flour. From this aspect, purchasing criteria and diligence is paramount. The second issue is the cleaning system used in the facility and the diligence of the user in cleaning. The consequences of a poor cleaning process may go as far as the dinner table of consumers. Its level of influencing quality is not less than 5%. Customer dissatisfaction may have consequences on the prestige of the company, and the process may have different results varying from a return request from the customer to withdrawal from the market. Cleaning process is a very important practice of hygiene and sanitation in a milling facility.

Hüsamettin Ali ÇAĞLAR Producing a good quality of flour relies on the effectiveness of cleaning and sorting processes. Cleanliness of the wheat that is transferred to the first grits roller directly influences colour and ash, which are critical quality characteristics. 60% of achieving good quality in flour relies on the cleaning and sorting processes of wheat. The importance of cleaning and sorting divisions in a milling facility invaluable.

Mustafa KÖROĞLU I cannot give you a percentage. However, as the waste in wheat may lead to an increase of the amount of ash in the flour, it may result in a significant deterioration in quality. Therefore, a facility cannot survive without a cleaning division. The cleaning division plays a vital role. NEW GENERATION OF CLEANING AND SORTING TECHNOLOGIES What are the technologies used in cleaning and sorting and what are the latest innovations in these technologies? What are the highlights of the new generation of wheat cleaning and sorting technologies? Mustafa ÖZDEMİR In a cleaning process, the knowledge, use of technology and an effective and efficient management of a facility are very important. Starting from selection of raw materials during purchasing, taking necessary measures for storage according to the issues identified, and transferring wholesome grain to the tremie of the mill, in good condition and without contamination, are very important. The facility should be equipped with cleaning methods to eliminate all foreign substances and contamination. The leading technological requirement and development of today is passing the goods received from the mill or from the tremie at the entrance of the storage through high-capacity concentrated cleaning equipment, and using the impact method during long-term storage, using colour sorters when transferring the product to milling silos.

Hüsamettin Ali ÇAĞLAR Combined machinery has ensured more effective results and lower energy costs in cleaning and sorting. Particularly in the recent years, quality has become uniform and efficiency been improved in classification and cleaning-sorting processes by use of optical separators. Furthermore, combined machinery and optical separators have helped to decrease operational costs.

Mustafa KÖROĞLU I can say that colour sorters are the most recent innovation in cleaning and sorting. This technology helps to sort grains by colour.

CORRECT CHOICE OF TECHNOLOGY What are the critical aspects to consider when choosing the technologies to be used in cleaning and sorting? What are the criteria to be used to choose the proper technology?

Mustafa ÖZDEMİR In cleaning machinery, the capacity, efficiency, noiselessness, small number of moving parts, lost energy requirements, minimum need and frequency of maintenance, an effective service and positive references are important. To choose the correct technology, it is important to actually talk to the manufacturers of the equipment and the users who can be references. This is important for manufacturers of the machinery as well as for the industries that work with granular products like millers.

Hüsamettin Ali ÇAĞLAR Raw material and desired specifications for the finished product are the fundamental criteria when choosing the technology to be used in cleaning and sorting. The machineryequipment should be selected on the basis of these specifications and capacity. Choosing the correct technology is also proportionate to the product that is demanded by the market.

Mustafa KÖROĞLU The essential aspects to be considered when choosing cleaning and sorting technologies are the capacity, the product itself, contamination level of the product and the area in which the product will be used. The selection should be based on these criteria. EFFICIENT USE OF TECHNOLOGY What does “efficient use of technology” mean? How can we use cleaning and sorting technologies more efficiently and what are the advantages of doing so?

Mustafa ÖZDEMİR If you aim to be successful in cleaning process, firstly you should choose the correct cleaning machinery, and secondly, you should use them efficiently. Our country has achieved international level of quality in terms of production of technology and efficiency. To ensure efficient use, users should comply with the user manual issued by the manufacturer of the machinery, report any defect and malfunctions to the manufacturer and take corrective actions. Returning the machinery would be the best option in case of a defect. Users of machinery should closely monitor the process flow, flow chart, flow rate and effectiveness, always record their operations and follow the operation process. The measures described above as well as an efficient management can only be achieved with institutional knowledge, ability to access advanced information and employing qualified and skilled people who are able to use this technology. These practices help to ensure proper use as well as hygienic quality. We can observe such diligence at mills who have become a brand and have the ability to export.

Hüsamettin Ali ÇAĞLAR Efficient use of technology is, firstly, choosing the correct machinery and equipment. Machinery/equipment may be selected on the basis of the contaminants in the raw material. Thus, through selection of proper machinery, technology can be used more efficiently. Particularly with the introduction of new combined machinery, the advantages offered by less propulsion systems ensure lower energy consumption. Thanks to the compact design used in combined machinery, maintenance and machine cleaning processes take less time, and interruptions in the production process are less.

EXPECTATIONS OF MILLERS What are the expectations of today’s millers concerning cleaning technologies? Can you share your ideas on the basis of the demands you receive? Mustafa ÖZDEMİR Concerning cleaning of wheat, the most common demand received by machinery manufacturers and diagram experts isuser friendliness. Furthermore, machinery with high cleaning efficiency, with multi-directional effect in low numbers, with low costs of mechanization, and with low costs of production, operation and maintenance in the mill are on demand. The demands vary by domestic and foreign customers, by the type of grain to be milled, by the size of the milling facilities and by the addressed industries. Furthermore, it varies from washing or dry systems to equipments with 3-5 machines or 20 machines. The demands of the mills that produce luxury flour and semolina are more comprehensive and they invest more on high-end technologies. Our company and team considers all demands with the possible alternatives and provide information to our customers accordingly. Hüsamettin Ali ÇAĞLAR The expectations of millers can be summarized as combined machines that take up less space, consume less energy, and have less operational costs. This is because in today’s technology, manufacturing takes place in smaller areas and with less energy consumption.

Mustafa KÖROĞLU Millers often demand more combined machinery. In addition to that, machinery that operate on different criteria than the existing machinery are also demanded.

Finally, is there anything you would like to add?

Mustafa ÖZDEMİR After all, cleaning process cover all using processes of milling products, including marketing and consumption type. It may also result in irremediable loss of prestige. Sanitation is the first and most important step in practices in milling. Lack of sanitation may pose dangers for human health, which may go as far as death, as well as it effects on quality and efficiency. Our millers should always follow the criteria for production quality, efficiency and sanitation, starting from selection of cleaning machinery and diagrams to production and operation costs, and should handle construction and operation processes in line with scientific facts and with skilled employees. At İmaş Corp., we wish all millers and our colleagues an efficient, profitable, fruitful services that will benefit our country.

Hüsamettin Ali ÇAĞLAR Before processing the wheat all foreign substances and other contaminants remaining from storage, shipping or harvesting processes should be eliminated. Cleaning these foreign substances and contaminants helps to decrease the amount of ash and number of spects, and ensure a good quality of product by determining the values for colour and taste. Furthermore, the level of wear and tear in the machinery can be decreased, which ensures a long life of the equipment.

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