Pre-milling Grain Cleaning Process and What to Know
Pre-milling Grain Cleaning Process and What to Know

Pre-milling Grain Cleaning Process and What to Know 26.10.2016

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.
 Wheat 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 answered our questions.


In milling industry, what are the cleaning and sorting stages used in pre-milling?
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.


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?
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.


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?
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.


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?
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.


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?
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.


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?
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.


What are the expectations of today’s millers concerning cleaning technologies? Can you share your ideas on the basis of the demands you receive?
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.

Finally, is there anything you would like to add?
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.