Processing progress

by Emily Buckley
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For the milling industry, there have been numerous equipment developments introduced in the last 20 to 30 years. Some would argue that nothing truly ‘revolutionary’ has emerged in that time frame, but millers seem to disagree. While most equipment introductions have been more of an improvement of an old method rather than a truly new idea, millers around the world herald their affects on the milling process.

World Grain surveyed six milling experts from the U.S. and Latin America to discover exactly which developments introduced during the last several decades have served to evolve milling operations.


Developments in tempering equipment might have been the most dramatic, as several millers noted its influence.

One of these millers is Henry Stevens, president of Stevens Technical Services. Formerly with the U.S. Wheat Associates, he has worked with mills worldwide.

"As a wheat flour milling technologist, I have to say that the biggest improvement in the milling process over the last 30 years or so has been in wheat tempering with the development of automated moisture control systems and modern mixing technology," he said.

He also explained its many benefits. "The capability to maintain very close control of moisture content and very consistent mixing has allowed the development of today’s very ‘short’ flow diagrams, minimizing capital investment and power requirements per unit of

capacity," he said. "Wheat conditioning has three critical components: adding the correct amount of water, mixing it well, and letting the wheat rest while the moisture penetrates. Unfortunately, the last of these three is poorly controlled in most mills, even though the technology is simple and has been known and available at least as long as the first two. Application of this technology, especially in new construction, would further minimize capital investment per tonne of capacity by reducing the required rest time while further improving the operation of the mill."

Stevens is not alone in his opinion. Kendall McFall, with Kansas State University’s International Grains Program, also believes the tempering mixer and automatic wheat moisture measurement equipment have meant the most to millers.

"More than half of the problems associated with mill balance, throughput and milling extraction are caused by improper moisture addition," McFall explained. "[Tempering] mixers helped to improve the miller’s ability to apply the water to all kernels evenly by bringing the kernels into contact with the water in a rapid, uniform fashion. Automatic moisture measuring has allowed the miller to make swift, accurate adjustments to the amount of water added to wheat; thus providing a way to manage a frequently changing raw material. This device helped the miller by reducing the magnitude of moisture fluctuations of the wheat at first break, thus improving mill balance and loading."

Aside from tempering, others noticed significant improvement in cleaning systems. Ivo Klaric, head of operations at Molinos del Ecuador, commented on their added ability to diminish bacteria content. In addition, combined cleaning machines have allowed space and energy savings, as well, according to Macro Fava, technical manager at the Chile-based consulting group, Grainmade.


No one can deny that the emergence of the affordable, versatile and multi-purpose personal computer has changed the working environment of nearly every industry in the last 30 years. While the computer and software industry development may not necessarily qualify as a revolution for the milling industry, it certainly enabled the most dynamic new sector for milling — automation. Most millers agreed that process control systems have contributed to the greatest change in the flour milling plant.

"The microprocessor and the devices that feed it have served to increase the millers’ overall process control," McFall said. "There are devices that monitor the flow of product, motion sensors monitor the movement of shafts and sprockets, laser beams are used to detect product spillage, electronic scales can be used on nearly every input or output stream in the plant. All these devices (and others) can provide information to the miller as to how the mill is performing. In addition to the information generated, the computer has provided the miller a way to have decisions made to benefit the process without human involvement. Bins can be changed, systems can be stopped and started, and the mill itself can be shut down or suspended while the operator is notified of a needed adjustment."

Hand in hand, automation has brought with it a clarity and vision of the total perspective of mill performance.

"The automation related with the wheat mixes, water addition, and extraction rate has provided the miller with an enhanced vision of the process that makes it easy for him to fulfill the company’s objective goals and the market’s expectation for quality," said Marco Fava. It would be impossible to meet the quality standards that the current industrialized market requires without the proper control equipment, he explained. To be able to analyze the product characteristics on a "just in time" basis with today’s laboratory equipment allows the production department to be certain that the required product specification is fulfilled, and if not, necessary changes can be made before the product reaches the client.

Yet automation is not without its challenges. According to Jeff Gwirtz, head of JAG Services Inc. and formerly with Kansas State University’s Grain Science Department, automation has changed the skill sets needed by mill staff, requiring knowledge of circuit electronics and programming specialists. And as automation has allowed for staff reductions, Gwirtz wonders about a resulting decline of milling skill on the mill floor.

"Most mill operating employees today have the computer savvy to operate automated mills but may lack an understanding of the principles of milling that are the foundation for trouble shooting skills needed to maintain optimal mill performance," Gwirtz said. For management, automation and data acquisition has forced mill managers to master data analysis and statistical process control techniques.

A shift from mechanic to electric technology also has had a large affect. Klaric noted particular progress beginning 15 years ago in Latin America when mechanical scales were replaced by electronic scales. Other upgrades in technology led to better drives as well, which have been particularly utilized in the flour blending system, Klaric said.

Klaric did add a note of reality. Despite these many improvements, due in particular to microprocessors, he warned that cost is still a limiting factor for many mills. "Not every mill in Latin America wants to invest money in this kind of technological advance as the cost/benefit is hard to justify," he said.


Other millers found it hard to narrow their list of favorite improvements down to just one area of milling equipment.

Gary Pickelmann, corporate milling superintendent of Michigan, U.S.-based Star of the West Milling Co., said there are many things that have had a tremendous impact. His top choices

included pneumatics, compact milling and double-high rollermills, automation, high-capacity sifters with new glue-on technology and new sieves styles, and enhanced storage and blending of inbound as well as outbound products.

"These few items have had the biggest impact on all of us as flour millers," Pickelmann said. "It certainly has made it much easier for us to produce a top quality product that is always well within the specifications of our customers."

Pneumatics, he explained, have improved capacity throughputs and also delivered tremendous sanitation improvements over the old wooden bucket elevators and wooden trough screw conveyors.

Short-flow milling and double-high rollermills have allowed for milling unit installation in a very compact area, which quickly and economically allows for extra capacity, he said. In conjunction, with high-capacity sifters, glue-on technology of clothing and the new style sieves and cleaners, we have seen much improved sifting and capacity abilities and less maintenance, which always benefits the bottom line, he added.

Sanitation is an ever-constant challenge for mills, and many millers appreciate enhanced sanitation features on equipment. "The easier it is for the worker to clean the machines, the more the workers will do it," Fava said.

Pickelmann believe the biggest benefit of new equipment models is sanitary design. "Our equipment suppliers have come a long way and have made huge strides to improve the sanitary design of equipment," he said. "We need to continue to work together as millers and equipment manufacturers on designing equipment that is functional and also easy to clean and stay clean."


For a bit of fun and possibly as inspiration to milling equipment suppliers, we also asked millers to dream a little and describe a piece of equipment that they wish could be designed for milling.

Several millers desire a mechanism that could enhance the sampling analysis of wheat quality to shorten the response time for necessary mill adjustments.

Kendall McFall’s dream to have a ‘black box’ that provides a true measure of wheat quality in a rapid fashion illustrates this much-wanted control tool. "This device could ultimately replace much of the current wheat grading system, while further allowing wheat to be traded on its functional quality (with functional quality defined as the wheat’s milling yield potential and end product baking potential).

Henry Stevens has a similar wish. "I need an instrument that can quickly, reliably, and easily indicate the processing and end-use characteristics of a sample of wheat," he said. "Pour wheat into the top and in 30 seconds you get a printout with total impurities, moisture, endosperm content, gluten and starch characteristics. If you give the grain handling industry that instrument, we millers will say, ‘OK, now you have a way to measure and segregate wheat based on its true value to the processor and end user.’"

Ivo Klaric warned that his new concept might "sound a bit too revolutionary to accomplish." But he continued, "I believe the concept of milling could be redesigned by replacing rolls with pressing plates that break wheat kernels and reduce middlings much faster and possibly with less power consumption. The theory is simple, as with the plates you could have more contact-surface than the small milling gap with the rolls."

Jeff Gwirtz hopes to see a new method to remove endosperm without shattering the bran. "Something better has got to come along!" he said. His dream system includes a tool to focus an adjustable energy source onto the kernel causing the complete breakdown between the chemical and/or physical bonds holding the bran, germ and endosperm together to reduce endosperm size to flour while keeping the bran and germ intact," he said. "Imagine getting 83% extraction of low ash flour with no germ, bran or aleurone layer contamination!"

Gwirtz offered a long wish list, including sieve cloths that prevent ‘blinding over’ and a roll brush scraper tool to prevent premature brush wear and maximize cleaning performance.

What the next 25 years will hold for new milling equipment developments is impossible to forecast. But millers and suppliers alike can be certain that these many developments already in use have allowed mills to better utilize their capital investments with higher throughputs and most importantly resulted in a better end-product.