©xreflex – stock.adobe.com
By Matt Noltemeyer
September 2022
Future is now for
milling technology
Incremental advances improve highly efficient, labor-light flour mills
©xreflex – stock.adobe.com
Agrain professional’s device pings early on a Wednesday: A VP has a VIP in need of 30,000 cwts of bread flour, ASAP.
Since the mill had cake flour grind scheduled today, the worker mentally tallies the steps to make the switch.
He pours a coffee, commutes to the cozy cockpit of his home office, fires up the machinery and completes an authenticator eye scan.
A few taps at the tablet and he’s put the cake flour grind on hold. A few more taps and the line, in the plant a few miles away, begins to make the necessary adjustments for milling hard red winter wheat into bread flour without ever turning the lights on.
Another couple keystrokes and the soft WIP — work in progress — wheat is set for a few more hours in the temper bin. Next, the automated mill dutifully collects a precise volume of winter wheat, dampens it with the additive solution that will have the bran toughened just right and the endosperm appropriately mellow by the mid-morning coffee break.
During the grind, the mill will continually monitor quality parameters and issue data on each wheat berry. Should a problem arise with the specs or a mechanical part, the mill will divert product to a holding bin while troubleshooting takes place, avoiding a mess on the floor. A self-regulating pneumatic system will convey just enough product to avoid wasting energy and adjust automatically if the flow rate deviates.
A scene from a wheat miller’s dream?
Yes and no.
More precisely, that tableau mixes technologies already used in many flour mills that are expected to become more refined, more efficient and more commonplace in the coming years, with what some see as “the Holy Grail of wheat milling.”
On the occasion of its 100th year chronicling the evolution of milling in the United States and reporting on the commodity markets that feed the world, Milling & Baking News, a sister publication of World Grain, spoke with milling experts about the technological leaps, bounds and baby steps that led to the modern flour mill; where flour production technology most likely is headed next; and what improvements will transform the industry when value-added solutions to age-old problems emerge. Some milling equipment manufacturers were reluctant to be interviewed because they didn’t want to give away ideas they were working on or developing.
Millstones and pneumatics
In the beginning there were millstones. By the 15th century, millers began to work out the grind-sift-grind process to reduce the kernel, endosperm and bran into flour. Innovations such as the roller milling system in the 1870s revolutionized the industry to a degree that perhaps hasn’t yet been eclipsed. After all, rollers endure as the foundational technology in the world’s newest, largest, most efficient flour mills.
Incremental advances consistently reduced the mill labor force, eventually eliminating such roles as smutters controlling the clearing house, bolters steering the sifting house, truckers tugging the hand carts. By the 1950s, longer-lasting parts meant equipment broke down less often. When pneumatic conveying superseded bucket elevators, mills became cleaner, safer places with fewer sweepers.
“The genius of the gradual reduction system of milling is that a mill can produce multiple grades of flour contemporaneously, fine cake flour, pretzel flour, cookie flour,” said Richard Siemer, president of Siemer Milling, Teutopolis, Illinois, US. “We can blend it back and forth and sift it apart. Milling technology, at the heart of it, is innovations that took place in the 1700s and the middle-1800s. For the most part, in the 20th and 21st centuries, what we’ve been seeing is just refinement. If we could resurrect a good miller from a good mill who died in 1900, bring him into a modern mill today, he’d understand the process almost immediately. You would, of course, have to train him on computers, and the scarcity of mill workers would be part of his cognitive dissonance.”
For the near term, more such incremental improvements to existing technologies are expected. For example, while pneumatic cleaning systems are more sanitary, they tend to use more energy than mechanical sorting. The US power grid amply provides for that. But in other countries and with customer expectations trending green, there is an opportunity to raise the efficiency of the cleaner technology.
The new mills that have come online in the past five years are some of the largest in the world, a trend that’s likely to continue.
“If you check into Sosland’s Grain & Milling Annual archives, as I do from time to time, and you look back into the 1980s, 10,000 sacks a day, or 600 tons, was a pretty big mill, but I don’t think that would make the list of the 25 biggest mills in the states today,” said Scott Martin, senior director of technical milling with Ardent Mills, Denver, Colorado, US. “Back then, I worked at a 10,000-sack mill that had two sifter floors, 17 individual sifters, holding about 94 sifter sections. A modern 10,000-sack-a-day mill has maybe four sifters and maybe half as many sections. Fewer machines, bigger machines make for more simplicity, fewer labor resources, which are good improvements, and it’s good to see progress.”
NIR and working from afar
A flour mill today is an efficient, computerized version of the roller mill and gradual reduction systems in place for many decades. Millers who in the 1960s looked to floor spills to spot problems now have a real-time understanding of how each element in the plant is performing, all viewed from screens in a control room or even from another location. That area continues to expand with each generation of technology introduced. The miller who in the 1970s regularly replaced worn belts to avoid potential fire hazards now runs lines mostly controlled by direct drives and, increasingly, variable frequency drives to run fans, airlocks and other components intelligent enough to sense a potential stoppage and divert product before the elements likely to cause combustion align.
The arrival of NIR, or near-infrared reflectance, meant millers no longer had to manipulate samples with their fingers or take them off site to a lab where a technician with a scale and an oven took four hours to test the product. NIR shortened the wait to minutes. Moving the data analysis computer to the mill streamlined things, as did training millers to calculate their own results. The latest updates automated the process and moved it online.
“Knowing the quality of flour is important, and if it can be done automatically, it frees the shift miller to do something that can’t be done automatically, plus the mill and its customers get a better measure of quality because we’re measuring it all the time,” Martin said. “If a quality parameter isn’t where it needs to be, we can divert that product to a different storage bin, do some troubleshooting and know we have that product isolated for corrective action. A mill has to have the resources behind it to keep the instruments calibrated, and with most now on a network, it’s all about whether the network is strong enough. It’s a pretty exciting part of where the industry is going.”
These technologies and other examples of mills essentially running themselves are the future of flour milling, experts said. Already there are autonomous mill tracks in place that can run without a human in the building. It’s commonly called lights-out milling because when the miller leaves the area and the sensor times out, darkness ensues, but the mill continues to clean, sort, sift and grind.
Multinational equipment manufacturers such as Bühler are striving to stay at the forefront of automation innovation.
“Their ambition is to create an autonomous mill that really could operate by itself if a company wanted to or needed to,” Siemer said. “You can’t eliminate the human factor, but it’s another step toward automation.”
As the 21st century rolls on, experts foresee manufacturers such as Bühler incorporating more electronics, more sensors, and enhancing multi-point sensor-based data collection. Essentially, sensors present real-time data on the temperature of the equipment, vibration, throughput and many more that comprise a massive trove of measurements being taken every second. Mills have to figure out what data are important for their grind and how to apply it toward improving the process. That typically means using data to improve mill yield, to keep flour products within specifications and to run in the most energy efficient way possible.
“The challenge is doing something with the data to tell us more about flour quality and productivity and energy usage — that’s when the data adds value,” Martin said. “You have to have the means to analyze data and then put value into what the data tells you. We’re just on the cusp of that. We’re starting to have roller mills that can tell us about roll temperature and roll force and kilowatts consumed — all toward reaching maximum efficiency and productivity.”
Another key benefit? Integrated control systems that join on-site and remote management enabling remote troubleshooting.
“In our case, working with Bühler, a miller can literally dial up Switzerland or Minneapolis and ask that person to get online and view the operating parameters and consult on what to do about it,” Siemer said. “Software suppliers can open the hatch, get inside and try to diagnose your system. Millers in different locations of the same organization can also share information with each other. It’s something we’ve just been able to do within the past few years, to call on experts, reliable people from different places and have them actually participate in the troubleshooting process in real time.”
As US flour mills continue to migrate to new technology and processes that are more autonomous, there will be a need for skilled mill workers schooled in the new and the old, said Kent Juliot, vice president of research, quality and technical services with Ardent Mills.
“Even in 10 years, the industry will still have older mills, so you’ll need people that know both sides, those who can manually adjust mill rolls but also understand the logic of an automated controls system,” Juliot said. “With labor shortages, newer systems can reduce the number of people needed, but the pressure from the technical side will be even greater, because the education and knowledge will have to span all the way down to just above the waterwheel. The future of milling is going to be exciting and new, but we can’t forget the old.”
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Sorted and binned
The methods for removing corn, soybeans, husks, straw and other dockage from incoming wheat were once limited to a basic separator and a scourer to clean out the dust from the crease. Mechanical cleaning gave way to aspiration, which paved the way for precision grain cleaning systems such as the color, or optical, sorter. It’s the closest thing to a revolutionary technology the industry had seen in about 60 years.
These cleaning systems combine sophisticated cameras with precision equipment using sharp blasts of air to knock out impurities that may have commingled with wheat at an elevator or aboard a rail car. It eliminates non-grain contaminants and sorts supplies by characteristic. Color sorters have improved consistently since their debut. Today, most all new plants employ them, and many older mills have retrofitted them. The technology has moved from black-and-white to color cameras and now to infrared scanning. Sorting technology today allows mills to better handle damaged wheat. For example, it can salvage more good wheat from a shipment with elevated dockage, disease such as scab and other mycotoxins, such as vomitoxin. It’s clear to experts that the future holds further refinement of optical sorting technology.
“Mill technology keeps improving, and if we think to the future, the technology in sorters will probably blow our minds in ways we can’t even dream of right now,” Juliot said. “For example, they currently use spectral analysis that can give you an actual analysis of each individual wheat berry and, in my opinion, they’ll become amazingly high-tech in the foreseeable future.”
Cleaning out impurities relies on the color sorter, which compares kernels with references it’s already learned, and reacts quicker than any human ever could. But what of the nearly invisible threats to food safety, the mycotoxins? Cutting-edge technology on the horizon aims to eliminate them with a method more efficient and economical than ever at a time when the US Food and Drug Administration has indicated pathogens are on their radar and near the top of their list.
“Pathogens are right up there with leafy greens and everything else on FDA’s list, so having a mitigation step in place, they expect you to have it,” said Brad Allen, chief technical officer at PHM Brands, Denver.
Several methods of handling this problem are on the horizon. One of those already operates at PHM’s Dawn, Texas, US, plant, having been adapted for the food industry by PHM Brands’ Energis Solutions in a joint venture with the technology’s inventors. Energis is manufacturing equipment that produces a treatment solution on site. It yields a similar reduction to other systems developed since the turn of the century 22 years ago, “but we’re doing the head end of the process, so you’re not making a ready-to-eat claim like other methods do, but you’re getting the brand protection and you’re not going to get a recall,” Allen said.
The advance of that and future pathogen elimination technologies could spur adoption of an industry-wide standard, a development that would please Siemer.
“It’s not something I’d like to make any money on as a proprietary advantage,” he said. “I’d just like to have everybody agree that we’re going to use it for certain products. And I’d like to see it applied to flour rather than wheat, because that gives you a lot more flexibility. Unfortunately, none of the systems that I’m aware of right now are used on flour, they’re used on wheat before milling. It gets kind of complicated. I know it’s significant right now, and I think it’s going to become more so.”
Genomes and unknowns
Some of the innovations likely to shape and shift flour production in the future are beyond the horizon for now. Breeders manipulate wheat to create varieties more likely to thrive in certain growing environments or to increase resistance to disease pressure. At some point, experts said, biotechnology and research in the wheat genome will generate some major advances to the milling process of flour production. That may have to do with the ease of processing the kernel, adjusting qualities such as protein, reducing gluten’s impact on those afflicted with celiac disease, or increasing gluten strength for use in pizza doughs, variety bread, and perhaps even pancakes.
“As long as wheat quality is, as they used to say, 70% nature and 30% nurture, or 30% genetics, 70% environment, you’re not going to be able to be really precise, but I believe that biotechnology will soon have the biggest impact on the wheat foods industry in a positive way,” Siemer said. “If as many resources had been put into breeding wheat as have been put into breeding corn over the past 90 years, we’d be a lot further along, but that’s our particular cross to bear.”
Near the top of Siemer’s wish list is a boost to soft wheat resistance to alpha-amylase activity. That’s an enzyme in the wheat that starts to break down the endosperm shortly after the kernel is fully ripe, especially if moisture is introduced via rain on a mature, ripe crop. It leads to sprouting, which reduces the viscosity of the flour and locks it out of some applications, such as pie crusts.
“If wheat could just sit out there in the field for a week without degrading, as distinct from sitting out there for an hour if it starts raining, that would be enormous for the milling quality of wheat and would be one factor in the attractiveness of wheat as a crop here in the eastern Corn Belt,” Siemer said. “It would be more reliable. Farmers would know when they harvested it that it would be of good quality.”
After quality is established, wheat headed for the mill typically stops off for a lengthy stay in the temper bin to ready the kernels for efficient sorting. Of all the advances in milling over the years, the temper time has proven a tough nut that’s yet to be cracked.
“One thing that hasn’t changed over the years is the miller’s desire for 24 hours of temper time for milling hard wheat,” Martin said. “If we could find a means to achieve the physical changes to the wheat kernel in a shorter time, it would be greatly beneficial. Bigger mills require more space for work-in-progress, or tempered, wheat. Bigger bins mean greater capital investment.
“Also, if the mill is grinding spring wheat and the flour silos get full, I still have all that spring wheat WIP in my temper bins. I can’t change to another grist, so the mill has to stop and wait for space to come available in the flour silos. Mills with a 24-hour temper time have to know what they’re going to do tomorrow today. They can’t turn the mill on a dime so to speak.”
There have only been marginal improvements in tempering over the past few years. A step-change in technology to shorten the planning cycle or the development of an additive to reduce temper time to just a few hours but retain the effects for optimal grind is seen by the industry as a Holy Grail because of the flexibility it would enable.
“If there were a way to do that,” Juliot said, “it would be transformative.”
Until such an innovation comes along, improvements in flour milling efficiency, efficacy and food safety will continue to be incremental, millers and grain industry leaders say. And that’s not a bad thing, Siemer noted.
“I heard a miller say 45 years ago in one of my first months in the business, ‘I’d hate to be the person known for building the last grind-and-sift flour mill,’” he said. “But honestly, we’ve gone for all these decades, and nobody has come up with a better way of making flour, so we’ll see what happens.”
