The Value-Added Whey
Whey protein concentrate (WPC) is a good example. The bulk of raw milk used in cheesemaking ends up as whey, and the cost of disposing of whey has driven some cheesemakers out of business. European dairy processors have been converting whey into WPC for years, and their American counterparts rapidly are following suit as food formulators find new uses for this ingredient.
But most WPC processes only boost protein content to 35 percent, and they leave behind significant amounts of waste with high BOD loading. More efficient processing is possible, and cheesemakers in states with strict environmental protection laws are taking the lead in applying state-of-the-art technologies.
Cabot Creamery of Vermont is a prime example. The division of Agri-Mark Inc. remains one of a handful of firms worldwide that has perfected a technique to extract lactoferrin from whey. Cabot's Middlebury, Vt., facility began fractionating lactoferrin in 1997. A nutritional supplement for body builders and an ingredient in infant formula, lactoferrin was recently approved for use as a natural antimicrobial treatment in meat processing, an application that likely will increase demand and push prices beyond the $350 per kilogram lactoferrin currently fetches.
Lactoferrin constitutes less than 1 percent of cow's milk. In the cheddar-making process, about 10 percent of milk ends up as cheese, and another 1 percent is skimmed off in a whey separator as butter. Consequently, more than 1.3 million of the 1.5 million lbs. of milk received each day at the Middlebury plant used to remain as byproduct, even after lactoferrin was recovered. When the Vermont Whey Co. announced it would shut down operations in September 1999, Cabot and every other cheesemaker in the state faced a potentially ruinous problem.
"Whether or not you lose money on whey disposal depends on how far you have to ship it," points out Richard Langworthy, senior vice president of manufacturing operations at Cabot's Lawrence, Mass.-based parent, Agri-Mark Inc. "After Vermont Whey shut down, we were shipping it as far as Louisville, Ky."
Agri-Mark engineers were tackling the whey disposal issue before Wyeth Nutritionals announced it would pull the plug on Vermont Whey, but that development lent new urgency to the project. Extracting 80 percent protein concentrate was financially attractive, but it would still leave huge quantities of byproduct. In the end, management decided to produce both WPC and deproteinated whey permeate in a USDA-certified facility so that both products could be sold for human consumption.
Team-building solutionThe Middlebury plant was built in 1975 by Kraft as a Swiss cheese facility. Capacity limits eventually forced Kraft to mothball the unit, and in 1994 Agri-Mark invested $12 million to convert it to cheddar production for its fast-growing Cabot division, a farmer-owned cooperative that merged with Agri-Mark two years earlier.
Specialty cheeses requiring handwork at finishing tables continue to be made in the Cabot, Vt., plant, while Middlebury serves as the co-op's volume workhorse. Fully automated processes enable Middlebury to produce 50 million lbs. of cheddar a year, most of it in 700 lb. blocks. That capacity has fed a tripling of Cabot's sales since the merger.
A rising film evaporator had been modified to boost total solids in the whey to 50 percent, but production growth was creating pressure to find a better solution. Additionally, the Cabot plant was shipping whey that was 82 percent water, adding significantly to freight costs. Ray Dyke, Agri-Mark's vice president of technology, headed a team that was working with research centers and dryer manufacturers for a total whey solution. Extensive calculations had to be performed to determine equipment capacity needs to handle the plant's whey. The team included project engineer David Brault.
A 54,400-sq.-ft. refrigerated warehouse project to consolidate cheddar aging in Middlebury was completed in 1999. Stahlman Engineering Corp. worked on that project, and John A. Russell Corp. served as general contractor. Agri-Mark managers invited the two firms to participate on the fast-track whey project, which required extensive negotiations with state officials on permit requirements. The goal was to complete design, construction and permitting in little more than a year's time.
"Russell Corp. really drove it," according to Brault, an electrical engineer by training and temperament. "Their construction management skills are tremendous." More than 600 people were involved in the project, with as many as 110 construction workers reporting each day beginning in November 1999. Strict safety rules were enforced, with stiff fines and dismissal from the job site accruing to violators. The payoff was a smooth start-up and validation in September 2000, with no reportable injuries during the project.
Turnkey systems for both WPC and permeate drying are nonexistent, so project managers pieced together a multivendor solution. Hudson, Wis.-based Niro Inc. provided all the membrane filtration and packaging equipment, C.E. Rogers Co. of Mora, Minn., fabricated the dryers, Columbia, Md.'s Zimmer Evaporation supplied the evaporators and DCI Inc. of St. Cloud, Minn., delivered the crystallizers. Integration work was performed by Sherping Systems Inc., Winstead, Minn.
Separation and extractionRecent advancements in membrane technology made the project commercially viable. Some membranes permeate water and retain all the solids; others retain protein but allow water and minerals, including sugars, to pass for further processing. Multiple membrane systems such as Cabot's leave cow's water as the only byproduct.
After whey has been clarified and fines removed, fluid is routed through a pasteurizer and into 10,000-gallon storage tanks. The whey then goes through an ultrafiltration system that boosts protein to 35 percent. The resulting protein concentrate undergoes chromatographic separation to extract and concentrate lactoferrin. The 35 percent WPC then is pumped to a diafiltration system to increase protein concentration to 80 percent. The filtration system's PLCs feed data via an Ethernet connection to the plant's control room. Flow meters on the shop floor are clearly marked and coded, and flow direction through every pipe is labeled, simplifying maintenance and repair tasks.
With protein content removed, the remaining fluid moves to a permeate pasteurizer before undergoing reverse osmosis to remove two-thirds of the water. The RO concentrate then is brought to 60 percent total solids with a falling film TVR evaporator. Next, the concentrate is pumped to one of five 6,000-gallon glycol-jacketed crystallizers, where sugar crystals will be formed in a highly viscous fluid. Significant agitation is involved in this controlled cooling process, which takes 18 to 24 hours. "You'd think you were stirring up molasses," Langworthy says of the resulting fluid.
"Separating the sugar and drying it to create free-flowing sugar crystals is a challenge many have been stymied by for years," he adds. "This process has worked from day one, and that's quite an accomplishment."
Only six people, including two in packaging, staff each shift, so the control room is critical for monitoring conditions throughout the facility. Several communications protocols had to be interfaced with the various equipment manufacturers's controls. Brault applied his electrical expertise to include an uninterrupted power supply (UPS) to avoid any false faults along the multiple data highways. Power distribution to all motors is accomplished through a new electrical room, where the UPS unit is housed. The whey facility required high-voltage service, including a 2,500 KVA transformer and main switchgear. One remote I/O panel controls all the plant's power. "There are miles and miles of wire in this plant, and they're all controlled here," Brault points out.
The electrical room accommodates 152 AC drives in 16 panels. Before work commenced, Brault created detailed drawings that tracked the precise path that every wire in the field devices would take to the panels. The drawings removed any guesswork for the 34 field electricians who worked on the project. "Everything started up in about two weeks," Brault proudly notes.
After leaving the crystallizer, fluid is sent to a multi-stage drying system. During this process outside air is heated with propane and mixed with atomized permeate that is pumped under pressure of 5,000 to 6,000 psi to the top of a 90-ft.-tall drying chamber. Residence time dictates the height of the dryers, with somewhat shorter units needed for WPC drying. The WPC dryers also are narrower, with a 14 ft., 10 in. diameter at their widest point. The permeate dryer measures 18 ft. in diameter.
Cyclones recapture most of the permeate that doesn't fall to the bottom of the dryer. A timing belt at the base of the dryer conveys permeate through a fluid bed dryer, after which the material is pumped pneumatically to the top of a storage silo at a rate of 5,400 lbs. an hour. At this point, moisture content has been reduced to about 3 percent, compared to 94 percent at the beginning of the process. Permeate is packaged in 1,000 lb. totes and 25 kilo bags. Five days a week, three trailer-loads of packaged permeate are hauled away, to the tune of 35 million lbs. a year.
By the end of the process, virtually all solids have been removed, leaving only 155,000 gallons of water. Some of that water is routed through a polisher, then through a UV system before being chlorinated for use in plant washdown and in two 900 HP Nebraska boilers. The remainder can be safely discharged into the municipal waste system.
The WPC dryers were trucked to the construction site, but the permeate dryer had to be fabricated in Middlebury. A 2,500-sq.-ft. slab was constructed next door for that purpose. It was built in two sections and erected when the building's steel frame reached 72 feet.
"We built the dryer plant to be the most efficient possible," reflects Brault. "In the future the technology will be even more efficient, and I don't see us sitting still. For now, we've got one of the most modern facilities in the world, it's USDA certified, and we're putting out a quality product at a competitive price."
Before seeking the go-ahead for the $21 million project from Agri-Mark's board of directors, Langworthy had to establish that there was, in fact, a market for sugar and mineral granules, which essentially is what permeate is. That led to a partnership with Century Foods of Sparta, Wis., which sells most of the permeate overseas. Uses include coatings for pills and Korean aphrodisiacs.
Drying whey is an energy-intensive process, and permeate fetches prices one-tenth that of WPC. Nonetheless, Langworthy expects a return on investment within a few years. And the project resolved issues that dog the entire cheese category. "If you're a major cheese producer, you're in the whey business, whether you want to be in it or not," he says. "Shipping it out wet is too costly, and it leaves a lot of money on the table. And we're developing new applications and uses for permeate, such as a low-cost filler for some bakery products."
Other cheesemakers also are taking advantage of the advances in whey processing technology. Leprino Foods, for example, recently updated the WPC and permeate drying process at its massive Roswell, N.M., mozzarella plant. But Leprino's process produces a 35 percent dry WPC or 60 percent liquid form.
Who did it first or does it best isn't the point; rather, it's that processors are demonstrating the technological savvy to convert a byproduct that once was dumped on farm fields and turning it into a value-added product with new and expanding uses. The reward for those efforts is a new business model that will serve those companies well in the 21st Century.