“Ours is the newest bun bakery in the quick-service-restaurant (QSR) supply chain system,” said Tony Taddonio, CEO, Mile Hi Foods, Denver. For its new 128,000-sq-ft facility, Mile Hi Bakery deliberately sought the next level of speed and capacity to bring output to 5,400 doz per hour.

But the new plant team and bakery managers had additional objectives. “We’re actually more than just faster; we’re more flexible,” said Bakery Director Bryan Sanchez. “And we’re more sustainable in terms of plant and people.”

Among the “next generation” technologies employed at the new bakery are a batching system that’s flexible but not complicated, a divider that can handle doughs from soft to stiff, a topping/splitting system that maximizes variety options and packaging methods to accommodate needs ranging from “dozen” bags to 30-count bulk packs. “We built in the capacity to serve markets beyond the QSR field we now supply,” Mr. Taddonio said. “This is very much the model for European bun bakeries.”

Taking the LEED

Leadership in Energy and Environmental Design (LEED) Gold certification is a primary objective for the new bakery, which it is well on its way to achieving. The project team planned to make the facility among the first bakeries in the US to earn this status.

Rather than chemically seal the production hall’s concrete floor, Mile Hi opted to polish it instead. It retained the original floor of the building, except for adding drains and footings for the heavier equipment. “The concrete was polished smooth with a diamond-tipped head and is easy to clean with simple washing solutions,” Mr. Sanchez explained.

Energy and water savings figured into other renovation strategies. Mile Hi removed the river rock that anchored the roof and used it for landscaping. The new roof, a TPO R30-rated white membrane, reflects light and heat, keeping the bakery cooler and cutting the “urban heat island” effect of older styles. Low-water-flush fixtures enable water conservation. And the Newsmith Dual-Lane tray washer not only uses cold water only, but it also recycles half its wash water to further conserve resources.

“We don’t have a boiler in this bakery,” Mr. Taddonio observed, “because heat recovery is part of our management approach.” Excess heat from the ammonia compressors is channeled into the freezer floor to maintain temperature balances. And heat generated by the catalytic oxidizer, reburning oven exhaust at 1,200°F, supplies the plant’s heating and hot water needs. The oxidizer eliminates 95% of VOCs in the exhaust stream, which more than meets the regulations of Denver’s air quality district.

The existing 21 domed skylights were replaced with prismatic structures. “These bring in significantly more natural light than standard domes,” Mr. Sanchez said. Lighting technologies in the plant combine low-mercury systems and LED lights for the offices, conference room, freezer and fitness areas. Multilevel lighting and occupancy sensors automatically control with step dimming features. In all, lighting accounts for more than 17% in all energy savings.

Equipment choices also earned LEED points for improving energy use. Mile Hi managers estimated that the production line consumes 80% of the energy used in the building, but it also provides roughly half of the energy savings earned by the new bakery. For example, energy-efficient SEW Eurodrive variable frequency drives power the mixers and conveyors.

Sustainability is a company-wide commitment. In 2013, Mile Hi Foods was named Sustainability Company of the Year by the Colorado Women’s Chamber of Commerce for its workplace culture that supports sustainability efforts. During the same year, Mile Hi received the Green Fleet Award from the Colorado Motor Carriers Association.

Following the line

The new Mile Hi Bakery devotes the bulk of its space to processing (60,000 sq ft), packaging (5,000 sq ft) and warehousing (80,000 sq ft). The single-line operation has room to add two more lines. “This building is for today and the future.” Mr. Taddonio said.

Mile Hi’s food processing operations hold SQF Level 3 certification for food safety, achieved in 2012 and renewed the following year at the same level. “We’re going for ISO 14001 this year,” said John Borowski, vice-president, corporate services and bakery, Mile Hi Foods.

The company again chose Stewart Systems as its lead equipment vendor, the same at its first bakery. The line is fully integrated with Allen-Bradley PanelView Plus color touchscreen control terminals at each operator station throughout the plant.

Not everything happens inside the bakery, however. Mile Hi installed its bulk tanks outside the building. The Pfening system holds flour, liquid shortening, liquid sugar and cream yeast. Tanks are heated or cooled to match environmental conditions, but mainly it’s Mother Nature who handles such matters. “Outdoor installation is possible because we get 300 days of Colorado sunshine in Denver,” Mr. Borowski observed.

Plant configuration features straight-line layout for its processing equipment. “The in-line design eliminates a lot of the curves you’d find in a typical square-box ­bakery layout,” Mr. Sanchez said.

The result is an open, airy installation. “With this much open space, it’s much easier to work here,” Mr. Taddonio noted. Most conveyors run overhead except where waist-high access is required. There’s been no need to install step bridges to help operators climb over the line.

Computers automatically deliver bulk dry and liquid ingredients to the Pfening supply hoppers above the Shaffer (Bundy Baking Solutions) mixers, but for handling smaller ingredients, the company established a separate scaling room at the front of the line. Operators weigh dry minor and micro ingredients in batches. Following the production schedule, the operator pours the batched materials into the Pfening bag dump to be pneumatically blended and sent to the mixers. Liquid ingredients are incorporated via a QDS slurry mixer and transferred to the mixers. Bulk totes containing liquid ingredients are also housed in this ingredient room.

“In batching, we deliberately use a less sophisticated system,” Mr. Sanchez explained. The system provides the desired flexibility Mile Hi wanted because it’s computer-interlocked, requiring operator acknowledgment of each batch.

The bakery follows sponge-and-dough methods to prepare its buns. Two Shaffer mixers stand side-by-side. The smaller prepares sponges, which are dumped into troughs and sent into the Stewart Systems automated fermentation room. The 14-trough system moves each batch through five punch-down stations before it emerges in front of the large 3,200-lb final mixer.

The final mixer kicks finished doughs out into a Bundy automatic dough pump. As another trough-full of dough enters the mixer, the finished dough leaves as a continuous stream extruded by the pump into a steeply inclined dual-belt conveyor system equipped with a Mettler Toledo metal detector to monitor the dough ahead of the AMF DoFlex rotary divider.

“We chose this divider for its ability to handle doughs from very stiff to very soft,” said Bakery Director Paul Chan.

Baking at a mile high

With a run goal of 135 cuts per minute, the divider portions dough pieces in an 8-across configuration, depositing them onto the moving conveyor of the AMF Accupan’s chilled-surface rounding table. Pieces roll along the high-density plastic rounding bars and drop into the zig-zag board. Dusting flour showers the dough pieces and is reclaimed by a W.D. Laramoor dusting flour collector system.

Proofing and baking operations at Mile Hi will seem familiar to most bakers, but Denver stands 5,280 ft above sea level. “Remember, we’re doing this at elevation, so conditions are a bit different,” said Marc McCarty, production superintendent.

While chemically leavened baked goods are more sensitive, yeast-raised products are also affected by ­elevations above 2,500 ft. Specifically, they get fluffier. Gases expand at greater speeds, water boils at lower temperatures, and moisture evaporates at faster rates. This means that yeast-raised doughs ferment faster and proof quicker, at differences approaching 20%, according to cereal scientists. Baking adjustments change both time and temperature. Higher elevations also tend to be lower in relative humidity, which requires bakeries such as Mile Hi to regulate their air systems carefully and package finished products quickly.

The AMF Accupan bun system gives dough pieces their intermediate proof then passes them through a belt moulder to be flattened. The system can accommodate roller accessories for giving buns patterned creases and indentations. The flat buns slide into waiting pans, indexed forward to accept five rows each.

This bakery uses DuraShield release-coated 40-cup pans from Bundy Baking Solutions for several varieties. The old plant used 24-cup pans for the same products. Burford orbital pan shakers intercept filled pans and gently seat each dough piece in the pan cup’s center. All pans run through the system with their long edges forward, thus maximizing throughput and minimizing conveyor speed. The grids carrying the pans use magnets to ensure stability.

The round hamburger buns running through the Stewart Systems conveyorized proofer during Baking & Snack’s recent visit to Mile Hi were proofed for 55 minutes at 102°F and 82% humidity, according to Mr. Taddonio. These are standard conditions for most products, according to Mr. McCarty, and the proofer adjusts readily to handle specialty styles.

The design team for the new bakery deliberately lengthened the distance between proofer and oven. This longer-than-usual run-out allowed placement of specialized topping systems: a Burford Smart Seeder and Splitter/Topper. The line can, thus, handle many different toppings — sesame seeds, poppy seeds, cracked wheat, flaked oats, etc. — and make split-top designs, too.

“This is another way the bakery advances our product opportunities, as does the divider’s ability to handle widely varying dough types,” Mr. Borowski added.

The Stewart Systems conveyorized oven is subtly different from comparable systems at other bakeries. For one thing, it is taller because the bakery wanted the ­option of extra baking time for future varieties. Also, it contains an internal steam tunnel. “The tunnel allows us to bake crusty rolls and artisan-style products — a new feature,” Mr. McCarty said. The tunnel is equipped with its own burner, giving advanced temperature control for a wide variety of products.

This day, with the steam tunnel inactive, baking proceeded at 460°F for at 8½ minutes. “We can go from go from eight to 10 minutes on baking and 460 to 510°F in temperature,” Mr. McCarty noted.

Baked buns exit the oven to be released from their pans by the Stewart Systems depanner. Buns travel on an inclined conveyor and enter at the top of the G&F Systems spiral cooler. This loading method optimizes the cooler.

“Heat rises,” Mr. Chan reasoned, “so you want to cool most effectively by putting your warmest product at the top, not the bottom. You don’t often see spiral coolers run downwards at other bakeries.”

The depanner releases empty pans into the pan recycling system. A Stewart Systems vertical-edge pan cooler accepts the hot pans, carrying them on edge, rather than flat. “This is a more efficient way to cool pans and involves less maintenance than other cooling methods,” Mr. Sanchez said.

Pan handling at Mile Hi also involves a pair of Stewart Systems stacker/unstacker units that pull off or put on pans according to the production schedule. The vertical-edge pan cooler delivers pans upside down to these units. The company chose pan designs that enable the rims, not the cups, to bear the full weight of the pan.

Achieving packaging flexibility

All buns leaving the spiral cooler pass through a Sightline optical inspection system. Each is inspected and graded according to nearly a dozen parameters. A row of air jets mounted above the conveyor will knock out any nonstandard buns as they pass. Mile Hi used optical scanning at its old bakery, but this system is far advanced, especially in its data capabilities. Graphs displayed by the control terminal show how products are trending.

All buns go through a Mettler Toledo metal detector ahead of the packaging machines.

Packaging operations reflect the bakery’s flexibility as well as its computerized operation. “In the packaging area, we count, slice, pack, stack, wrap and introduce to the freezer all automatically,” Mr. Chan said. “This keeps a solid FIFO system going.” Additionally, packaging is capable of both bag and bulk packs and two different styles of shipping containers: corrugated trays and plastic baskets.

“With the two Stewart Systems Pillo-Pak bulk packers, which assemble 20 to 30 buns per package, we can do a dual center seal, with options for perforation and skip-seal — a transverse seal that divides each package into quadrants,” Mr. Sanchez explained. The bakery’s two UBE horizontal baggers provide the capacity for 8-, 10- and 12-count bags.

Two Stewart Systems Pak-Stak P-1000 tray loaders — one brand new and the other repurposed from the old bakery — load the bulk-wrapped buns into plastic delivery trays, conveyed automatically on an overhead line from the Newsmith tray washer. Because the washer uses cold water and recycles half of it, this system accounts for 20% of all Mile Hi Bakery’s energy savings.

Some customers prefer their buns delivered in corrugated trays, and an IPak TFD 350 system erects these shallow trays. The filled corrugated trays are banded in stacks of five each. The project team had FleetwoodGoldCoWyard reconfigure a palletizer for bear cases to accommodate bun trays.

The palletizer assembles four stacks onto slave pallets made of 100% recycled plastic. The grouped stacks move into an M.J. Maillis stretchwrapper that stabilizes the load.

When the system signals availability of a wrapped pallet ready for the freezer, it activates a short bridge-like conveyor between the stretchwrapper and the freezer. The system’s cartridge extends to pick up the loaded pallet and carries it through an automated door to take it into the freezer. When idle, the bridge retracts to allow foot and lift truck traffic.

Teaming up for success

“Another of the principles of LEED is that you use what you already have,” Mr. Sanchez observed. “And the former keg room is now our freezer.” The large 7,800-sq-ft freezer, held at -10°F, has a chilled entry foyer. The freezer’s double-deck, gravity-flow racks hold a total of 650 pallets when completely full.

Five loading doors comprise the cold dock and allow trailer loads to be staged according to customer needs. Mr. Borowski pointed out that the distribution division’s full yard is located right at the back of the bakery.

Empty trays returning to the bakery are segregated from the production area. The Stewart Systems debris removal system denests the stacked trays and puts them through an S-shaped double-dump line. No manual handling of stacked trays, dirty or clean, is required. Because Mile Hi uses several tray colors and sizes, the denesting system also sorts the trays, so only one style at a time goes through the washer. When the wrong color or shape passes a sensor, it trips a reject cylinder that pushes the tray to another stacker to be reinserted into the system when needed.

In all, the design and implementation of Mile Hi’s new bakery required teamwork throughout the organization. Such cooperative efforts represent a core value at the company.