- THE MAGAZINE
The name Roundy’s Supermarkets is well known throughout Wisconsin, Minnesota and Illinois. The Milwaukee, Wis.-based company’s 160 retail grocery stores and 88 pharmacies, operating under the names Pick ’n Save, Rainbow, Copps, Metro Market and Mariano’s, employ more than 18,000 workers with annual retail sales topping $4 billion.
Known primarily for its freshly prepared foods and broad deli selection, Roundy’s food production facility located in Kenosha, Wis., is central to the chain’s operation. This 120,000-square-foot plant is a hybrid facility, comprised of multiple separate food processing capabilities under one roof encompassing meat processing, dairy foods manufacturing, baked goods production, bottling of prepared drinks and preparation of a wide selection of fresh deli foods. Selling a high volume of freshly-prepared soups and salads, its store delis require constant preparation of pasta and potatoes as key ingredients.
Need for a better cooking/cooling process
Since Roundy’s first began preparing fresh soups and salads in 2007, it has relied on a chain-driven, semi-continuous conveyor batch process system for cooking and cooling its pasta and potatoes. In this process, raw diced, cubed and sliced potatoes and dry pasta was loaded by weight into a continuous series of baskets connected by a chain conveyor that pulled through a cooking chamber where steam was used to penetrate and cook the product. Downstream within the chamber, a cooling zone utilizing chilled water sprayed onto the potatoes or pasta to reduce the temperature and stop the cooking process.
For many years, water-spray conveyor systems were the standard for cooking and cooling food products such as pasta and potatoes, but these systems have their drawbacks.
For example, cookers and coolers are only as good as their ability to precisely control the product’s time and temperature parameters throughout the processes. Conveyor-based spray systems are prone to variable cooking and cooling rates. Lacking uniform water spray coverage of the product and adequate agitation to keep pasta and vegetables separated during the cook and chill cycles allows for products to be unevenly cooked.
“With our potatoes, the wedges and slices did not cook well,” says Mario Jedwabnik, vice president of manufactured foods at Roundy’s. “They would stack up and the steam penetration was insufficient to cook through the layers, so some potatoes were undercooked. Cooling them down was another problem. We could not get enough water on the potatoes to cool them evenly.”
“But, the pasta was a nightmare for us,” adds Jedwabnik. “Our conveyor baskets were 16 inches wide x 36 inches long, and the pasta tended to compact into them like a paste during the cooking and cooling processes. There was not enough circulation of water through the baskets to keep the pasta separated.”
There are many different types of pasta, each requiring varied cooking times. Pasta needs to be cooled very rapidly to stop the cooking process. This is particularly important in keeping the long pastas like fettuccine, linguine, tagliatelle and spaghetti from sticking together during cooking and cooling. The sticking develops clumps of pasta, which need to be removed, thus increasing waste. Hence, the long pastas run a higher risk of being clumped together and lost in production processes like conveyor batch systems.
Roundy’s was also plagued with excessive downtime, amounting to 30% of available production time, with such problems as conveyor chain breaks and baskets becoming separated from the chain and jamming inside the cooking and cooling chambers. These required the unit to be cooled down, taken apart, repaired, re-welded, cleaned and restarted.
Changeover times between potato cuts or pasta varieties took about 60 minutes, primarily to allow the cook and cool cycles to complete. Changeovers between potatoes and pasta, which required cleaning the system, would take 2.5 hours to perform.
“We ran the conveyor batch system for about 2.5 years, until 2011,” says Jedwabnik. “We were processing 600-700 pounds of potatoes per hour and 1,000 pounds of pasta per hour. But, this was not enough to keep up with the demand from our store delis.”
Roundy’s researched a number of different systems that could handle their potato and pasta throughput needs. One was a new continuous rotary cooking and cooling design manufactured by Lyco Manufacturing, Columbus, Wis.
“We visited the Lyco plant in Columbus, Wis.,” says Jedwabnik. “We discussed options with their engineers, and subsequently tested our potato and pasta products through Lyco’s cooking and cooling equipment at their on-site test lab. The speed of processing and the quality of the finished product impressed us. We could see what the finished product was going to look like.”
The switch to continuous-flow rotary processing
In March 2011, Roundy’s selected a Lyco Clean-Flow continuous-flow cooker and cooler system to process its potatoes and pasta. The 7-foot long, 40-inch diameter Clean-Flow cooker was backed up by a 4-foot long, 40-inch Clean-Flow cooler, capable of moving 2,000 pounds of pasta or potatoes through the system per hour. This resulted in a 300% increase in potato throughput and a 100% throughput increase in pasta.
The new continuous-process cooker/cooler utilizes an auger to control product retention time while a water injection system called Hydro-Flow agitates the product and holds it in suspension through an enclosed water-filled screen. Considered the industry standard for continuous-process cook and chill methods, this latest design in continuous cooker/coolers has significantly improved the processing of pasta and vegetables, ensuring more uniform processes and the ability to handle higher throughputs.
The continuous-flow cooking/cooling system that Roundy’s adopted utilizes two completely enclosed continuous Clean-Flow units—one for cooking and one for cooling directly following in sequence. The machines have internal augers to control dwell time in a wedge wire basket. The auger flights do not drag the product through the cooker and cooler system. Rather, pasta and potatoes are carefully agitated while suspended in water, as they advance through the auger and basket assembly. Damage to the potatoes and fragile pasta products is a fraction of 1%.
Once product passes through the cooker machine in a first-in/first-out sequence, the potatoes or pasta gently deposit into the following cooler to be chilled to its programmed temperature. The product then discharges out of the system and is evenly cooked and cooled to specification. The cooler runs at 50-60°F, which stops the potatoes or pasta from further cooking. This improves the product consistency and gives a better quality product.
Clean-Flow is designed to maximize up-time by minimizing cleanup turn-around time. Roundy’s cleanup time improved 300% from 2.5 hours with the old system to 45 minutes because the auger is totally exposed for cleaning. During cleanup, the screen releases from its fixed position and continually rotates 360 degrees around the auger, alternately exposing the interior and exterior of the screen to clean-in-place manifolds located in the cover of the machine. The auger can be rotated at the same time as the screen, again exposing all surfaces to the cleansing water sprays.
Streamlined process controls
Roundy’s continuous-process cooker/cooler is equipped with a programmable logic controller (PLC) that provides precise automated control of process functions, including recipe selection, achieving a totally consistent end process.
This control system minimizes the time required to perform complex tasks and increases efficiency in process operations. Consistent process parameters for time and temperature completely out-performs the batch method formally used by Roundy’s, achieving a much higher quality end product and faster ROI.
By early 2012, Roundy’s product demand for potatoes and pasta increased dramatically, exceeding capacity on its 12-month-old cooker/cooler system.
“We went back to Lyco’s engineering team to re-evaluate our needs,” says Jedwabnik. “We emerged with an upgraded Clean-Flow system capable of processing 3,000 pounds of potatoes per hour and 3,500 pounds of pasta, which is significantly more than our previous system.”
In fact, the new Clean-Flow cooker/cooler system can process more than 400% more potatoes per hour and more than 300% more pasta per hour compared to Roundy’s original conveyor batch system, with virtually zero product defect and near-zero downtime from malfunction.
“Aside from the sizable increase in throughput volume, the product coming out of the new Clean-Flow cooker/cooler is consistent,” says Jedwabnik. “We are very pleased with the system’s performance.”