Proving that bigger is not always better, a small liquid nitrogen immersion freezer turned out to be the perfect solution for Wampler Foods Inc. when it decided to improve the efficiency of its lower-volume, diced poultry freezing operation in Franconia, PA.

Installed in January, the Air Products Cryo-Quick® RH Immersion freezer increased hourly production rates, reduced freezing costs, and maintained consistent product shape, according to Eric Patton, director of further processing.

"We were limited by an outdated line that allowed us to process only 1,600 pounds an hour," notes Patton. "While we were getting acceptable quality, we were not always getting properly shaped cubes using a carbon dioxide [CO₂] tunnel freezer."

Wampler investigated freezing options, ruling out mechanical freezing because product volume was too low. "We evaluated immersion freezing against CO₂," adds Patton. "Price was one factor and we needed to find out about finished product quality with immersion freezing. Successful shelf-life tests here and at Air Products' Allentown, PA, food laboratory convinced us."

Wampler Foods' smaller RH unit is only 10 feet, 9 inches long by 44 inches wide and has a small 28 inch belt width. It is housed in a reconfigured chilled processing room measuring 26 by 48 feet The smaller freezers are capable of efficiently processing as little as 1,000 pounds of product per hour. They incorporate all of the benefits of Air Products' larger immersion freezers but with half the belt width.

Product is immersed in a bath of liquid nitrogen at -320° F and instantaneously crust-frozen to prevent clumping and reduce dehydration. Immersion times are controlled by changing the amount of belt passing through the nitrogen or by changing belt speed. Wampler's system uses PLCs that keep liquid nitrogen at a constant level while regulating nitrogen consumption and other process parameters to maintain product quality and system efficiency.

According to Patton, dicing output has increased by more than 50 percent, with maximum throughput based on other operations such as packaging. "The freezer is not the control point," he notes. "Using the new freezing process, we have also improved the dimensional quality of our diced products, usually 3/8-inch cubes. Although it is too early to tell exact savings, it appears we have reduced our freezing costs versus CO₂. Those costs include liquid nitrogen, on-site tank rental and the freezer itself. We have now standardized on using nitrogen."

Air Products and Chemicals Inc., 7201 Hamilton Blvd., Allentown, PA 18195-1501. Tel.: (610) 481-4911 Website: www.apci.com