Food Engineering

Dryer Controls Multiple Products to 0.5% Moisture

March 27, 2003
When Cascade Fruit Company wanted to expand product capability and total capacity, it had one problem -- not enough space in its 23,000 sq.-ft. facility to place additional equipment. The company processes and dries a wide range of infused fruit products and vegetables. Various product sizes, moisture levels and drying parameters made The Dalles, OR, processor's dehydrating requirements difficult to meet.

"Flexibility was a major consideration when we needed to upgrade our drying process," says Ron Wherry, special projects manager at Cascade Fruit. "We had been using a tray and rack system located on a trailer adjacent to the plant."

After looking at several suppliers, Cascade decided to work with Wenger Manufacturing who customized its Series VII, two-pass dryer for the process.

Wenger incorporated sanitation features such as all stainless steel construction, minimal internal ledges, fans and heaters located outside of airflow plenums and full perimeter doors for easy access.

Cascade's main product is infused blueberries for overseas markets. "However, other targeted products include infused bananas, cherries, strawberries, cranberries and pineapple as well as a variety of dried vegetables," notes Wherry. "Each requires different drying parameters such as time, temperature and air flow."

Wenger not only customized the dryer but also helped Cascade develop drying curves for its products. Integral to product flexibility is the dryer's airflow patterns. "Other dryers we looked at were preset for one specific product and very difficult to change," Wherry said.

Balanced, heated airflow from either side of the dryer minimizes uneven drying. Adjustable plenums can also direct airflow top-to-bottom or bottom-to-top. Temperature and belt speeds are PLC monitored and controlled. Since the system is modular, each zone can be adjusted independently for precise product optimization.

Products enter the dryer via an oscillating belt feeder after being cleaned, infused, inspected and sprayed with oil and flavor. Product initially proceeds through the dryer on an upper belt then cascades to a lower belt, redistributing and reversing product direction.

"Quality improvements have been exceptional," adds Wherry. "Integrity of the finished blueberries is noticeably enhanced. There is also less clumping and improved drying consistency."

Wenger Manufacturing, Northpointe Circle I, Ste. 510, 7505 N.W. Tiffany Springs Pkwy, Kansas City, MO 64153 Tel.: (816) 891-9272 Circle 203