To remove foreign materials and unwanted agglomerates from dry bulk ingredients, sifters can stand guard at multiple points within an automated bulk ingredient handling system.

“A sifter can be placed in the intake line between the truck and the silo, as a first control point to ensure that the received product is free of any foreign material as well as any lumps,” said Dominique Kull, manager, bakery supply systems, Buhler, Inc., Plymouth, MN. “Another possible location is in the pneumatic pipe before the receiving hopper, which ensures no foreign material is going into the mixer.”

The earlier that foreign material gets detected, the simpler it is to determine its source and reject accordingly. ”After all, the combination of sifting at the very beginning and the very end of the system ensures the highest possible control in regards to the food safety aspect,” Mr. Kull added.

Almost all bulk ingredients systems purchased today include sifters, said Bill Kearns, vice-president, engineering, The Fred D. Pfening Co., Columbus, OH. “In-line pressure or vacuum sifters are the easiest to include, but they bring a pressure drop that must be considered in designing the system,” he explained.

KB Systems, Inc., Bangor, PA, recommends sifters for all bulk handling systems to enhance food safety. Its inline centrifugal sifter features an easily accessible screen that may be removed with relatively little downtime. “In most cases, the customer would purchase a spare screen assembly for rapid swap-out,” said Michael Palmer, general manager, KB Systems. 

Forcing a dry ingredient through a sifter slows conveying rates, said Kevin Rohwer, vice-president, Contemar Silo Systems, Concord, ON, but this slowdown is not significant and is generally taken into consideration when designing the system. “Unfortunately, sifters can significantly increase the cost of a system, especially for smaller wholesale manufacturers who are looking at more entry-level systems,” he noted. “These days, food safety is paramount, and sifters are essentially a must for all bakeries.”