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Cranberry Processing

December 23, 2005

Vincent recently participated in testing at a cranberry processing plant. Many years ago we had sold screw presses for juicing cranberries, and it was interesting to see how the industry has evolved.

At the plant where we were, the cranberry juice was recovered in an extractor, without the use of the traditional screw press.

The plant can hold 1.5 million barrels of cranberries in frozen storage, and can process 900,000 barrels a year (100 pounds per barrel). Thus the plant runs year round. Bins of frozen berries are dumped into a sizer that blows out the trash, drops the unders, and screens out the overs. Then the berries are pneumatically conveyed to where they are separated from the air stream and dropped into Urschel slicers. This produces pieces much like sliced olives in a salad, about 1/16" thick. Then they are fed into the juice extractor.

The extractor looks like a 4' diameter screw conveyor in a 30' long trough. The screw rotates slowly 120 ° in the forward direction and then backs up 90°, then forward again, all at low rpm. The action, controlled by a VFD, is extremely smooth. The screw is inclined about 10°, and the flights of the screw are covered with slots that are smaller than the cranberry slices. The result is that water put in at the high end flows down, going through the cranberries that are being screwed uphill. Thus, the machine is a true counterflow diffuser, without need for separation between various stages.

The berries are 8° Bx to start, and they are under 0.5 o Bx at the discharge of the extractor.

The sliced berries from the discharge of the extractor were landspread ten years ago. Instead, now they are sent to an infuser, where they are made into "sweet & dry". This is a diffuser running backwards. Sugar solution with flavoring concentrate is added to the slices. Cranberry, orange, cherry, and other flavors can be used.

The pieces are then dried in Sanvik bakery-style band dryers, to make Craisins and similar products. The markets in snack foods and breakfast cereals have shown excellent growth. The two leading cranberry processors, Ocean Spray and Decas, have distinct methods of diffusing cranberries, each covered by its own process patent.

Issue 168