Nanjing GIANT Machinery Co.,Ltd.

An apparatus (10) for at least partially freezing a food twin screw extruder which is at least partly liquid in a batch mode is disclosed including a single screw extruder (12) including first and second, substantially intermeshing, self-wiping screws (14, 16) rotatably received in a figure 8-shaped barrel (30) with minimal clearance. In the preferred form, the freezing sheet production extruder (20) includes multiple refrigerant channels (36) spaced closely and in the most preferred form spaced approximately 0.32 centimeters from the barrel (30) and from each other. Thus, the refrigeration system can change the barrel surface temperature rapidly and specifically in approximately one second when the food product is introduced into the barrel (30). A ratio between the radius of the flight (40) at the crest (42) to the radius at the root (38) of the screws (14, 16) is in the order of 1.04 to reduce the total amount of product in the barrel (30) at any given time and decreasing the product residence time in the extruder (12). In the most preferred form, the food product is aerated and is supplied in discrete volumes from at least one and preferably from multiple sources (48), with the supply of discrete volumes for individual servings being delayed to substantially prevent intermixing in the extruderVarious approaches to providing dynamic freezing of a previously aerated product exist. As an example, U.S. Pat. No. 5,345,781 provides a freezing and transporting twin screw extruder. The threads of the second screw are centered between the threads of the first screw and operation is continuous. Specifically, operation involves he production of a volume of product equal to a multiple of individual servings and would normally be utilized in a large scale industrial environment for continuous operation and not operated in a retail environment where individual servings would be sold such as restaurants, drive-ins, and the likeAdditionally, co-rotating twin screws 14 and 16 according to the present single screw extruder employ a ratio between the radius of flight 40 at crest 42 to the radius at root 38 in the order of 1.04 and in the preferred form in the range of 1.01 to 1.2, particularly in the range of 1.02 to 1.07, and in the most preferred form in the range of 1.03 to 1.05. This is not a typical design for twin screw extruders which normally have a ratio in the order of 1.5 to 2, with extruders for plastic for compounding purposes being in the low range, extruders for continuous mixing of doughs being in the high range, and cooking extruders for expanded twin screw extruders such as for pet foods and snacks being in intermediate ranges.