Production quality and uniformity in food processing and its subsequent packaging is closely related to good Quality Control (QC) during the manufacturing process. In order to achieve high quality merchandise with minimal production losses, good process control and monitoring is critical. This is true for production of both the food product itself, the packaging, and of course for putting the former inside the latter efficiently. Laboratory and on-line systems are capable of delivering solutions for QC monitoring, and in cases where extra information (related sometimes to product development, and not to QC) about the flow properties are unnecessary, an on-line option can be the most useful.
On-line systems often provide streamlined data, showing changes in more limited criteria for the product during the process. In this way corrective action can be quickly taken, minimising potential for waste and reprocessing. Laboratory instruments, designed for quick data collection (only a few seconds or minutes) and intuitive understanding of the data can also be useful in this respect where no proven on-line alternative exists. On-line monitoring of shear viscosity is widely accepted for many kinds of materials including for liquid foods, and molten polymer packaging. In-pipe or in-tank probes can closely monitor the shear viscosity of the material in-situ, allowing operators and engineers to take appropriate action to maintain the specifications of the food product. These probes can also be mounted at the die end of an extruder, to monitor the viscosity of molten polymer before the moulding of packaging. Post-extrusion, the quality of the packaging material can be monitored optically to detect, catalogue and notify when user defined flaws exist in the packaging material (eg fish eyes, pin-holes, dark/light spots etc). For filling a liquid food into a package (by pouring, squirting, spraying etc), extensional viscosity often dominates the process. Unfortunately, there is no proven on-line method for monitoring the extensional viscosity of foods as they are dispensed from above into their packaging. Fortunately a novel, simple and quick laboratory technique has been developed for exactly this purpose – measuring the relative impact of the extensional properties of a liquid. In this way the product and the packaging can be monitored online right through the process, until the product has safely been deposited in its packaging.
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