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Protecting Product Purity

September 26, 2008

By Kent Potter
Bunting Magnetics Co.

Kent Potter

Foreign matter are dirty words in the food production industry. Meticulous detail must be maintained throughout production and preparation to avoid the inevitable media coverage that occurs with any tainted food product being publicly sold. To avoid the need for crisis management, or irreparable damage to your corporate brand, it is important to implement a Hazard Analysis and Critical Control Points (HACCP) process within your manufacturing environment.

HACCP is used to identify potential food-safety hazards, so that key actions can be taken to reduce the risk of the hazards being realized. This approach addresses physical, chemical, and biological hazards via prevention rather than relying on finished-product inspection.

The Food and Drug Administration and the United States Department of Agriculture use mandatory juice, seafood, meat, and poultry HACCP programs. The use of HACCP is currently voluntary in other food industries but really should be seen as a necessary precaution.

There are several considerations to make when protecting the purity of your product and the operating efficiency of your equipment. First, you must incorporate sanitary equipment design. The materials used for food-processing equipment should be easily cleanable. Surfaces deteriorate with age, and abrasions make cleaning more difficult. For cleaning and sanitation to be effective, all parts of the equipment should be readily accessible. Another way to improve equipment hygiene is to use antimicrobial coatings on equipment parts.

Materials that do not belong in food cause physical safety hazards. Rocks, metal, wood, and other objects are sometimes found in raw ingredients. Sources of foreign matter in raw food materials can include nails from pallets and boxes, ingested metal from animals, harvesting-machinery parts, veterinary instruments, caps, and lids.

Processors for dealing with this problem include separation equipment, such as air cleaners, magnets, screens, sieves, traps, metal detectors, and washers. Most grain processors use four screens to remove foreign materials.

There are certain criteria to understand prior to designing a complete and effective system. A review of your production process is the first step to take with examination of the key entry points for product including storage areas, different processing activities with equipment that could be damaged by foreign matter, and key departure points prior to packaging and shipping.

Next, you need to determine what type of equipment is needed. Based on the point of processing, magnetic metal separators are built around either cartridges or plate magnets. To choose between these two types of separators, you need to consider the characteristics of the materials you want to clean and the system through which you will be running them.

Cartridge-based separators, like grates and drawer magnets, are designed to handle vertical gravity flow and materials that flow easily and do not form clumps. Plate-based separators can be installed at angles or in pneumatic conveying lines. They are designed to handle materials that exhibit poor flow characteristics, tend to clump, or are coarse and highly abrasive. Self-cleaning and continuous-cleaning models are available to handle heavy contamination and inconvenient locations.

Furthermore, product densities, flow rates, operating temperatures, and the type of ferrous contaminants you encounter help determine the choice of magnet material. Ceramic magnets are well suited for typical tramp-iron separation. But if operating temperatures are high, then Alnico magnets should be used. If product densities and flow rates are high and your operation occasionally encounters weakly magnetic debris such as fines and even some grades of work-hardened stainless steel, then high-energy rare-earth magnets are an option.

Finally, a number of factors influence the construction standard that is needed. For example, if the material handled is powdered or granular and it must flow cleanly through the system, a powder-grade model is the right choice. If the ingredients or final products are intended for human consumption, then food- or sanitary-grade separators are required. Many companies claim their equipment is food grade or sanitary grade, but a plant operator should always ask to see the clean-up specification sheet and check certifications.

Overall, product purification is not an accident. A good plant has repetitive measures in place at raw-material entry, before each processing piece of equipment, before mixing, before packaging, and then after packaging before shipping out to the customer.

Kent Potter is the separation product manager for Bunting Magnetics Co. (Newton, KS) and has worked in sales and product development for more than 20 years. He is responsible for a product line that spans the chemical, food, pharmaceutical, plastic, recycling, textile, and wood industries.