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Applications. Water is universal throughout food processing, both as an ingredient and as a power source. It is used to wash raw produce, rehydrate concentrations, cook ingredients, heat steam boilers, drive product recovery systems, and sterilize equipment and containers, among other applications.
Risks. Incoming water lines can carry harmful corrosion and debris. Sediment can build up on boiler equipment and interfere with efficient heat exchange or end up in the final product. If water is used as an ingredient, it must be dechlorinated with activated carbon, which can then be a food source for any remaining bacteria. Wash water is a cross-contamination risk that can carry microorganisms onto downstream surfaces.
Best practices. Pre-filter the water line coming into your process using nominal polypropylene depth filters of 10 microns. Higher levels of suspended solids may require a series of 50-, 20-, or 10-micron liquid pre-filters. Analyze water quality and adjust filtration for seasonal changes to help ensure product consistency. A 10-micron element provides an acceptable level of industrial water for non-food contact, steam-in-place (SIP), and clean-in-place (CIP) processes. Downstream in the process, install final filters on water lines dedicated to your washing, cooking, blending, or injection stations. Bacterial-retentive sterile filters of 0.2 microns are recommended. In many cases, microfilters of this grade can be used to produce pasteurized-equivalent water.
Applications. Large volumes of steam are required in food processing as a heat source for cooking and as a cleaning agent. Steam is either culinary grade—fit for direct injection into food or to sterilize food contact surfaces—or utility steam, suitable for efficient indirect heating.
Risks. Steam temperatures resist microbial growth, but boiler deposits, debris, and rust are a common hazard. Lengthy steam lines are generally made of carbon or galvanized steel, which can corrode quickly under constant condensation and heat. These byproducts threaten both product and equipment. Stainless steel will not rust when exposed to water, but it will when exposed to rust shed by nearby carbon steel. Corrosion can also plug the spray balls on steam injectors and cross-contaminate stainless steel.
Best practices. On each steam line into your process, place an entrainment separator—a pre-filter that coalesces bulk moisture out of the system and drains it away. The relatively dry steam remaining transfers energy more efficiently and reduces the amount of boiler water entering your product. Each pressure reduction valve should also be protected with an entrainment separator. Place a final steam filter at each point of use. For direct steam injection or CIP/SIP use, culinary-grade steam is required by 3-A Sanitary Standards. Culinary grade is defined as steam filtered to remove 95 percent of particles 2 microns and larger.
General Principles for All Utility Filtration
There are general principles that apply to all utility filtration—steam, water, and air or gases—regardless of the process or application. Remember the following tips as you plan your system.
Redundancy. Similar to accident prevention on the road, filtration at multiple points in a process is far more effective than relying on one filter alone. Pre-filtration upstream can help minimize replacement costs and downtime by helping to protect more expensive microfilters on your process line.
Placement. As stated in the outset, place final filters as close as possible to point of use. If there are 1,000 feet of piping between a final filter placed in a utility room and the food contact point, that is 1,000 feet of line that could shed condensation, oil, debris, and microbes into the product.
Filter media. Traditional melt-blown filters are not always less expensive in the long run. Newer pleated cartridge filters have roughly 12 times the surface area and depth-loading capacity of a melt-blown filter. That added surface area supports a long filter life.