Food processors have operated under food safety mandates for centuries, so the idea that they must have a focus on safety is not new. In 2011, however, the Food Safety Modernization Act (FSMA) was signed into law, which shifted the U.S. Food and Drug Administration's focus from a reactionary role (one after an outbreak of foodborne illness) to a preventive focus.

Among its many requirements, the FSMA specifies that process owners develop and implement either a hazard analysis and critical control point (HACCP) plan or a hazard analysis and risk-based preventive controls (HARPC) plan for their operation. According to the FDA, “HACCP is a management system in which food safety is addressed through the analysis and control of biological, chemical and physical hazards from raw material production, procurement and handling, to manufacturing, distribution and consumption of the finished product.”[1] Hazard analysis and risk-based preventive controls, or HARPC, is a successor to the HACCP food safety system.[2]

As changes are made or facilities are updated, HACCP/HARPC plans need to be reviewed and updated. So too should the design of the filtration system, which stands at the center of food safety.

This article will demonstrate some filtration system lessons learned by food processors. It is hoped these examples can illustrate the key role that filtration plays in food safety.

Putting Filtration to Work

Case in Point. When a large commercial dairy cooperative located in California’s Central Valley decided to expand its operation, the management team needed help designing a culinary steam system that would protect the equipment and processes. The expansion included an aggressive timeline, a limited budget and the challenge of meeting regulatory compliance standards for food production safety in California.

The dairy contacted a filtration company, which shared its food and beverage industry experience while working with the dairy cooperative’s engineering firm and a local equipment provider. Together, the team designed and installed a culinary steam system that utilized a combination of stainless-steel filter housings and elements that met the regulatory requirements for the process.

If your facility needs a similar system, when examining your processes and facility layout, pay attention to two important areas for filtration:

• Where contaminants are first generated or introduced.
• Where the process has further exposures to risk.

Start by addressing utility sources, and where liquid, steam and gases such as nitrogen and compressed air are generated or bulk-stored in the facility. These areas are prime locations for oil, moisture, debris and bacteria — more so if the facility’s air or water are pulled from sources of low or unknown quality.

These filter elements are designed for liquid applications. Photo courtesy of Donaldson Process Filtration

Prefiltration

Plan to prefilter at the sources of contaminants. Consider the efficiency of the filter elements when capturing large particles or a high volume of contaminants. For industrial applications such as washing, cleaning and sterilizing equipment, the size of filter elements can make a difference. Prefiltration upstream will help minimize replacement costs and downtime by protecting the most expensive fine-fiber filters on the process line. Well or river water carrying a lot of debris may require different types of prefilters. Polluted air may need more than one compressed air prefilter, especially when used in food-contact applications.

Case in Point. For a filtration project with British cider-producer Thatchers Cider, the plant management team wanted to find new applications for well water that was sourced from its on-site borehole. After looking at the options, the cidermaker decided to install a two-stage filtration system to purify the well water. This solution allowed the cider maker to use the purified well water to clean machines and wash equipment in the plant.

Compliance with the federal Food Safety Modernization Act includes the development and implementation of a HACCP or HARPC plan. As changes or updates occur, those plans need to be reviewed along with the design of the filtration system, which stands at the center of food safety. Photo courtesy of Donaldson Process Filtration

Beyond Prefiltration

In some cases, contamination cannot be prevented at its source. After prefiltration, you need to identify critical control points on the process line: wherever there is an opportunity for new contamination, or where ingression would be irreversible. At these points, you will want to use sterile-grade elements; typically, 0.2 microns or smaller are recommended. Some of the critical control points include:

• Mixing and storage tanks.
• Intermediate steps and ingredients.
• Final processing and packaging.

Mixing and Storage Tanks. Undesired bacteria easily can breed in these locations, and oxygen also may spoil some products. Inert nitrogen makes a good tank buffer before ingredients are added. First, though, be sure to filter the nitrogen to remove potential impurities from tanks, compressors and hoses.

Intermediate Steps and Ingredients. Wherever there is a new step or ingredient introduced in the process, there is an opportunity for contamination. For example, when additives are included for flavoring or seasoning, preservatives or emulsifiers, there is a new opportunity for contamination, and a filtration step is needed. In soda, it is the addition of carbon dioxide that can add risk. Consider adding filters for each new ingredient as well as for any new gas, steam or air process involved.

Final Processing and Packaging. To remove any surviving contamination at the end of production, plan a final filter process step. In water bottling, for example, a final membrane filter is recommended. In addition, the packaging itself can introduce impurities. Wraps and seals that come into contact with the food or beverage should be blasted with culinary steam or compressed air to kill any microbes picked up in transport or storage.

Case in Point. On one installation, a filtration system manufacturer has multiple compressed air filtration lines installed in several facilities of a major U.S. bottled water company. The lines supply purified process air to the polyethylene terephthalate (PET) bottle blowing machines. By injecting sterile, compressed air into a shell of PET, it expands into a mold of the bottle shape, and the compressed air cleans the bottles before they are filled with water.

Equipment Considerations

After reviewing your process line and identifying key locations for filters to reduce the chance of contamination, consider the quality of your equipment and your choice of elements. Watch for aging or malfunctioning components such as air compressors, which are a frequent source of oil leaks. Pipes and housings are other potential sources of contaminants as they can flake or develop crevices that trap decay.

Stainless steel systems are specified in most standards and guidelines, but if components are not 3-A certified, they can still have hidden risks. They include:

• Poor welds with rough areas. (There should be no corners or crevices and there should be sloped surfaces to promote complete drainage.)
• An electro-polished surface to a minimum of a Ra32 surface (consistent satin finish).
• Pipe joints with a flange or national pipe thread (NPT) connection instead of a sanitary connection such as sanitary clamps fittings.

Incorporating these specifications allows a pressure vessel (filter housing) to be cleanable during clean-in-place (CIP) and sterilization-in-place (SIP) protocols.

When selecting equipment for food processing, do not confuse a manufacturer’s “3-A compliant” claim with “3-A certified.” To be considered certified, the equipment must be verified by a third-party Certified Conformance Evaluator (CCE) to have a sanitary design; this design reduces the number of harbor points where bacteria can gather and multiply in a process line. Interior housing surfaces shall not have any flat surfaces with corners or crevices and should have sloped surfaces to promote complete drainage. Most housings will have domed construction with curved tangency points in the top (vent) area and bottom (drain) area.

Filter ratings can be a source of some confusion as well. A micron rating is the particle size that a filter is designed to catch. Efficiency is the percentage of capture in that micron range. Both factors are needed to select the elements. Not all particles are of equal size and shape, so it is wise to test out and refine the type of filter elements that will be most effective for your application.

Once you have reviewed the ratings and checked for certification, below are other considerations for your filter media:

• Depth-loading capacity (retention).
• The number of sterilization cycles the element can safely tolerate.
• How often the element will need changing (filter life).
• Flow rates, which drive energy costs.

All of these performance factors can contribute to your total cost of ownership. For instance, a pleated liquid cartridge filter may last longer and provide savings when compared with a common melt-blown filter that requires multiple change-outs.

Reliable filtration is all about using a filter with the appropriate efficiency and micron size in the right location. Reputable filter providers often have helpful materials that include regulatory best practices, a recommended filter-and-element replacement schedule, and experience with your processes. PC