From century-old dairy plants in Vermont to pet food startups in California, food manufacturers of all sizes face growing regulation. Of immediate concern is the Food Safety Modernization Act (FSMA) of 2010. Under part of the law phasing in through 2018, most processors must have “hazard analysis and risk-based prevention controls (HARPC)” in place to protect against food-borne illnesses. The U.S. Food and Drug Administration (FDA) has new powers to inspect and fine businesses if controls are inadequate. In this environment, facilities that once counted on grandfather clauses to stay in operation may now be considering a major update.
In any food plant remodel, filtration must be a focal point. It is hard to overstate the importance of sterile liquids, steam and air in food safety. Water is often a universal ingredient and is commonly used to cook, and to sterilize equipment. Compressed air is used to mold bottles, fill packaging, and blanket product in tanks and on process lines. Ambient air is drawn in as product storage tanks empty. These elements are frequent carriers of dirt, particles, oil and microbes, and can transport them into food at multiple points in a process.
International industry groups such as 3-A Sanitary Standards Inc. (3-A SSI) and Safe and Quality Foods (SQF) have established accepted practices and standards to address these risks. It can take time to comply with all applicable guidelines. However, observing just three filtration principles can provide a big head start toward complying with the standards, whether a plant is doing a few improvements or a complete revamp.
1. Place filtration equipment at the right points in the food and beverage process.
Regardless of how simple or complex a food manufacturing process is, every process owner needs to identify two crucial points for filtration:
- Points where contamination is first generated or introduced
- Critical control points where contamination of the product or process is at high risk, or where there’s a “last chance” to remove it
Plants that use multiple ingredients, heat and air treatments, and packaging steps may require a more complex filtration system. But every plant has a common challenge: control incoming contaminants and critical control points.
Points of generation are often where a facility draws in air or water resources, or where steam is created. Plants in industrial areas may pull in dirty air from the surrounding environment, while rural facilities may have more concerns about water quality. As steam is generated in the boiler from the plant’s main water supply, contaminants in the water or boiler will be transported by the steam. Based on best practices outlined by organizations such as 3-A and SQF, a filter or series of filters will be necessary at these sources.
Even in a closed loop system, the process itself can introduce impurities. Common internal points of generation are:
Aging equipment. Prone to leaks and cracks. Air compressors can leak oil, or housings can develop crevices that trap decay.
Carbon steel or iron pipes.A major corrosion risk. 3-A SSI guidelines are unanimous in specifying stainless steel piping and housings for all food contact.
Residual food after cleaning. Potential harbor points for microbes. Even microscopic amounts can be a serious threat as they multiply and travel downstream.
It is an unrealistic goal to remove all contamination sources where they originate. For this reason, sanitary plant design also calls for filtration at critical control points. These are locations in the process where the greatest harm can occur, either because the product is exposed to excessive contaminant, or because ingression would take place too late to be reversed.
To manage critical control points, consider these recommendations:
Place vent filtration on storage tanks. Storage holding tanks are a potential breeding ground for bacteria. As workers draw out product such as syrup to sweeten soda, pressure needs to be equalized to prevent tank collapse. Yet exposure to ambient air can spoil the syrup by introducing harmful substances. Two recommended solutions are purifying the make-up air with a vent filter, and/or blanketing the product with an inert gas, such as nitrogen, that has been filtered.
Install final filtration close to end use. Consider filtration at the last possible processing step to remove surviving contamination, and to prevent the pickup of harmful bacteria just prior to packaging. In water bottling, for example, a final membrane filter will address remaining impurities. If carbonation is injected, the CO2 used should be filtered. Packaging itself can also be a risk. A yogurt maker that applies a foil seal, for example, should first blast the foil with culinary steam to kill microbes that may have collected on the foil during storage or production (Figure 1.)
Add protective prefiltration. Once control points are mapped out, it pays to think about adding lower-cost filters prior to point-of-use final filters. Though this may seem redundant, pre-filters aimed at capturing larger containments will increase the longevity of the more-expensive, small-particulate filters. Process owners who decide not to worry about incoming contamination and rely only on final filtering will expose their entire system to a barrage of contaminants, and overburden the final sterile filter. Prefiltration will help minimize replacement costs and downtime.
2. Identify correct filter technologies for food plant remodel.
Two areas of potential confusion about microfiltration exist: ratings and construction. Here are some facts for more-informed product selection:
Look beyond microns. Not all filters rated for the same micron size are equal. It is vital to consider not only the particulate size a filter is rated for, but also the efficiency at which it is able to capture the particulate. Efficiency is crucial in knowing how much contaminant the filter captures (percentage) at a given micron size and larger. When selecting a filter, it is also important to know if the filter is absolute or nominal. An absolute filter is comprised of higher quality filtration media that can provide an efficiency of 99.98 percent or greater at a specific micron rating. On the other hand, a nominal filter is a lower-quality filter that typically provides only 60 to 98 percent efficiency at that same micron level.
Without this information, it is impossible to select the right element for a specific demand. In fact, it can be dangerous. Whereas one filter may be only 85 percent efficient at 1 micron for final water filtration for lemonade, another 1-micron filter may deliver 99.99999 percent (7-log) efficiency. The reverse can also be true. A 10-micron filter at 5-log efficiency (99.999 percent) might be overkill for early stages of dirty-water processing, and may require frequent replacement (Figure 2).