When you drive, you take multiple precautions to prevent accidents. You put your cellphone away, use turn signals, observe stop signs, and stay a safe distance from the car ahead of you. No single measure guarantees a safe ride, but each one lowers your risk.
It’s the same with safeguarding your process. Each contamination hazard that you can identify and address reduces your risk. This is why food processors are required to develop a Hazard Analysis and Critical Control Points (HACCP) plan under FDA’s Food Safety and Modernization Act (FSMA).
Why Attention Is Required
A leading contamination risk is the utilities: the compressed air or gases, water, and steam used to perform processing steps. They can introduce dirt and bacteria from the outside world or pick up metal debris and oil from plant equipment. Deposited into food or onto food contact surfaces in a warm, moist environment, minor microbe concentrations can rapidly multiply into harmful colonies downstream.
For this reason, it is essential to address filtering air, gases, water, and steam in an HACCP plan. Generally, there are three areas in every process that require attention to utility filtration.
- Where contaminants could first be generated or introduced. This is usually in utility rooms where water, steam, and compressed air or inert gases are generated or stored. Pre-filtration here with larger micron-size elements that are designed to filter coarser particles can lessen wear and tear on downstream microfilters.
- Where the process or product has direct exposure. These are points of use where utilities come into direct contact with the product or food contact surfaces after traveling through equipment. Filters rated for removing microorganisms at a high capture efficiency should be placed as close as possible to each point of use.
- Where there is a last chance to prevent irreversible damage. This is at the end of a process, before product packaging. In some cases, such as water bottling, final membrane filtration is recommended. Whenever water, steam, or compressed air are used to blow-mold, clean bottles, or open bags, filter those utilities just before the application.
Unique Contamination Hazards of Each Utility
Each utility has unique properties and risks for contamination. Specific filters are designed for each challenge. Effective, cost-efficient filtration is all about placing the right elements and micron sizes in the right locations. The following are examples of applications, their associated risks, and best practices to consider.
Air and Gas
Applications. Gases used in food processing include pure oxygen, carbon dioxide, nitrogen, and most commonly, compressed air. Air moves ingredients, texturizes food, dries sterilized equipment, and forms containers. In storage tanks, compressed air or nitrogen are often injected as protective blankets around product.
Risks. Gas tanks and air compressors can be breeding grounds for microorganisms. As they draw in ambient air, compressors concentrate any bacteria present in that air volume. As compressed air cools, condensation creates the moist environment microbes need to multiply and equipment lubricants provide the food. The end result can be contamination and a permanent biofilm deposited in downstream piping. If you use inert gases such as nitrogen or carbon dioxide—even if supply tanks come from a vendor—changing tanks can expose open lines to airborne contaminants.
Best practices. Keeping air dry and oil-free helps keep it sterile. This can be achieved with a series of filters just after the compressor consisting of a cyclone separator to spin out bulk liquid, one or more 1- to 5-micron coalescing pre-filters to catch oil aerosols, and an adsorption air dryer to remove remaining vapors. At each point of use on air or gas downstream, place an absolute rated 0.2-micron final filter on injection equipment.