Processed Air Ensures Food Quality

Compressed air and culinary steam are commonly used in the food industry in a variety of applications including controlling devices used in the processing operation (e.g., using compressed air to open/close a pneumatic valve), handling the product and or packaging (e.g., ingredients handling, product transfer, a drying operation), or coming into contact with a surface in direct contact with the product (e.g., clean in place, using culinary steam to sanitize a component of the processing system).

The presence of materials like water (in compressed air), particulate matter, compressor oils, or microbial contamination in the air or steam employed in these operations may lead to significant problems. Typical difficulties include the following:

• The presence of water in compressed air used to dry a product might damage a product, or the product may not meet quality assurance requirements;
• The presence of particulate matter in compressed air used for controlling a pneumatic valve could cause the premature failure of the system, leading to the need to stop the production line and lost product and/or production time; and
• The presence of particulate matter in the direct processing of a foodstuff might lead to an out-of specification product (e.g., taste, color, odor, or other quality assurance product issue may result) or to issues related to operational regulatory requirements.

To avoid any of the above situations, the process engineer must determine the characteristics of the air or steam required for each operation and develop the optimum methodology to obtain the gas in the most economical manner. In the same vein, the maintenance manager, facilities manager, and various engineering personnel must continually ensure that the compressed air and steam used in the facility meet the requirements of the manufacturing processes.

Applications for Clean in Place

Clean-in-place (CIP) procedures are commonly employed to ensure the appropriate level of hygiene in the pipes, vessels, fittings, and related components in food processing systems. These procedures are faster, more reliable, less expensive, and less likely to expose workers to chemical risk than the traditional approach of system disassembly for cleaning. The air and steam filters are integrated into an overall system for the CIP process with appropriate valves, drains, pumps, pressure gauges, pressure relief valves, and associated controls, typically on a CIP skid.

The precise configuration of the system, as well as the steam and air filtration requirements, are, of course, dependent on the nature of the process, the materials that are being processed, and the size of the vessels to be cleaned. Typically, steam flow rates as high as 1,000 lbs/hr at pressures as high as 60 psi are employed. Steam filters that will filter up to 3,000 lbs of steam per hour at pressures as high as 125 psi are available; these filters include traps that dispose of the condensate before it reaches the filter.

Removing Materials from Compressed Air

A number of techniques have been used to remove moisture, particulate matter, and oils from compressed air used in food processing activities. In many facilities, the air is simply compressed and then allowed to expand to remove moisture. While this pressure regulation removes some of the moisture, a considerable amount remains in the air, and this air is not sufficiently dry for most purposes. To remove additional moisture, separators, chemical dryers, refrigerators, filters, and desiccant dryers have been employed to obtain air with the appropriate dew point and moisture content.

Filter systems are employed to remove the deleterious substances from compressed air and steam and are included in accepted practices. For example, accepted practices that describe filtering systems for air under pressure in contact with milk, milk products, and product contact surfaces, as well as culinary steam, have been developed by 3-A Sanitary Standards Inc. in collaboration with the U.S. Public Health Service and the European Hygienic Engineering & Design Group.1-2