The butternut squash processing line is served by the makeup air unit equipped with UVC light.
Maintaining a clean indoor environment — whether to satisfy HACCP (Hazard Analysis and Critical Control Point) guidelines and/or to optimize product shelf life — is a concern of every produce grower and packer. John B. Martin and Sons Farms Inc. (Brockport, N.Y.) is no exception.

“We wanted to find a way to reduce mold counts in the room where we process butternut squash, but our facility did not lend itself to a true clean room environment,” said Peter Martin, production manager for Martin Farms. “Instead, we have had excellent success using a surprisingly simple solution: We pressurized the space and installed ultraviolet-C (UVC) lights manufactured by Steril-Aire Inc. (Cerritos, Calif.) to function as an air-cleaning mechanism. Our mold counts have dropped dramatically, our air quality has improved, and our shelf life has increased dramatically as a result.”

Before arriving at this solution, Martin Farms was experiencing high mold and yeast counts based on weekly product sampling performed by Primus Labs as part of the company HACCP program. Yeast occurs naturally in the squash itself but can multiply to undesirable levels if ambient conditions allow.

High mold and yeast counts from puree sample tests were confirmed when a technical consultant, FP Technologies Inc. (North Tonawanda, N.Y.), performed both air sampling and swipe (surface) sampling in the process area. Both types of samples showed very high counts of airborne and surface mold spores and yeast — about 20,000-plus colony-forming units per cubic meter of air.

“We suspected the cause to be cross-contamination from the far end of the building, where we produce raw cabbage product,” said Martin.

Working with FP Technologies, Martin learned of a new generation of devices that use UVC energy to eradicate both surface and airborne mold and bacterial contamination. The UVC wavelength targets the DNA of microorganisms, causing cell death or making replication impossible. The new-generation devices are designed to produce optimum energy output in environments with cold and moving air, making them ideally suited for food and beverage processing lines, cold storage areas, air conditioning systems and similar applications.

The main component of the new system is a 3,000-cfm makeup air unit that serves to pressurize the 800-square-foot room where butternut squash is prepped for retail distribution. Two UVC light fixtures are installed inside the air-handling unit.

Air-Handling Solution

The main component of the new system is a 3,000-cfm makeup air unit that pressurizes the 800-square-foot room where butternut squash is peeled, deseeded, cubed or halved, and tray-wrapped in preparation for retail distribution. Two commercial UVC light fixtures with 24-inch-long tubes are installed inside this air-handling unit.

The lights operate round-the-clock to eradicate airborne microbes that may pass through the system. The UVC energy emitted by the lights provides safe, continuous, nonchemical cleaning, keeping the inside air fresh while preventing cross-contamination.

Martin Farms operates this line on a seasonal basis from September to Easter. They are now in their third year with the UVC lights.

“During the production season, we run the lights 24 hours a day; based on that schedule, we get two seasons’ use from the lights. When we replaced the emitter tubes after the second season, it was as easy as changing light bulbs. The devices have not required any other maintenance,” said Martin.

Since the system started operating, FP Technologies has performed periodic air and surface sampling tests. Mold and yeast have dropped to a range of 1,800 to 2,200 colony-forming units — an approximate tenfold reduction. Tests on product samples reveal similar reductions.

Before Martin Farms instituted its HACCP program in this area of the facility, shelf life of the butternut squash was typically under one week. “We increased shelf life to 10 days once the HACCP program was in place,” said Martin. “After pressurizing the room and installing the UVC lights, we experienced another big improvement: We now average up to two weeks’ shelf life.”

The company is investigating additional uses for the product. Martin said he plans to install additional lights in the HVAC system opposite the cooling coils, to eliminate the organic buildup on coil surfaces. “UVC in this application will not only keep the air cleaner but will also improve the operating efficiency of the HVAC system,” noted Martin. He is evaluating UVC for upper-air application in cold storage areas and for use over conveyor lines.

“Our goal is to achieve the best possible product quality with the longest possible shelf life,” he concluded. “To attain this goal, we use a complex equation that includes not only UVC but also a good HACCP program, sound management practices in the plant, good refrigeration after processing, and much more. UVC has definitely improved the equation.”

For more information, contact Steril-Aire Inc. at 562-467-8484, 562-467-8481 (fax),, or FP Technologies Inc. can be reached at 716-692-8843 or 800-816-5594, 716-692-2035 (fax),, or

Publication date: 06/30/2003