©Cahners Publishing Company, reprinted from Packaging Digest
Protecting primary packages from condensation and moisture damage when shipping product halfway across the globe is no easy feat. Pineapple canned at its source in the Philippines by San Francisco based Del Monte Foods underwent lengthy, month-long voyages through extreme climates from tropical to arctic before reaching U.S. and other destinations, mostly without incident. But in 1993 Mother Nature threw Del Monte a curve ball in the form of altered weather patterns, and cans inside the overseas cargo containers began sustaining extensive moisture damage, despite being packed in corrugated containers, stacked on pallets and unitized with stretch wrap.
“We found heavy amounts of rust on the cans, and discoloration of the paper labels,” says Terry Koberstein, principal packaging technologist for Del Monte. “It was worse than anything we had seen before.”
Del Monte quickly took steps to contain the damage. “We set up inspection procedures at tremendous cost to ensure that our customers were getting the highest quality product,” recalls John Pearson, Del Monte’s director of technical services and development, and head of the packaging team that eventually solved the problem.
“Since we responded immediately after the problem was detected, only a few customers witnessed it,” he says. After experimenting with different solutions in simulated weather conditions in high-tech, climate-controlled rooms at its Walnut Creek, Calif., R&D facility, the company found the most success with United Desiccants’ Container Dri® desiccant pouch.
The desiccant was developed specifically to combat condensation during long-haul transport via sea, air or land.
The 500-g pouches, made from a clay-based desiccant, absorb up to half their weight in moisture, unlike silica-gel desiccants that adsorb moisture, or attract moisture only to the surface of the desiccant. While silica-gel desiccants technically would have worked, the sheer quantities that would be required were neither practical nor cost-effective. Container Dri activates whenever the dew point is reached and condensation starts to form inside the cargo container. The dew point itself varies depending on a number of factors including temperature and humidity. When product reaches its destination, the pouches are removed and discarded. “You could feel the difference between Container Dri and silica gel,” says Janice Ma, a Del Monte researcher involved in the project. “When you picked up the Container Dri, it was heavy, soaked with water, while the silica gel hadn’t absorbed nearly as much moisture.”
The 10×5 3/4×1-in. pouches are either laid on the floor of cargo containers or are taped at intervals atop pallet loads as they are loaded inside. Seventeen pallets, with 100 cases per pallet, are loaded into each sealed container; the same quantity of desiccant is used each time. Cargo containers are loaded in Bugo (Philippines), shipped to Kaohsiung, Taiwan, for transfer to a larger vessel (after storage time on the docks). Product enters the U.S. via one of three ports: Seattle, Oakland or Los Angeles.
Del Monte reports an extremely high success rate in eliminating moisture damage, resulting in savings that run into the millions of dollars, primarily from recovered product and lower insurance premiums. Inspections are now limited to an occasional monitoring of humidity via probes placed in an occasional cargo container. Although the company began using the desiccant in April ’94, “We waited a full year before calling the program a success,” says Koberstein, “to make sure we went through every season and every factor that could occur in a 12-month cycle. Since using Container Dri we’ve had a 100-percent success rate, zero failures and no damage claims. “