Photo Courtesy of Corrigan Mist

The technology for keeping produce moist and fresh has come a long way since the early days when retailers would put the greens to bed by covering them with moist burlap sacks.

Modern misting systems can boast incredible precision when directing moisture onto the produce, without causing dangerous wet spots on the floor or irritating spray on customers. Filters, UV light and ozone can all be incorporated to ensure the mist reaching the produce is pure and safe.

But faced with a dizzying array of available bells and whistles, the choice of which misting system to buy comes down to, most of all, the question of which one will avoid costly breakdowns.

“I would want the most reliable system I could get,” says Mike Corrigan, chief executive of Corrigan Mist, Gurnee, IL. “Anybody’s system will pay for itself pretty quickly, but if you have a system that breaks down for a day or two, you can lose a lot of produce.”

Continuous Misting

Miatech of Clackamas, OR, commissioned a study that showed vegetables literally shrink if they are not properly misted. The study (found on its website) bared that broccoli lost nearly 4 percent of its weight in 16 hours when not misted, while it added almost 5 percent in weight over that period of time when it was misted. Some vegetables are even more prone to weight loss, as carrots lost more than 7 percent of their weight in just 16 hours when not misted.

Even vegetables that are relatively immune to this problem, such as cauliflower and cabbage, lost more than 3 percent of their weight when not misted, but added 2 or 3 percent when properly misted.

Reliability of the employees responsible for keeping the misting system running well is paramount to avoiding a breakdown that could quickly become costly.

“It’s crucial to have a good service plan,” says Serhiy Hrytfay lead designer for Miatech. “You need good maintenance for any equipment that works with water. You need to replace the filters on time. You basically can’t ensure the system won’t break down, but we provide a warranty.”

Faced with the prospect of losing up to 5 percent of their produce weight literally overnight, produce retailers do well to think long and hard about which providers they trust to install and service a reliable misting system.

“An important point is the reliability of misting and the associated maintenance costs,” says Corrigan. “If retailers are throwing away more product, then their equipment is not doing its job. Misted produce is better quality produce that lasts longer. When a misting system is broken down, retailers’ investments are thrown away.

“A recent customer, that did not previously have a misting system, reported he weighed the product he was throwing out before and after installing the system. He determined that he saved more than 75 percent in lost product,” he says.

Suppliers of misting systems generally moved toward materials that resist corrosion and breakdown under the stress of constant moisture. “We use materials that are resistant to corrosion from the water,” says Corrigan. “We use a lot of plastic.”

The most likely place for the system to break down is clogging of the filters that ensure only the finest water is misted on the produce. “The trouble can come with reverse osmosis systems, because if you don’t change your filters on a regular schedule, it causes problems,” says Vered Kleinberger, marketing director at Prodew, Marietta, GA. “Our regular misting systems don’t go down. We have some out there that have been working for more than 10 years.”

Make It Finer

Corrigan has seen many advances in the technology since the days when his father invented the first misting system in the late 1970s. The latest improvement is in supplying a finer mist.

“If you go back to when most produce was wrapped in plastic, at night they would take burlap sacks and lay them across the produce,” says Corrigan. “My dad, who was an engineer, invented produce misting so you wouldn’t have to do that. There have been improvements in nozzle designs. There are low flow nozzles that give you a gentle mist. We’re just trying to protect the plants; refrigerating and misting protect the plants.”

The goal of the system is to produce a constant mist that is always around the produce, and never anywhere else. “A good humidity system will provide a fog that locally surrounds the product with a precise humidity level,” says Corrigan. “The system should not allow humidity to billow out into the store where it will wet floors and increase energy demand on the HVAC system. It is important to note humidity systems work best in an enclosed area as ever-changing temperatures, and air flow in the store have an adverse effect on the system’s output.”

One of the reasons finer mists are better are the smaller drops that are more easily absorbed. “When it comes to technology, the finer the mist the better,” says Hrytfay from Miatech. “The larger drops are not absorbed. as well by the produce.”

A crucial advantage of containing the moisture in or just above the produce is it avoids the nuisance of misting the customers, or even the potential liability of exposing them to wet floors.

“We have a low profile mist bar,” says Hrytfay. “It’s nozzle free and looks better. You also don’t wet the customer. Our mist is finer and friendlier. You don’t get wet, and you don’t get the floor wet.”

Wet floors are a good way to suffer lawsuits, and wet customers are a way to lose business. The simplest way to adjust the amount of water used to mist is to change the frequency of the pulse.

“If you are misting for 10 seconds and someone is standing there trying to buy something, that would be irritating,” says Corrigan. “If it goes on for two or three seconds, that’s not a problem. We do warning systems, or a sound system that goes with it.”

Suppliers are also offering choices in the angle and number of nozzles that allow retailers to use systems tailored to the designs of their produce displays.

“The goal for any misting technology should be to keep moisture in the product,” says Corrigan. “Eighty-degree round nozzles are typically installed in the canopy of the case and can be used in an alternating fashion with fan-style nozzles that prevent over spray and are best used with narrow product displays. The 80-degree nozzle also comes in a low-flow, gentle option that outputs half the flow of a standard nozzle for energy savings. There is also a 110-degree nozzle that is best for under-shelf installations or when the product is close to the mist bar.”

Misting is an evolving technology as producers are constantly working on systems that optimize the amount of fog that is available to the produce and nowhere else.

“The system you want depends on your case style and what you are misting,” says Prodew’s Kleinberger. “You can have variation in nozzle spacing at six, nine or twelve inches. You can also use single or double nozzle heads. We have six engineers who work in our office. As soon as we finish with the literature for a misting system, they are already making it better.”

The right system of gentle mist that keeps leafy greens and other produce items fresher longer pays for itself well before the end of the first year. The return on investment for misting technology is measured, not in years, but in months, as it reduces the amount of produce that must be thrown out while also guarding against weight loss from dehydration.

“On average it takes less than six months for a misting system to pay for itself; and it’s probably usually closer to three,” says Kleinberger. “The payoff comes from the lack of food waste and shrinkage. Refrigeration causes shrinkage, because it produces dehydration. Our fog mist keeps the humidity up, and stops the dehydration.”

Water Quality

A misting system can be no better than the quality of the water pumped through the nozzles to create the produce preserving fog. Although most municipal water is of good quality, there may still be chemical imbalances that must be remedied if the misting system is going to enjoy maximum longevity.

“The cleaner the water the better,” says Serhiy Hrytfay, lead designer for Miatech, Clackamas, OR. “The less minerals, the better. Usually we install our own systems with reverse osmosis.”

If you have hard water, and you don’t filter it through reverse osmosis, it scales up quickly, says Mike Corrigan, chief executive of Corrigan Mist, Gurnee, IL. “Poor water quality will clog nozzles and create scale buildup on mirrors, cases and water using equipment. A reliable reverse osmosis or water filtration system will prevent this from occurring. A good humidity system will not require filtration with most city water supplies.”

Even when the water is of the highest quality, it is common to install filters to prevent sediment from penetrating the system, according to Corrigan. Water contaminated by pathogens must be treated with ozone or UV light before it touches the produce.

“Bacteria is carried through the filter process,” says Jim Gross, president of Ozone Water Technologies, Greenville, SC. “If you use ozone, the bacteria, and possibly the odors that go with it, are eliminated. We’re putting ozone systems into laundries in hotels all over the world. It cleans up the water.”

He estimates a UV treatment system capable of handling the water in a large swimming pool, for example, would cost in the range of $8,000 to $12,000 to install. “We have a system that uses UV light to treat water,” says Gross. “It has to be done the proper way, but it works.”

These systems, when needed, worked without fail to prevent food safety problems that result from misting. “There have never been food safety issues or harm associated with misting equipment,” says Corrigan. “In the United States, produce misting systems are supplied water from municipal sources that are regulated by the EPA, local health departments and are tested for safety. Ozone is a terrific anti-microbial agent and can be added to any system where additional safety is desired.”

Once the water has been turned to mist, it generally does not have to be managed because it disappears into the produce or evaporates. “After it has already been used, the water for misting generally adheres to the produce; it is either absorbed or evaporated,” says Tom McKinney, sales manager at Ecologix Environmental Systems, Alpharetta, GA. “If retailers have runoff, they would need an oil/water separator, a sand filter — depending on what water treatment standards are in the area.”