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From: Food Quality & Safety magazine, April/May 2006

It's a Green Light

Dorner’s 7400 Series Sanitary Conveyor and California Lettuce Grower Keep Things Clean and Green

by Joanne C. Twaddell

When it comes to growing lettuce, Hollandia Produce has a unique and efficient way of accomplishing the task.

The California-based nursery uses an above-ground process called hydroponic growing for lettuce and other produce. Instead of relying on nutrients in the soil, plants grown hydroponically thrive on a nutrient water solution that contains all of the minerals that the plants need.

The entire process, from a single seed to the packaging line, takes Hollandia less than three months to grow a head of lettuce. At the time of harvest, employees remove lettuce from the growing troughs and pick away any discolored leaves from the head. Their butter lettuce and watercress are harvested with their roots intact. They are then packaged in a see-through clamshell that functions as a mini-greenhouse and continues to supply nutrients, thereby extending the shelf-life.

While the amount of debris collected from one discarded leaf is minimal, Hollandia produces several hundred thousand pounds of lettuce each year. That resulted in a “growing” problem.

“We used to remove the debris by hand and had an area in front of us where we would just shovel it out,” explains Ton DeBruyn, purchasing manager for Hollandia Produce. A few years ago, he began looking for a conveyor system that would help with the tremendous amount of debris collected from the discarded leaves being carried away for disposal, and finding a way to quickly and efficiently move the lettuce along the packaging line.

DeBruyn needed to find a reliable conveyor system, one that was durable enough for continuous use, yet designed for daily wash downs. He chose two Dorner AquaPruf 7400 Series Sanitary Conveyors.

“It’s very good, very strong and very sturdy,” DeBruyn says. “I looked at a lot of different brands and this 7400 Series more than meets our expectations.” Hollandia Produce, he adds, was the first company to get the 7400 Series when it was released.

The 7400 Series offers a sanitary design and is built with a durable, stainless steel frame and no flat surfaces eliminating collection points for loose food scraps. The continuous TIG welding of the 304 stainless steel frame provides strength and eliminates fasteners in the food zone, which means a more sanitary environment. Bearings are 400 series stainless steel and filled with H1 FDA lubricant, making them a high quality bearing for stainless steel sanitary conveyors.

“A simpler and more open design is better for sanitation because there are no hidden pockets or harbor points for bacteria,” says Gary Wemmert, director of new product development and marketing at Dorner Manufacturing Corp. “The trade-off of having an open design is safety. We work hard to design a safe product that also offers fast and effective sanitation.”

Dorner recognized the need for stainless steel conveyors about four years ago. Until then, the company used steel and aluminum frames. “We decided to target the sanitary market as a strategic initiative,” Wemmert adds. This includes the food, pharmaceutical and medical arenas.

When equipment must be washed and wiped down in such sanitary environments, more severe and harsher chemicals are used, he explains. “Chlorinated bleach and aluminum are a bad combination. The bleach eats up the aluminum.” So the minimum requirement for these environments had to be using stainless steel.

At Hollandia, employees drop discarded leaves onto a 10-inch wide, 24-foot long conveyor at knee height. The conveyor carries the leaves to an 18-inch wide, 15-foot long, cleated 7400 Series conveyor, positioned at a 45-degree angle. Lettuce is then transported up an incline where it is dumped into a trash bin.

“The conveyer takes the debris right to the waste bin,” Debruyn says. “That is a major improvement. And the conveyor never quits. We run it non-stop, every day for eight to nine hours. It has worked out very well for us.”

An operator can completely disassemble the 7400 Series without tools in less than three minutes. “In less than 30 seconds, you can open the conveyor for washing down and cleaning without removing the belt,” Wemmert says. “Each section is identical so it is easy to put back together and you don’t have to be mechanically inclined.” Dorner has engineered the 7400 Series for multiple daily cleanings, offering a variety of options to speed up the cleaning process.

“It’s quick to take apart and easy to clean,” DeBruyn says. “We hose it down everyday. In the food industry, you have to be clean. It takes about 10 minutes and we’re done.”

The less time employees need to spend cleaning the conveyor is more time they can give to other projects. “It’s been a really great conveyor for us,” DeBruyn adds. “If our applications call for additional conveyors, we’ll definitely consider going with another Dorner.”

Proper Food Safety - Adjusted Accordingly

When it comes to sanitation, there are a few different levels of need depending on the actual product.

“If you put baked goods, fruit and vegetables, chicken and dairy out on a counter and leave them there for a week, some of those products may or may not be edible when you get back,” says Wemmert. “But for the chicken and the dairy, there is no way you’re going to eat it.”

It’s the same way with sanitation.

The lowest level of sanitation needed is for baked and confection goods, mid-level is fruits and vegetables followed by meat, chicken and seafood, and the highest level is dairy, Wemmert says. “Baked goods don’t need heavy sanitation because the product itself does not require it. But the sanitation design has to be able to accommodate all levels.” The sanitation process is increasing and that includes conveyors, he points out. Most meat companies run production for two shifts and then shut down for an entire shift to clean, sanitize and then do a swab test. If a company is not diligent, its reputation can be jeopardized. “So, if it takes them so many hours to clean, and they are able to cut that time in half, their production time will increase,” Wemmert adds. “Our effective sanitation conveyor can help them clean faster.”

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