Feb. 24, 2002
When it comes to pizza ingredients, none is as simple to use as tomato sauce.
The process tomato industry that makes that sauce so simple, however, is anything but. The cycle of moving tomatoes from the field, to the factory and finally to the pizzeria's back door is one leaning on high technology every step of the way.
The harvest of process tomatoes is completely mechanized, requiring minimal human labor to operate the machinery. Even global positioning systems (GPS) are being used in by some growers to perfect field operations.
Just in California alone, an average 10.8 million tons of process tomatoes -- 95 percent of the country's supply -- are grown each year. Add in the rest of the process crop from about a half dozen Midwestern and Northeastern states, and you have a harvest with an average annual worth of $500 million.
Literally thousands of tomato varieties (called cultivars) exist today, but the processing industry uses almost exclusively those called square rounds.
According to Dr. Wilbur Gould, a retired professor at The Ohio State University's School of Food Processing & Technology, serious and systematic research into breeding better tomatoes for processing began in the 1940s. Gould, also the author of Tomato Production, Processing and Technology, said tomato processors charged breeders with developing genetic combinations that would produce tomatoes resistant to diseases and pests, have more consistent color and shape, and bear fruit that would ripen simultaneously.
Thousands of crossbreeds later, the industry not only has cultivars that do all the above, but ones bred specifically for use as paste, sauce or ketchup.
Dave Francis, an assistant professor in horticulture and crop science at OSU's Wooster campus, pointed to the turbulent '60s as a decade of profound change in the industry.
The mechanical harvester, a gurgling, 25-foot-long, diesel-powered machine was developed during the period. The machine's ability to minimize field labor was a boon for growers used to employing pickers by the hundreds.
But unlike humans, who picked tomatoes off the vine, mechanical harvesters gathered them by cutting the entire vine away from the ground and shaking the tomatoes free. If the vines held any unripe fruit, the "single-pass" harvester could reduce crop yield by denying growers a second chance to glean unripe fruit later.
The development of plants that bore concentrated sets -- meaning all the fruit ripened simultaneously -- was the answer.
"All the fruit on the same plant would turn red at the same time," said Francis. "(Breeders) also focused on how the fruit attached to the vine. They had to develop plants that tomatoes would fall off of without any stem on them."
The impact of those advances is clear and profound. According to the California Tomato Growers Association, California produced more than 3 million tons of process tomatoes in 1970, but by 1994, that number had skyrocketed to almost 11 million tons.
Gould, now 82, and living in Cape Coral, Fla., has seen the industry grow five fold since he began researching tomatoes in 1940.
"This business is not even the same," said Gould, who recalled the days when harvest waste was so high that tomato fields turned blood-red. "With all the automation and mechanization, it's gotten so much better, so much bigger. It's an amazing thing."
Tomatoes aren't the only thing mechanical harvesters pick up in the field; they gather data as well. Modern machines weigh the crop as it's picked, and some also can record the location in the field from which it came. Those numbers help growers examine which parts of the field yielded the most fruit.
Soil samples are then analyzed to understand why plants in some parts of the field perform better than others. And when growers prepare the soil for the next season, they're able to correct deficiencies with precisely targeted fertilization.
Help from Above
Ron Peters, founder and president of Louisville, Ky.-based Paradise Tomato Kitchens, travels to California regularly to watch the harvest of tomatoes used by his company.
"You really don't understand just how much technology is involved until you see it in operation," said Peters, whose company is a custom sauce manufacturer for pizza and restaurant chains. "When you're working with something pretty simple like tomato paste, which we do, it's easy to overlook how complex that part of the business really is."
Advances such as GPS, said Chris Rufer, founder of Morning Star Packing, headquartered in Los Banos, Calif., is just beginning to impact the tomato growing industry, though it's already used widely by grain producers.
"GPS can be used to structure your ground work, your fertilization program and your watering, all based on the characteristics of the field," said Rufer. "You can make very accurate accommodations for all of that."
Concentrated set: fruit on a tomato vine that ripens simultaneously and in uniform size.
GPS: global positioning systems. Satellites orbiting Earth communicate with ground receivers to enable users to pinpoint geographic locations. Tomato growers are using these increasingly to analyze field production rates and target watering and fertilization schedules.
Mechanical harvester: a machine that harvests tomatoes by cutting off the vines at ground level and shaking the fruit free from the vine. Developed in the 1960s, modern machines cost $300,000 and carry a crew of four to six.
Tomato cultivar: a specific variety of tomato, such as Roma. More than 2,000 tomato cultivars exist today.
Like Gould, Rufer stressed that technology has advanced the industry light years beyond where it was when he began as a tomato truck driver 30 years ago. But what he believes has made those advances most valuable is improved coordination between growers and processors.
"Coordination is happening at the processor level as opposed to the grower level, and that makes the flow between the field and the factory much better," said Rufer.
Tomato planting in California begins in February, is staggered through March and April, and finished in May. A 100-day harvest follows from July to September.
According to Rufer, tomatoes ripen at a rate of 2 to 3 percent a day, leaving growers a narrow window in which to accomplish the goal of harvesting all of them as close to peak as possible, without letting them over-ripen.
To accomplish this, processors and growers must know exactly when to dispatch the harvesters to the fields, and how quickly the crop can be brought to the cannery. The rate at which the factory can process is then synchronized to the rate of tomato delivery, and, ideally, the entire cycle recurs around the clock until the harvest ends.
In the past, Rufer said, when growers and processors weren't as well coordinated, the flow of fruit from the fields was less predictable, and back-ups resulted at canneries.
"Tomatoes begin to deteriorate and get softer as soon you pick them," said Rufer, whose company also has processing plants in Yuba City and Williams, Calif. "If you pick at the same rate you're processing, it doesn't wait at the cannery very long, an hour or two on average."
The science of tomato harvesting has indeed come a long way, resulting in higher yields, less waste and fresher-tasting products. Advances in this end of the industry also have helped pizza companies prosper by controlling costs and guaranteeing consistency.
In our next installment, we'll go inside a cannery and learn how raw tomatoes are transformed into the products used on pizzas.