Big Isle fruit growersBy Rod Thompson
looking into X-rays
HILO -- Big Island fruit growers have successfully tested X-ray treatment as a means of killing fruit flies in tropical fruit, supporters of the process have announced.
The tests at Iowa State University could provide an alternative to current plans to use radioactive materials to kill fruit flies.
Federal rules require killing of the flies before the fruit can be shipped to the mainland. A treatment facility would allow major expansion of the Big Island fruit industry.
The announcement of the successful test was made by restaurant owner John Clark, based on reports from Iowa by Big Island fruit grower Eric Weinert.
Clark, Weinert and others held a tasting of the treated fruit by invited guests last week at Clark's restaurant, Fiascos.
State agriculture official Lyle Wong said he arranged for the fruit, papayas and rambutan, to be flown to Minneapolis and then trucked to Iowa.
Federal rules already allow fruit treatment using "ionizing radiation," whether from radioactive material such as cobalt-60 or from X-rays, Wong said.
Clark's announcement said growers were testing whether the fruit would retain its color, texture and taste.
Despite the growers' optimism, experts remained cautious about the commercial viability of X-ray treatment.
Isomedix Services, now part of Steris Corp., has been negotiating a site for a cobalt irradiator on Bishop Estate land near Hilo airport. The cost of that facility is about $2 million.
Wong said the Titan Beta company of San Diego recently gave $10.5 million as the price for an X-ray facility, although more recently Wong heard $6 million.
Clark said the cost per pound of X-ray treated fruit would be more than for cobalt treatment but less than for existing, conventional treatments.
University of Hawaii food irradiation researcher James Moy said an X-ray system presents difficulties. The X-rays, far stronger than medical X-rays, start with an electron beam, a well-known technology but too weak to treat fruit.
In a relatively new technology, the electrons strike a metal plate to produce X-rays. But the process uses a lot of electricity, about 90 percent of which is wasted as heat.
"I know that it would be a big draw on electricity. The machine is also very complicated," Moy said.
An engineer with spare parts would be required on site at all times, he predicted. A cobalt irradiator is much simpler, essentially radioactive material stored in a tank of water, then raised to bombard fruit when needed.
The advantage of an X-ray machine is absence of radiation when it is turned off.