Sweet Idea for Citrus : Scientist Tests Way to Avoid Bitter Juice

A biochemist at the U.S. Department of Agriculture’s research center in Pasadena may have solved a multimillion-dollar problem that has plagued the world’s citrus industry for years.

After 2 1/2 years of study, Shin Hasegawa thinks he has found a chemical that prevents newly squeezed fruit juice from becoming bitter.

Some juice, especially that from California navel oranges, develops a bitter taste within hours after being squeezed from the fruit, Hasegawa and industry officials said.

If successful, Hasegawa’s process could save the California orange industry from $3 million to $8 million a year, officials said. California accounted for 32.8% of U.S. orange production in 1985, according to the most recent state agriculture department figures available. The state’s orange crop was valued at $524 million.

Hasegawa and his team of researchers are about to take their discovery out of the laboratory and test it on trees in an orange grove in the San Joaquin Valley community of Lindsay. But it has already won praise from growers and fruit processors.

Dan Kimball, director of research and development for California Citrus Producers in Lindsay, said that Hasegawa’s experiments are moving the industry “closer than we’ve ever been” to finding a way to prevent the bitterness.

“We are very much excited about this, because it’s a very big problem in California,” he said. “We’re excited enough to bring him up here and see if it works.”

The bitterness, because of the chemical limonin, exists in the seeds and peels of all citrus fruits, including Valencia oranges, lemons and grapefruit. But it is most pronounced in seedless navels, which account for about half the orange production in California. After the fruit is squeezed, the taste of limonin grows stronger.

To counteract it, Hasegawa and his researchers have been concentrating on preventing the bitterness from occurring.

Hasegawa said that he and Edward D. Orme, Peter Ou, Zareb Herman and Chi H. Fong began experimenting two years ago with plant hormones that had been used on grapes and on apple and pear trees to prevent premature ripening. They hoped that the hormones, called auxins, would retard the development of limonin.

After injecting about 2,000 different auxins into citrus trees at their Pasadena laboratory, the scientists found one that worked, Hasegawa said. One California orange grower, Fred LoBue of LoBue Brothers Inc. in Lindsay, said that if bitterness can be prevented, it could make the difference between “surviving or not surviving” for some farmers during lean years.

Hasegawa said an experiment is scheduled to begin in May on about 10 to 15 navel orange trees in a California Citrus Producers grove in Lindsay.

Unlike the laboratory experiments, in which the trees were injected, the trees in the grove will be sprayed to absorb the naphthaleneacetic acid through their leaves. Injecting each tree would be impractical, Hasegawa said.