Among the Government witnesses at the trial was a Beech-Nut chemist who called the bogus product, which had been labeled as pure fruit juice, ''a chemical cocktail.'' Last Fall's Court Proceeding

During the trial Mr. Roche, an Assistant United States Attorney, said, ''This case is a story of corporate greed and irresponsibility.'' He said the defendants' ''main concern was making money for Beech-Nut, even if it meant selling a phony product.''

Last November Beech-Nut pleaded guilty to 215 counts charging that it shipped mislabeled products purporting to be apple juice with intent to defraud and mislead the public.

As part of the plea agreement, 145 other counts, including conspiracy and mail fraud, were dismissed, and the company agreed to pay a $2 million fine. Government officials said they believed the fine was at least six times as great as any paid under the Food, Drug and Cosmetic Act, which became law in 1938.

Beech-Nut's current president, Dr. Richard Theuer, said last November that the misrepresented juice, although not what it was supposed to be, presented no danger to health. He said the company had taken measures to prevent any similar incident.

Beech-Nut also agreed to pay $140,000 in investigative costs to the Food and Drug Administration. Beech-Nut, a subsidiary of Nestle S.A. of Switzerland, is based in Fort Washington, Pa.

At the same time, two other defendants, both suppliers of the bogus apple juice concentrate used by Beech-Nut, pleaded guilty. They were Zeev Kaplansky, president of the defunct Universal Juice Inc., and Raymond H. Wells, owner of the defunct Food Complex Company.