The development of off-flavor in frozen-thawed strawberries was attributed to the production of HzS. The identity of H2S was verified both chemically, through its reaction with lead acetate, and using gas chromatography-mass spectroscopy analyses. The duration of the production of HZ!3 was longer in berries stored at -40“C and -80°C than in those stored at -20°C. Because the amount of sulfide ion in frozen strawberries was lower than that in fresh berries, and because KzS addition resulted in further increases in the production of H2S, it is likely that H?S evolution is due to the decrease in pH of the cytosol caused by the disruption of cells by freezing, resulting in the release of sulfide ion as H2.S. Vigorous crushing of fresh berries also gave rise to the production of H2S.