Market Quality and Rate of Respiration of Head Lettuce Held in Low-Oxygen Atmospheres

Excerpts from the report Summary: The market quality of head lettuce was evaluated after 7 days at 36°, 41°, or 50° F. in atmospheres containing 0, 1/4, 1/2, 1, 2, 5 or 8 percent O2 or in air and after an additional 3 or 4 days in air at 50° F. Concentrations of and 0 and 1/4 percent O2 injured the lettuce. Gray dead patches on the wrapper and cap leaves and dead young heart leaves were the principal symptoms of injury. The injuries became more severe as the temperature was increased. Russet spotting was reduced substantially in all low-oxygen (02) atmospheres tested, regardless of temperature. The incidence of pink rib was not affected by low-02 atmospheres. The severity, however, was reduced in 1/2 percent O2 when all test temperatures are considered, but increased in 2 percent O2 at 50° F. Decay was reduced, but not significantly, in 1 percent O2. Low temperature was more effective in reducing decay than low O2