TOLERANCE OF STRAWBERRIES TO LOW O2 AND/OR HIGH CO2 ATMOSPHERES

Controlled atmospheres (CA) with low O 2 and/or high CO 2 concentrations are effective in maintaining quality and extending the postharvest life of strawberries. The efficacy of CA in controlling decay and insects (to meet quarantine requirements) requires O 2 levels below 1% and/or CO 2 levels above 15%. The tolerance of strawberries to such fungicidal and/or insecticidal CA depends upon the cultivar, temperature, and duration of exposure. Development of alcoholic off-flavor is the main detrimental effect of low O 2 and/or high CO 2 stresses and is associated with accumulation of ethanol and ethyl acetate due to increased activities of alcohol dehydrogenase and acetyl CoA alcohol transferase. Strawberries tolerate exposure at 0 or 5°C to 0.5 or 0.25% O 2 (balance N 2 ) for 10 days, air + 20% CO 2 for 10 days, or air + 50% or 80% CO 2 for 6 days before alcoholic fermentation and other injury symptoms become objectionable. Keeping strawberries in non-injurious CA has positive residual effects on their flesh firmness, color, and composition after transfer to air.