Microbiological and Quality Responses of Strawberry Fruit to High CO2 Controlled Atmosphere and Modified Atmosphere Storage

Abstract

‘Minomusume’ strawberries were stored in high CO2 atmospheres (20%, 30%, and 40%) by means of a controlled atmosphere (CA) and active modified atmosphere packaging (MAP) for 10 days at 5 °C. The CA of 20% to 40% CO2 was effective in delaying an increase in fungal count and preventing the external formation of mold mycelia, but a CA of >30% CO2 induced black discoloration on the surface of strawberry due to CO2 injury. When strawberry fruit were stored in a MAP flushed with either air or high CO2, all packages approached an equilibrium of ≈20% CO2 and 2% O2 by the end of storage. Fungal counts of strawberry fruit stored in a MAP remained constant throughout the storage period and the diversity of fungal flora was partially similar regardless of the difference in the MAP method. Visual quality (mold incidence and severity of black discoloration) and physicochemical quality (weight loss, firmness, pH, and total ascorbic acid content) were unaffected by CO2 atmospheres as the flushing gas during active MAP storage, except that the fruit in a MAP flushed with 20% and 30% CO2 were firmer than those with air and 40% CO2. After transfer to ambient conditions for 6 days at 10 °C, however, external formation of mold mycelia identified as Botrytis cinerea and surface black discoloration were induced in strawberry fruit in MAP flushed with 30% and 40% CO2.