High CO2 Reduces Spoilage Caused by Botrytis cinerea in Strawberry Without Impairing Fruit Quality

High CO 2 (> 20 kPa) conditions are beneficial for suppressing spoilage caused by Botrytis cinerea in strawberry fruit; however, these conditions are often accompanied by discoloration, off-flavors, and faster softening. Stepwise increments of CO 2 concentrations have been proposed to alleviate injuries in fruits caused by high CO 2 . In this study, we investigated whether stepwise increments of CO 2 , up to 30 kPa and under a reduced O 2 concentration, are beneficial for reducing fungal spoilage without inducing CO 2 injury symptoms in strawberry fruit. Based on recommended settings (5–10 kPa O 2 with 15–20 kPa CO 2 ), we first selected optimal O 2 and CO 2 concentrations that best-reduced spoilage caused by B. cinerea in red ripe “Sonsation” strawberry fruit. We found that higher O 2 (10 kPa) and CO 2 (20 kPa) concentrations were most beneficial for prolonging strawberry fruit shelf life. Subsequently, we studied the performance of red ripe “Arabella” strawberry fruit stored at 5°C under different controlled atmosphere (CA) conditions (10 kPa O 2 with either 0, 20, or 30 kPa CO 2 ). The CO 2 concentrations were achieved either within 8 h or in a stepwise manner within the first 4 days of storage. As a control, 21 kPa O 2 and 0 kPa CO 2 were used. Following storage for up to 11 days, the spoilage incidence was assessed at 12°C for 5 days. The application of high CO 2 (20 and 30 kPa) combined with 10 kPa O 2 greatly suppressed fruit spoilage during storage and subsequent shelf life. High CO 2 suppressed respiration as well as maintained a higher pH and firmness in treated fruit. The level of total sugars did not change, but during storage, a substantial part of sucrose was converted into glucose and fructose, especially under high CO 2 conditions. High CO 2 did not affect ascorbic acid and anthocyanin levels. The stepwise increments of CO 2 did not result in beneficial effects compared to the static application of high CO 2 . Our results show that “Arabella” strawberry fruit are highly tolerant to elevated CO 2 and can be stored under 30 kPa CO 2 to prolong the shelf life.