2019 Volume 57 Issue 3 Pages 45-51
Concentration of sulforaphane in broccoli is known to be enhanced during storage under an atmosphere of low O2 (0.002–1.3％) and high CO2 (20.6–25.4％). However, maintaining this concentration at a maximum is problematic. Therefore, storage of broccoli florets at low temperatures was investigated. Results showed that storage for 2 days under hypoxia significantly increased (3.3-fold against initial value) sulforaphane concentration. Subsequently, 4 days storage at three temperature levels was conducted. Sulforaphane levels were not maintained at 20℃ (normal temperature) or 1℃ (cold temperature). However, after storage at -20℃ (frozen) for 4 days, the sulforaphane concentration was not significantly reduced compared with the maximum level on day 2. Meanwhile, this concentration was not significantly higher than those at 20℃ or 1℃ on the same day. Storage under hypoxic conditions is known to affect the flavor and taste of vegetables. Therefore, eight taste factors were objectively measured using an electronic tongue. Astringency and bitterness were stable and independent of storage period and temperature, while other tastes were significantly affected by storage period. The rich umami value at -20℃ was significantly higher than that at 20℃, and in general it was challenging to maintain taste values even for cold or frozen storage.