Extending the shelf life of the new BimiReg. broccoli by controlled atmosphere storage.

摘要

The new BimiReg. broccoli is a natural hybrid between kailan (Brassica oleracea Alboglabra group) and conventional broccoli (B. oleracea Italica group). This new Brassica has a tender stem (similar to asparagus) and a small floret. Its mild flavour (compared to conventional cultivars) makes this vegetable ideal for fresh-cut purposes, besides their nutritional benefits. However, BimiReg. is very perishable, being yellowing, stem bent, off-odours and off-favours the main sensory quality parameters affecting its postharvest life. Controlled atmosphere storage (CA) has been described as a very effective technique to maintain broccoli quality. The aim of the present work was to study changes in the sensory quality, pH, titratable acidity (TA), soluble solids content (SSC), stem firmness and colour changes under 5 different CO₂ CA (5, 10, 15, 20 and 25 kPa CO₂ + with 2 kPa O₂ + balanced with N₂) throughout 27 days at 2, 5 and 8 degrees C. A control under air conditions was used. Better sensory scores were reached under 10 kPa CO₂. However CA of >=15 kPa CO₂ avoided stem bent during 27 days at 2 and 5 degrees C. Samples stored at 8 degrees C were excluded due to yellowing and the high stem bent observed. Low moisture loss (0.5-1%) was registered after 27 days for both storage temperatures. Stems showed a luminosity increase around 23% after 6 days, without differences at both temperatures. The initial pH (6.0) rose approximately 3.5% after 6 days at both temperatures, with no changes until the end of the storage. Initial TA values (0.18 g citric acid 100 ml-1) did not show changes during 19 days at both storage temperatures. However, after 27 days TA content increased between 14-40% for both storage temperatures, showing the higher the CO₂ concentrations the lower the TA increases. No stem firmness and SSC changes were found throughout storage at both temperatures. In conclusion, CA storage with 10-15 kPa CO₂ (+2 kPa O₂ balanced with N₂) provides great benefits for keeping the quality of BimiReg. broccoli during cold storage, reaching an acceptable sensory quality after 27 days of shelf life at 2 to 5 degrees C.