Harvesting and Handling
Cabbage is grown in most major temperate vegetable growing areas and is available year-round in most markets. Round hard cabbages and Chinese cabbages are from the same genus. Chinese cabbages may be cylindrical or rounded and may be less compact than round cabbages. Information mentioned here applies to both types unless stated otherwise.
Maturity is based on head compactness. A compact head can be only slightly compressed with moderate hand pressure. A very loose head is immature, and a very firm or hard head is mature. Over-mature heads are more susceptible to splitting; pathogens, physiological disorders and seed stalk formation. The presence of seedstalk is undesirable.
After trimming outer wrapper leaves, cabbage heads should be a colour typical of the cultivar (green, red, or pale yellow-green), firm, heavy for the size and free of insect, decay, seed stalk development and other defects. Leaves should be crisp and turgid.
Cooling and Storage
Most cabbage is room cooled. Storage at 0°C with >95% RH is required to optimize cabbage storage life. Early crop round cabbage can be stored 3-6 weeks, while late crop cultivars can be stored for up to 6 months. For the latter, storage at -0.5°C is sometimes recommended. Chinese cabbage can be stored from 2 to 6 months, depending on cultivar, at 0° to 2.5°C. Deterioration of cabbage during storage is associated with stem or seed stalk growth (bolting), root growth, internal breakdown, leaf abscission, discoloration, decay and black speck. Long-term storage usually results in extensive trimming of heads to remove deteriorated leaves.
Only three to six wrapper leaves should be left on the head. All loose leaves should be trimmed away before storage because they will interfere with air circulation between heads. Air circulation in the storage should be sufficient to maintain constant and uniform temperature and RH around all cabbage heads. At higher than recommended temperatures, storage life is shorter. The end of storage life is signaled by increased respiration rate, core elongation and sometimes rootlet development on the core butt.
Cabbages are sensitive to ethylene, which causes leaf abscission and leaf yellowing. Adequate ventilation during storage is important to maintain very low ethylene levels. Chilling injury in Chinese cabbage is purported to occur during storage at 0°C after 3 months or longer. The main symptom is midrib discoloration, especially on outer leaves. Cultivars differ greatly in their susceptibility to develop midrib discoloration. Freeze damage appears as darkened translucent or water-soaked areas that will deteriorate rapidly after thawing. Freeze damage can occur if round cabbages are stored below -0.9°C and if Chinese cabbage is stored below -0.6°C.
Controlled atmosphere considerations
Some benefit to shelf-life can be obtained with low O2 (2%-3%) and high CO2 (3%-6%) atmospheres at temperatures of 0-5°C. CA storage will maintain colour and flavour of cabbage, retard root and stem growth, and reduce leaf abscission. O2 atmospheres below 2% for round cabbage and 1% for Chinese cabbage will cause fermentation, and CO2atmospheres >10% will cause internal discoloration.
Alternaria rot, Bacterial rots, Black rot, Cercosporella spot, Downy mildew, Grey mould rot, Leaf spot, Mosaic virus, Powdery mildew, Rhizoctonia rot.