Vegetables Produce Facts English

General Information

Round hard cabbages and Chinese (also called Napa) cabbages are from the same genus (Brassica) but different species (B. oleracea var capitata = cabbage, B. campestris var. pekinensis = Chinese cabbage). 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 Indices

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.

Quality Indices

After trimming outer wrapper leaves, cabbage heads should be a color 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. For round cabbages, grades are U.S. No. 1 and U.S. commercial.

Optimum Temperature

Most cabbage is room cooled. Storage at 0°C (32°F) 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 (31°F) is sometimes recommended. Chinese cabbage can be stored from 2 to 6 months, depending on cultivar, at 0°C to 2.5°C (32°F to 36°F). 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.

Freezing Injury. 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 (30.4°F) and if Chinese cabbage is stored below -0.6°C (31°F).

Optimum Relative Humidity

>95%

Rates of Respiration

Round and Chinese cabbages have similar moderately low respiration rates:

Physiological and Physical Disorders

Black speck. Black leaf speck (also called pepper spot, petiole spot, gomasho) is a disorder that consists of very small to moderate size discolored lesions on the midrib and veins of the leaves. The symptoms can occur after low temperatures in the field and by harvesting overmature heads, but are usually associated with transit and storage conditions. Low storage temperatures followed by warmer temperatures enhance development. Ethylene does not promote development of black speck in Chinese cabbage. Both round and Chinese cabbage cultivars vary widely in their susceptibility to this disorder. Storage with high CO₂ atmospheres (10%) can reduce pepper spot development on round cabbage.

Chilling injury. In Chinese cabbage is purported to occur during storage at 0°C (32°F) 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.

Physical Injury. Breakage of the midribs often occurs during field packing and causes increased browning and increased susceptibility to decay. Outer midribs of overmature heads will crack easily.

Pathological Disorders

The most common decays found in stored cabbage are watery soft rot (Sclerotinia), gray mold rot (Botrytis cinerea), alternaria leaf spot (Alternaria spp.), and bacterial soft rot (caused by various bacterial species including Erwinia, Pseudomonas, Xanthomonas). Bacterial soft-rots result in a slimy breakdown of the infected tissue, and may follow fungal infections. Trimming outer leaves, rapid cooling and low temperature storage reduce development of these rots, although Botrytis and Alternaria will grow at low storage temperatures.

Special Considerations

Fresh-cut or shredded cabbage pieces brown during storage and atmospheres of 3-5% O₂ and 5-15% CO₂ retard discoloration. Too low oxygen levels lead to fermentation and package blow-up, especially if product is not held below 5°C (41°F).

August 2001