Beans

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Infobox on Beans
Example of Beans
Beans.jpg
Freshness facts
Optimum carrying temperature 5°C to 7,5°C (Snap and French beans)
O°C to 1°C (Broad beans)
Highest freezing point -0,7°C
Acceptable product temp. at loading into containers Max. 2°C above carrying temperature
Optimum humidity 95%
Ventilation setting for containers 25 m³/hr
Storage life 1-2 weeks (Snap and French beans)
2-3 weeks (Broad beans)
Climacteric / non-climacteric Non-climacteric
Ethylene production Low
Ethylene sensitivity Medium
Modified / controlled atmosphere 2%-5% O2; 4%-8% CO2
Potential benefits Moderate
Availability
Netherlands May - October

Harvesting and Handling

Of snap beans and long beans both the fleshy pod and seeds are consumed. They include fresh snap or common beans (string beans, yellow wax beans, green beans), runner or flat beans and long beans.

Beans should be well formed and straight, bright in colour with a fresh appearance free of defects, and tender (not tough or stringy) but firm. The diameter of the pod, rather than length, is a good indicator of quality. Buyers prefer pods with no or only slight bulges, indicating tender, young seeds. As the name implies, snap beans should break easily when the pod is bent, giving off a distinct audible snap. Poor quality is most often associated with over-maturity, broken beans, water loss, chilling damage and decay.

Snap beans (yellow, green and purple types) are harvested when they are rapidly growing; about 8 to 10 days after flowering for typical mature snap beans. All pod beans should be harvested when the pod is bright green and fleshy, and the seeds are small and green. After that period excessive seed development reduces quality and the pod becomes pithy and tough, and loses its bright colour.

Cooling and Storage

Snap beans can be hydro-cooled, and this is especially beneficial in dry climates where dehydration is a concern, and in situations where evaporation of surface moisture occurs rapidly after cooling, i.e. beans packed in wire-bound crates. Although hydro-cooling is very rapid, significant postharvest decay can occur if the product remains wet after cooling. Forced-air cooling is the method of choice if beans have been packed. Although efficient cooling is achieved without leaving free moisture on beans, water loss does occur.

At 5°C to 7,5°C a commercial storage life of 1-2 weeks is expected for snap and French beans.

Snap and pod beans are chilling sensitive, and visual symptoms will depend on the storage temperature. At temperatures below 5°C, the typical symptom of chilling injury is a general opaque discolouration of the entire bean. A less common symptom is pitting on the surface and increased water loss. At temperatures of 5°C to 7,5°C, the most common symptom of chilling injury is the appearance of discrete rusty brown spots. These lesions are very susceptible to attack by common fungal pathogens. Beans can be held about 2 days at 1°C, 4 days at 2,5°C, and 6 to 10 days at 5°C before chilling symptoms appear. No discolouration occurs on beans stored at 10°C, but undesirable seed development, water loss, and yellowing will occur at this storage temperature. Different varieties differ substantially in their susceptibility to chilling injury.

Freeze damage appears as water-soaked areas which subsequently deteriorate and decay. Freezing injury occurs at temperatures of -0,7°C or below.

Controlled atmosphere considerations

The main benefit is retention of colour and reduced discolouration and decay on physically damaged beans.

Storage disorders

Alternaria blight, Anthracnose, Ascochyta pod spot, Blight, Cottony leak, Fusarium, Grey mould rot, Mosaic virus, Rhizoctonia solani, Sclerotium rot.