Chard, Beta vulgaris var. cycla / Chenopodiaceae
Postharvest Atmosphere Management
Chards are sold fresh or frozen. In we buy them fresh we must consume them as soon as possible so as to prevent them from loosing their nutritious properties. They are kept in the fridge for 4 days, improving their conditions if we put them without washing in a perforated bag.
The handling of chards for the domestic market is generally limited to dampen them with water in order to avoid blight. The rate of transport to the warehouse represents a problem when the boxes must be kept under the sun in hot hours waiting for the transport vehicle, causing fast blight.
Vacuum pre-cooling is a very suitable method. It is not a common practice, since this product is mainly destined to the domestic market, although it would enable the obtention of greater quality produce, reducing blight and preventing the development of fungi and bacteria. The end-temperature must be between 0 and 4ºC.
At temperatures between -0,5 and 0ºC and 95% of relative moisture, chards are kept for one or two weeks. The freezing temperature of this species is -1ºC; therefore, these temperatures must be avoided.
The use of modified atmosphere enables us to extend conservation up to one or two months. The concentration of oxygen must be around 10% and the levels of carbon dioxide around 2-3%. This method is not used in chards.
Distribution
In order to maintain an optimal quality in transport, the vehicles must be cooled at a temperature between 0 and 4ºC and relative moisture over 95%.
During the distribution, relative moisture must be high and temperatures must be between 5 and 10ºC. These conditions favour the fresh appearance of the vegetable. The accumulation of bunches must be avoided in order to diminish damages by crushing and to prevent the respiratory heat of the produce.
Postharvest Problems
Chards have a high respiratory and transpiratory activity, limiting their post-harvest life.
The main causes of losses in this species are blight, decoloration, mechanical damages and parasitic diseases.
Among the chief organisms that cause rottings we find the bacteria and the fungi Botrytis and Sclerotinia. The attack of the former is characterized by areas of pale brown colour on which the grey mycellium grows.
The most frequent mechanical damages are broken limbs and the petiole’s (stalk) craking.