Cooling Of The Cut Flowers

Cooling of the cut flowers

Vacuum cooling

The empty cooling method is effective in products that have a high surface area ratio with respect to volume. The vacuum is based on evaporating the moisture present on the surface of the flowers quickly placed in a sealed container (vacuum chamber), since, by decreasing the pressure by a pump, it also decreases the boiling point of it, causing the materialdecrease your temperature. Good practice would also be to use vacuum pre-refraction which would not cause negative effects 

The main factors that influence the time and efficiency of the EV are: moisture, flower temperature, in this method, it should be considered that once the water is removed, the products should not have excessive damage in theirstructure, as it would cause the loss of quality of the same. Due to the above, the EV is more adequate and commercially used in flower cooling. 

This method considered one of the most effective in the field of flower cooling provides a 5-8 ° C temperature and managing to extend useful life of 12-13 days with a good physical appearance before senescence.

When we proceed to cool flowers by EV, they reduce the water losses of 2.5% for 1.5% and the cooling times of 65 for 45 s by sprinkling water prior to the cooled. 

However, when water is applied during the EV, it must be considered factors such as: the sanitization of water and the application equipment, due to the risk of an introduction of a pathogen in the products;In addition, water sprinkler should be performed evenly on the surface of the product, because excess moisture can overload the vacuum cooling system specifically.

(Sun and Brosnan, 2003)

Influence of the cold on the various physicochemical characteristics present in the cut flowers

The cooling is by far, the most important factor in the conservation of the quality of the cut flowers, ensure good cooling as soon as possible after the harvest, and that the optimal temperatures are maintained during the distribution process. 

According to what is studied, cold affects different ways in different types of flowers causing positive or negative effects on their physicochemical characteristics. Next, they detail how the cold affects the cut flowers.

He mentions that cold storage is an important process for cut flowers, this helps reduce breathing rate and reduce ethylene production by delaying senescence. Most flowers must be preserved at temperatures between 0 and 2 º C, however, this process in some cases damages the internal plant tissue producing chilling lesions, to solve this proposes to avoid mixed storage since there are sensitive cut flowers such as theOrchids dendrobium, anturies, birds of paradise, heliconias, etc. since, they cannot be stored at the same temperature as the rest of the species are commonly stored.

One of the most common conditions are chilling lesions, they are associated with lipid degradation in the membrane, this leads to a browning and an increase in electrolyte escape. In the investigation, it was determined that the spectrum of light is associated with the increase in electrolyte escape, and that for proper handling of cut flowers it must be carried out in a limited environment with light B spectrum in case the exposure to low temperatures areinevitable. Electrolytes or loss of water is linked to the speed of perspiration giving rise to the flower to wither, this phenomenon produces that enzymes such as peroxidase and catalase are activated by intervening as a defense mechanism to delay the senescence of flowers. These enzymes with adequate control work better in flowers stored in water showing better performance and avoiding the senescence of flowers.

As he mentions that there is a relationship between cold damage and oxidation photo caused by photo inhibition at low temperatures, this being the one that acts as a photo protection mechanism when excess energy is dissipated by the excitement absorbed as heat.

Another influence caused by cooling damage is the darkening of petals, water marks in them (which are transparent) and in severe cases collapse and death of leaves and petals. To avoid this, it recommends a rapid cooling accompanied by a stable cold chain, since this is essential to ensure the quality and life in a satisfactory vase from most cut flowers that are currently marketed.

The temperature is considered an important abiotic factor that can influence the respiratory rate, the response to ethylene, loss of humidity and physical damage in several flowers. The low temperatures being a main influence for stress in flowers with high sensitivity to ethylene, shortening its useful life. 

The low temperature accompanied by the packaging in modified atmosphere positively influences storage by reducing water loss, breathing rate and ethylene production, preventing darkening, some physiological deterioration and delaying microbes, development and decomposition such as the case ofThe Damascus rose, which its fermentation starts in flowers due to excessive temperature.

Another option for good storage is the low temperature accompanied by the packaging in modified atmosphere positively influencing storage, since it reduces water loss, breathing rate and ethylene production, preventing darkening, some physiological deterioration and delayingmicrobes, development and decomposition as is the case of the Damascus rose, which its fermentation begins in flowers due to excessive temperature.

Conclusions

• Corted flower cooling research methods such as cooling chamber, forced air and vacuum cooling were quite similar.useful in the same way.
• Although the methods are quite similar there are some minimum differences which we find that the best method to conserve cut flowers would be vacuum cooling giving a better aspect in their physical characteristics.
• The cold is a very complex parameter to take into account since it produces positive and negative effects in the cut flowers its adequate control helps to prolong its useful life.
• The influence of the cold in the flowers entails certain risks such as chilling lesions they produce a deterioration of flowers affecting their physicochemical characteristics to avoid it, it is recommended to respect the temperature resistance parameters of each species.
• Wittering or darkening flowers is caused by cold lesions, it is advisable to subdue flowers to the same treatment or rapid cooling.