Cut Flowers

In the past thirty years, the market for cut flowers has become a global one; flowers and cut foliage sourced from throughout the world are sold as bunches or combined into arrangements and bouquets in the major target markets, such as North America, Japan, and the EU. The high export value of cut flowers has led to dramatic increases in production in many developing countries. Production of cut flowers and foliage can be highly profitable in countries with an ideal growing environment (particularly those close to the equator), and low labor costs. The costs of establishing production in the field or even in plastic houses are relatively modest, and harvest may start within a few months of planting.

Because of this global production system and marketplace, and the high perishability of cut flowers, air transport has been the transport system of choice. Although air transport is rapid compared to surface modes (truck, sea container, etc.), the nature of cut flowers and foliage leads to their rapid deterioration even during the relatively few hours that they are in transit when transported by air. It has frequently been demonstrated that transport of flowers in surface modes that permit maintenance of the cold chain results in better out-turns than air freight under uncontrolled temperatures.

Cooling

By far the most important part of maintaining the quality of harvested flowers is ensuring that they are cooled as soon as possible after harvest and that optimum temperatures are maintained during distribution. Most flowers should be held at 0 - 2°C. Chilling sensitive flowers (anthurium, bird of paradise, ginger, tropical orchids) should be held at temperatures above 10°C.

Individually, flowers cool (and warm) rather rapidly (half cooling times of a few minutes). Therefore, while individual flowers can be cooled quickly, it is also true that individual flowers brought out of cool storage into a warmer packing area will warm quickly and develop condensation prior to packing. The simplest method of ensuring that packed flowers are adequately cooled and dry is, therefore, to pack them in the cool room. Although this method is not always popular with packers, will probably increase labor cost and may slow down packing somewhat, it ensures a cooled, dry product.



Once packed, cut flowers are difficult to cool. Their high rate of respiration and the high temperatures of most greenhouses and packing areas result in heat build up in packed flower containers unless measures are taken to ensure temperature reduction. It is therefore necessary to cool the flowers as soon as possible after packing. Forced air cooling of boxes with end holes or closeable flaps is the most common and effective method for pre–cooling cut flowers. In forced–air cooling, refrigerated air is sucked or blown through a packed box of flowers to reduce their temperature quickly. Most flowers can be cooled to recommended temperatures in 45 min to an hour, and some cut flowers can be cooled in as few as 8 min. For small volumes of packed flowers, this is done by stacking boxes around a fan inside an existing cooler.

In larger systems, many fans are permanently mounted against a wall, and pallets or cartloads of flower boxes are positioned next to the fans. The refrigeration system needs to be carefully designed and sized for forced–air cooling.

Cooling time calculations

The time necessary to reach a desired temperature is expressed in terms of a typical cooling curve.


Source: IATA

Note: Cooling curve for cut flowers in a forced air cooler with supply air at 32 F / 0 ° C. The half-cooling time for these flowers is 10 minutes.

Categories

Fruit is defined as the edible product of a plant or tree, consisting of the seed and the envelope, especially the latter when juicy and pulpy. Fruits are usually soft, fleshy, edible plant products and, because of their high moisture content, are relatively perishable in the freshly harvested state.

The vegetables exhibit a wide variety of plant structures. They can be grouped into three main categories: seeds and pods; bulbs, roots and tubers; flowers, buds, stems and leaves.

Like human beings, fruit and vegetables are 'living' structures as they continue to respire even when detached from the plant. Respiration (consumption of oxygen with release of carbon dioxide plus water vapor) is the major metabolic process that takes place in harvested produce or in any living plant product. It can be described as the breakdown of complex material normally present in the produce such as starch, sugars, organic acids, into simpler compounds, such as carbon dioxide and water. This process is associated with the production of energy (heat). The respiration rate of a produce is an excellent indicator of the metabolic activity of the tissues and is therefore, a useful guide to the potential storage life of the produce. As the temperature of the surrounding environment increases the respiration rate of the product increases while shelf life decreases due to the loss of stored reserves. In general, the higher the respiration rate of a fruit or vegetable the more perishable the product is.

Based on their respiration and ethylene production patterns during maturation and ripening, fruits can be classified as climacteric or non-climacteric. Climacteric fruits show a large increase in carbon dioxide and ethylene production rates that are coincident with ripening, while non-climacteric fruits show no changes in their generally low carbon dioxide and ethylene production during ripening.

Classification of Some Fruits According to their Respiratory Behavior During Ripening