Postharvest handling of cut flowers through pre-cooling .
The market for cut flowers is a global one, with the high export value of cut flowers leading to a dramatic increase in production in many countries. However, across the globe, many flower supply chains are still underperforming. According to FlowerWatch, at least 20% of flower produce is unaccepted due to inadequacies of the cold chain, increased heat exposure and therefore fast flower decay. Yet, the most important aspect of flower quality is freshness and vase life, and both these aspects depend on optimum cooling.
Kenya is one of the biggest exporters of cut flowers, accounting for 38% of imports into the European Union. Most stems are traditionally transported around the world by air, using both cargo planes and passenger aircraft bellies. Considering air transport is rapid compared to surface modes (trucks, sea containers, etc.) many flower farmers overlook pre-cooling, despite how much it impacts quality and vase life. With the impact of COVID-19 on global logistics, the capacity to use airfreight has recently been cut by an estimated 25-30%, with a significant rise in freight charges, and the unavailability of reliable cargo planes. For this reason, the adoption of sea freight, accompanied by the longer transit periods has increased, calling for more efficient pre-cooling.
The cold chain, particularly for cut flowers must start on-farm, right after flowers are picked and cut. For most farms, flowers are shipped to the airport within 48 hours, after picking. During this time, the temperature and humidity conditions ought to be controlled, bringing down the temperature and keeping an ideal range of 1 to 3°C. A pre-cooling treatment before and after grading and after bundling packages for shipment in reefer trucks assures quality control, by slowing down decomposition, cutting down weight reduction and shrinkage.
FlowerWatch standards suggest following the 500-degree hour norm (1-degree hour = 1 hour x 1° C away from the flower’s target cold chain temperature). Each 500-degree hour reduces vase life by one whole day, so the key objective is to reduce the number of degree hours since the flower is cut and not to lose more than one day of vase life before the flowers are sold. If we imagine a batch of flowers taking 5 days (120 hours) from the harvest to the retailer and those flowers are kept at 7°C instead of 2°C due to an under-dimensioned or badly managed cold chain, we are already at 600-degree hours, drastically reducing the value of the flowers that will decay quickly after being sold.
The respiration of cut flowers generates heat as a by-product, and as the ambient temperature rises, the respiration rate increases. The rate of ageing can be reduced dramatically by cooling down the flowers at an optimal temperature as soon as possible. Pre-cooling can bring the flower to optimal temperature in 15 to 60 minutes, while standard cooling alone can take a day, which means more degree hours spent at the origin.
How is InspiraFarms supporting growers with precooling?
We take great pride in being precooling specialists with outstanding know-how on dimensioning the pressures, airflows and cooling capacity required by each flower stem. This allows the pressure and airflow to force cold air through the packaging, allowing the core of the product to cool down. In turn, this reduces floral activity, delaying senescence, and extending shelf-life.
To optimise this process further, we additionally provide remote monitoring systems, to utilise data and ensure the visibility of the process to off-takers. The use of humidifiers to keep high relative humidity can be added for certain flowers, and it can be also supplied by InspiraFarms. InspiraFarms offers blast chillers and forced air pre–coolers, providing control and flexibility over pre–cooling. The technology speeds up the cooling to equally and effectively reach every package on a pallet, crate, box or bin. A tarp included in the system is laid across the top and back of the stock, allowing it to seal and keep the flow of cold air through the flowers, rather than around it. When the fan is turned on, it pulls or forces the airflow through the boxes, removing the heat through convection. When done efficiently, the airflow is optimised and the period for the temperature drop of the produce is significantly shortened. With pressures of up to 300 Pa (Pascal), our pre-cooling systems and adjustable airflows allow it to match it with a range of cooling machines and your cooling processes and needs.
In conclusion, flower producers and exporters that want to optimise their flower quality, and reduce rejection and shrinkages, ought to optimise their cooling operations, lest they lose a good share of their potential margins to freight, rejections, shrinkage and fungi. With whatever freight mode is selected, pre-cooling at the farm must be a common practice.
