Flowers harvested from the greenhouse should be pre-treated as soon as possible to preserve their quality and extend their shelf life. Proper post-harvest handling is essential to maintain freshness, color, and overall appearance. The following steps are commonly used in the pretreatment process.
1. **Post-Harvest Conditioning**
Once the flower stems are cut from the plant, they begin to lose moisture, which can lead to wilting and reduced visual appeal. To prevent this, it's crucial to place the flowers in water immediately after harvesting. This step helps rehydrate the stems and restore cell turgor pressure, ensuring the flowers remain firm and vibrant.
The conditioning process usually takes about an hour. It’s important to use clean water and, if available, a solution containing a fungicide to reduce the risk of bacterial or fungal growth. This not only improves the flowers' longevity but also enhances their overall quality.
2. **Pretreatment**
Before packaging, storage, or transportation, a short-term treatment of the flower stems with a sugar-based solution is often applied. This pretreatment is designed to improve the flowers’ performance during transit and storage.
The main objectives of pretreatment include:
- Enhancing bloom quality and extending the flowering period
- Allowing buds harvested at the early stage to open properly
- Ensuring that the flowers retain their quality after being transported or stored for a period of time
Common solutions used in pretreatment include sucrose and silver thiosulfate. For example, roses are often treated with a 10% sucrose solution at 20°C for approximately four hours to optimize their performance.
3. **Precooling**
Precooling is a critical step that involves rapidly removing field heat before the flowers are packaged, stored, or shipped. This is especially important for highly perishable products like cut flowers, as high temperatures accelerate decay and increase water loss.
By lowering the temperature quickly, precooling reduces respiration rates and slows down the aging process. The ideal precooling temperature is between 0°C and 1°C, with a relative humidity of 95% to 98%. The duration of precooling varies depending on the type of flower, the size of the container, and the cooling method used.
There are several methods for precooling:
- **Water Cooling**: This involves using ice water to cool the flowers directly. Adding a fungicide to the water can help prevent microbial contamination.
- **Air Cooling**: In this method, cold air is circulated through unsealed boxes to lower the temperature gradually before sealing. This technique is widely used in countries like Israel and is effective for maintaining flower quality.
After precooling, the flowers must be kept in a controlled environment to maintain their low temperature throughout the supply chain. Proper precooling not only improves the quality of the final product but also significantly extends its shelf life.
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