Degreening

Summary

The video script discusses 'The Greening' process in agricultural commodities, specifically for citrus fruits like oranges. It involves removing the green pigmentation or chlorophyll from the fruit peel to make it visually appealing to consumers. Ethylene gas or temperature treatments are used to expedite this process, which is suitable only for mature fruits that won't continue to ripen post-harvest due to their non-climatic nature. The script outlines the steps for an effective degreening process, including ensuring fruit maturity, applying fungicides, maintaining ethylene levels, monitoring carbon dioxide, and maintaining high humidity. It clarifies that degreening does not improve fruit quality and distinguishes between ethylene gas and calcium carbide, the latter being an artificial ripening agent.

Takeaways

• 🟢 The 'Greening' process refers to the removal of green pigmentation or chlorophyll from certain fruits, especially citrus fruits like oranges, to improve their visual appeal to consumers.
• 🍊 Ethylene gas or temperature treatments are commonly used to accelerate the 'Greening' process, which is applicable to mature fruits only.
• 🚫 Immature fruits are not suitable for 'Greening' due to their high acid and low sugar levels, which do not meet quality standards.
• 🌡 Citrus fruits are non-climatic, meaning they do not continue to ripen after harvest, unlike tomatoes, peaches, or pineapples.
• 🌳 Chlorophyll, the green pigment in plants, is responsible for the green color in citrus fruits, and its degradation by ethylene is a natural process.
• 🍂 The natural 'Greening' of citrus peel occurs when night temperatures are cooler in late autumn, but may not happen if the weather is too warm.
• 🍋 Mature Valencia oranges can 'regreen' in summer heat after a natural color has begun, highlighting the influence of temperature on the 'Greening' process.
• 📏 To ensure the best outcome during 'Greening', it's important to check that the fruit is mature with more than 50% color development.
• 💧 Fruit with dark green blood shells may not color well after harvest, indicating the importance of selecting appropriate fruits for the process.
• 🍇 After applying an initial fungicide to prevent post-harvest treatments, it's crucial to let the fruit dry before loading it into the 'Greening' room.
• 🌡️ The 'Greening' room should maintain a controlled temperature of 20 to 25°C up to 29°C, which is suitable for fruit from humid subtropical regions.
• 💨 High humidity levels (around 95% relative humidity) are necessary during 'Greening' to prevent excessive fruit weight loss.

Q & A

What does 'The Greening' refer to in the context of AB materials and agricultural commodities?

The Greening refers to the process applied to certain fruits, particularly citrus fruits like oranges, where green pigmentation or chlorophyll is removed from the fruit peel to make it more visually appealing to consumers.

What methods are typically used to accelerate the de-greening process of citrus fruits?

The de-greening process typically uses ethylene gas or temperature treatments to speed up the removal of green pigmentation from the fruit peel.

Why is only mature fruit suitable for de-greening?

Only mature fruit is suitable for de-greening because immature fruit has very high acid levels and low sugar levels, which do not meet the standard. Additionally, citrus fruit is non-climatic, meaning it will not continue to ripen after harvest.

What is the role of chlorophyll in citrus fruits and how does it relate to the de-greening process?

Chlorophyll is the green pigment in plants and is responsible for the green color in citrus fruits. The de-greening of the skin is a natural process of chlorophyll degradation by ethylene on the tree.

How does the natural de-greening process occur in citrus fruits on the tree?

The natural de-greening of the peel happens when night temperatures are cooler in late autumn. Even though the fruit may be mature inside and ready to eat, the weather may be too warm for natural color development.

Can mature Valencia oranges regreen during summer due to heat?

Yes, a similar process in reverse can happen with mature Valencia oranges in summer where the fruit can regreen due to heat after a natural color has begun.

What are the criteria for fruit to be de-greened in the packing shell according to Australian Citrus standards?

Only fruit that meets Australian Citrus standards (ACS) should be de-greened in the packing shell.

What are some considerations to ensure the best outcome during the de-greening process?

To ensure the best outcome, it's important to ensure the fruit is mature with more than 50% color development, branch the fruit with an initial fungicide to prevent post-harvest rot, let the fruit dry before loading it into the de-greening room, and maintain controlled doses of ethylene and suitable temperature and humidity levels.

Why is it important to monitor carbon dioxide levels in the de-greening room?

It is important to monitor carbon dioxide levels because harvested fruit is still respiring and releasing carbon dioxide into the room. High levels of carbon dioxide can inhibit the de-greening process and also reach unsafe levels for people entering the room.

What is the recommended humidity level in the de-greening room and why is it important?

The recommended humidity level in the de-greening room should be around 95% relative humidity. Maintaining high humidity levels is important to prevent excessive fruit weight loss during the de-greening process.

Does the de-greening process improve the eating quality of the fruit?

No, the de-greening process does not improve the eating quality of the fruit. It is a visual enhancement and does not affect the taste or nutritional value.

How does the use of ethylene gas in de-greening differ from calcium carbide or curu?

Calcium carbide or curu reacts with moisture to produce acetylene gas, which mimics the action of ethylene and is used as an artificial ripening agent. However, acetylene is not as effective as ethylene, and a much larger quantity must be used for the same effectiveness.