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Switching to sprout inhibitor ethylene: safe and cost efficient

The corona crisis is causing a decrease in the demand for potatoes for the processing industry. As a result, sprout inhibitors for good safe storage are in the spotlight again. One of the most used sprout inhibitors at the moment is ethylene. What explains its popularity? And what do you need to take into account if you are considering a switch? Fernando Rubio L├▓pez, ethylene expert and technical manager at Restrain, explains.

Natural sprouting inhibition based on ethylene is rapidly gaining ground in the potato chain. Many growers and large processors like McCain Foods UK already switched over. Last year, more than 1,000 potato growers and processors switched to Restrain’s ethylene sprout inhibition. The method is currently applied in 40 countries on a total of more than two million tonnes of potatoes worldwide.

Besides the consequences of the corona crisis, the recent ban on the sprout inhibitor CIPC also boosted the popularity of alternatives. Now that CIPC sprout inhibitor is no longer permitted, many countries and parties in the potato chain have already stopped using CIPC for the 2020 harvest. We notice that users who turned to alternatives such as mint oil, orange oil and DMN are now also exploring the possibilities of sprout inhibition with ethylene. This is because ethylene is a lot cheaper than the alternatives. In addition, the method is odourless. Despite these advantages, making the switch can feel like a big step. But it is actually very simple.

How it works

Restrain works with a generator that converts liquid ethanol into ethylene gas. The software-controlled generator continuously distributes a low concentration of ethylene evenly throughout the potato storage. After three days of exposure to ethylene, the sprouting process of the potatoes in the storage is blocked. A supplied sensor measures the ethylene concentration in the storage. The smart generator automatically adjusts the gas production to the measured values. The concentration of ethylene used is low. This makes the method cost-effective and safe. Moreover, the gas is natural and leaves no residue.

No storage adjustments

Sprout suppression with ethylene is suitable for all types of storage, regardless of the storage size and the (un)used storage capacity. It is also effective in non-airtight storages, storages with cooling and storages with longitudinal aeration. When switching to Restrain, users do not need to change their storage method. It works in virtually all forms of storage – bulk, boxes and on a grid floor. The Restrain generators have a large capacity. A single generator can handle an area with 5,000 tonnes of potatoes. This contributes to the cost-efficiency and popularity of the method.

Daily ventilation

When using ethylene, it is important to ventilate your storage area daily. At Restrain we advise you to circulate the air inside the storage for one hour every 24 hours to ensure the ethylene mixes optimally. For the best results it is advisable to ventilate the storage externally for one hour immediately afterwards to remove CO2.

Application to potatoes with small sprouts

Ethylene sprout inhibition is also suitable for potatoes on which sprouts are already visible. After a few days of treatment, the application blocks the emerging sprouts. During the storage period the sprouts remain on the potatoes, but they become brittle and break off when they are moved out of storage. At the time of delivery there are no more sprouts visible. Moreover, sprouts do not need to be burnt off. As a result, there are no burn marks on the peels and the quality of the peel is better.

Fry colour results

Restrain is suitable for use on the Agria, Fontane and Markies potato varieties, the main varieties used by the processing industry. The method achieves good results in fry colour tests by independent researchers and customers are pleased with the effectiveness of ethylene. Jeff Beever, Agronomist at McCain Foods (GB), says: “At McCain, we’ve been closely following the development of Restrain and using it on commercial scale for a number of years. We have carried out multiple, comparative trials on the effectiveness of this sprout suppressant and tested how it affects the fry colour of our potato varieties. Our trials have been successful so, in storage season 2019/20, all our medium to long term storage has been kept with ethylene and we are now encouraging our growers to use Restrain as a sprout suppressant”.


Ethylene is a colourless, volatile gas that you cannot smell at low concentrations. In theory, the gas is dangerous at high concentrations, but Restrain’s generators are not technically capable of reaching those values. The ethanol concentrations Restrain works with are extremely low and therefore safe. The ethanol that serves as input for the generator, however, is flammable. Therefore, please take into account that you must not use fire or smoke near the generator and in the storage room.

Low costs

An important difference with alternative sprout inhibitors is the cost of use. A significant factor, now that potato prices have dropped due to corona. The average costs for using Restrain are between 3.5 and 5 euros per ton of potatoes for the whole storage season. The variation in cost depends on the insulation measures in your storage. Sprout Inhibition alternatives that require users to fog every three weeks are more expensive. This can easily amount to 5 euros per tonne per three-week treatment.

Training and support

Low costs, the ease of use and low risks of use explain why many growers choose Restrain. If you are considering the use of ethylene sprout inhibition, you can follow a free online training course on the Restrain website. The training prepares interested parties and users for the use of ethylene and the equipment. The training course takes about ten minutes and explains by means of short videos how to use the sprout inhibitor effectively and safely. Topics covered include the pre-start phase, ethylene treatment, storage management and safety guidelines. After correctly answering the test questions, you will receive an official Restrain Certificate. This shows that you are ready to start working with ethylene.

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