Dry ice in the containers results in better quality red fruits
Transportation and quality are often a challenging combination. A good product can arrive in Europe as a poor quality product after several weeks at sea. Several options can be used to preserve product quality, and Wageningen Food & Biobased Research has recently added a new option: dry ice as a source of high levels of CO2 for the transport and storage of berries. Now a partner is needed to market the product.
“We wanted to create a high CO2 content in the transport container, refrigerated container or truck to protect the product against spoilage,” says Eelke Westra, post-harvest technology researcher at Wageningen Food & Biobased Research. We are looking for an alternative to SO2, CO2, for which we are also looking for a way to easily keep it at a high concentration with the use of dry ice. It is mainly about protecting against mold or other quality defects that can be prevented with a high level of CO2.
High content of CO2 as an alternative to SO2
The Dutch research team responded to the demands of an alternative to CO2 for the market. To transport grapes, increasing the CO2 in the container is relevant to combat the Botrytis. 'SO2-impregnated pads are used for this purpose, but there is a possibility that Europe will ban their use. Also, some people are allergic. It is for these reasons that we received the request for an alternative,” says Eelke. Another disadvantage of SO2 pads: when the dose is too high, the fruits are damaged, as the fruit loses color. "That was the reason we investigated the high CO2 content in the containers, and since we already knew that dry ice could be useful, we also took that into account during the study."
The conventional method of creating a high level of CO2 in a container is to first use nitrogen to dissipate oxygen, after which the CO2 expands in the container. The container must be manufactured resistant to gases, "and we expect that the CO2 content in the container will remain high throughout transport, since the containers do not have CO2 cylinders." The researchers chose to look for a source of CO2 in the container. “Products breathe, but not all products produce enough CO2, which is why you need a source in the container,” explains Eelke. A CO2 cylinder could be a solution, but dry ice, the solid form of CO2, is another option. It is also an affordable option, estimated at around 200 to 400 euros per container.
Grapes, currants, cranberries ...
But what is the advantage of dry ice compared to a CO2 cylinder? “It can be placed in the container at the beginning of the supply chain, so you don't have to wait until the container reaches the place where the cylinder is located. Because of this, the trajectory with a high level of CO2 is longer,” says Eelke. Furthermore, the impermeability of the container becomes less decisive. Containers are assumed to be airtight, but are verified as standard. “We haven't investigated it either, but we know that the desired CO2 concentrations are not always achieved,” she continues.
Although the research was based on grapes, other products, such as currants and blueberries, are also transported using high levels of CO2. Some types of fruit respire more than others and emit a lot of CO2, being able to generate around 20 percent of the CO2 content that way. "The product produces its own CO2," explains Eelke. Grapes and blueberries do not respire enough to reach a high percentage. "A controlled atmosphere container does not generate CO2, so an alternative source is needed."
"The study mainly focused on the technical aspect of keeping the CO2 level high for longer periods." Depending on the amount of dry ice placed in the container, the container could have high CO2 levels for two to three weeks. The study was completed a year ago and a patent was applied for. “The grape importers we work with are primarily interested in quality,” concludes Eelke. «They will not market the product, but they do want to use it. “The project is in a development stage and we are looking for market participants, such as logistics service providers, who want to work with us to commercialize the service.”
For more information:
eelke.westra@wur.nl
paul.goethals@wur.nl
www.wur.nl/wfbr
Previous article
Ukraine in 2019 will double exports of blueberriesARTÍCULOS RELACIONADOS
