Oil palms are an important source of palm oil obviously, but they also contain large amounts of other valuable components such as starch. However, the palm oil industry is also often accompanied by unwanted deforestation, making it less sustainable. That is why Wageningen University & Research is conducting research within the PalmStarch project into extracting starch from the trunks of harvested palm trees. This way the palm oil palm will yield more than oil, while less land is needed for the production of other starch crops, contributing to a more sustainable sector.
Project lead and researcher Ben van den Broek explains why a study like PalmStarch is so important: "The current plantations already exist, forests were cut down for them decades ago. While we cannot reverse this, we can use the plantations much better and more sustainably. One option is to get more out of the whole oil palm, so that less land is needed and deforestation for other purposes is prevented. We are investigating how to do this in this study."
The oil palm at the end of its life
When an oil palm plantation grows old and produces less oil, the trees are cut down and farmers usually leave the trunks on the land. This then serves as nutrition for the soil. This is quite a circular approach, but the effect on healthy soil is limited: nutrients are largely washed away, and sugars and starch decay. Just like a large part of the rest of the trunk. While at the same time there is still value to be gained from the trunks. Using a part of these trunks therefore for other purposes hardly has any negative consequences for the soil, but it does save other cultivation of land and provides useful products.
The value of a palm trunk
Portions of the trunk can be and are already used for veneer production (board material), but it also contains a lot of starch that is now lost. "When you can also extract some starch from the old palm trunk, you don't have to plant another field of cassava or potatoes for starch production, for example," Van den Broek explains. "We estimate that there is about 5 tons of starch in the trunks per hectare. First experiments showed that this is relatively easy to extract, because it is concentrated in the upper part of the trunk, where the content is approximately the same as starch in potatoes." This is not possible, and not needed, for all trunks. Van den Broek: "It is too labour intensive to extract starch from all the trunks. In addition, not all trunks contain the same amount of starch. So you only want to work with the palms that contain the most starch."
Measuring quickly means knowing quickly
But how do you know which palm can be used for starch and which cannot? Van den Broek and his colleagues are developing a measuring device that provides a starch content indication within a few seconds. Van den Broek: "You have to be able to decide quickly: leave it or take it with you?" Avoiding delay is also important for isolating the starch. "If we leave it for too long, the starch is converted into glucose sugars," explains Van den Broek. "Although glucose can still be used to make sugar (gula), starch is more valuable. We are also researching this in the parallel SustainPalm programme."
Effective starch extraction
The project researches the most effective way to extract starch from the palm. That's not easy. Van den Broek: "For example, there is a lot of silica in the palm trunk. This causes the equipment to experience wear and tear more quickly than we would like. Think of knives that become dull." At the end of this project, the researchers hope to have found a solution for this as well. Ultimately, the goal is to develop a mobile factory that produces starch in plantations that are being replanted. This factory can then be moved to a next location.
Harvest locally, use locally
One of the reasons Van den Broek is so enthusiastic about this project is its application. "We can make several products from this starch, such as food ingredients and biopolymers for packaging material. It is also used for breeding insects. How wonderful if, in Malaysia, for example, they can use their own starch for this without additional land demands. But also that we have discovered a new source of starch that has different properties, and therefore also potential for all kinds of new applications."
