Medlar seeds, Tree leaves

Medlar Seed Bioplastic

Designer Agostina Laurenzano has endeavoured to collect the medlar seeds that she has harvested from the tree in her own garden and has been able to deduce that those seeds would be rich in starch due to their rubbery texture.

Starch is a polymer which is found naturally in all vegetation as an energy resource for the plant itself. To extract the starch, she has carried out a traditional and ancestral technique, which does not involve the use of energy. Once she successfully obtained the starch, she applied it to a recipe very similar to the one she already used for a potato starch bioplastic. However, she had to regulate the amounts of glycerin, because the medlar seed starch bioplastic was very brittle.

Starches are made up of two carbohydrates, amylase and amylopectin. If the percentage of amylopectin is higher in the composition of the starch, the more rigid and brittle the bioplastic will be. In conjunction to this, aesthetically, this starch brings with it a brownish pigmentation.

Once all the tests of the bioplastic sheets were dry, she was able to observe which one had the optimal elasticity. To regulate this elasticity and prevent future breakage, she decided to reinforce the bioplastic with a completely natural and very abundant resource, the veins of plant leaves.
As more ribs of tree leaves are immersed in the bioplastic gel, the more resistant it will be and the less elastic properties it will retain, but it will retain all its flexibility. With this proposal, the designer invites us to reflect on the abundant amount of resources that we have in front of our eyes.

For her, it is not about accumulating piles of organic waste, it is about studying each of these resources and making the best of them.

If we evaluate this proposal that she makes to us, we reach the conclusion that by planting a medlar tree in the back of our houses we have: a fruit to feed us, from which we will take advantage of its seeds to make bioplastic and dyes, and at the same time leaves of the tree will be our resource to reinforce the bioplastic. And we will be able to obtain different qualities of bioplastics depending on the number of ribs of tree leaves that we embed in it.

The food that the tree gives us and the bioplastic that can also be manufactured, both are completely natural and can be reincorporated into the soil to provide fertilisers and help the good growth of new fruits and leaves.

In this new proposal for a circular economy production, the designer wants to recover the ability to harvest and sow in our homes, to encourage local and proximity production, artisanal production with the recovery of ancestral techniques, care in energy use, and the ability to compost.

Making process

Starch Production:
1-Collect medlar seeds.
2-Remove the skin.
3-Grate them.
4-Place the grated medlar seeds inside a deep container and cover them with water.
5-Let the mixture rest for a day. Stir every two hours with a spoon.
6-Drain the mixture with cotton gauze (the fabric used to drain should not be thick).
7-Save the drained water and let it rest for a day.
8-It will separate into phases, the liquid from the solid. Remove the water, as much as possible, and keep the solid part that is deposited at the bottom of the container.
9-Let it dry completely. As it dries it will oxidise, turning brown.

Rib Production:
1-Dilute 100 gr. of Bicarbonate of Soda with boiling water.
2-Pour this mixture into a litre of water.
3-Immerse the leaves in the water, and put weight on them so they don't float. Leave them for a week in the fridge.
4-Put the leaves and the water to heat and boil for an hour, approximately.
5-Once you begin to notice that the upper skin of the leaf is detaching from the skeleton of the leaf, wait a while longer so that the colour of the surface becomes even. That will mean that the skin has completely shed.
6-Remove the water with the leaves from the fire.
7-Remove the pile with tweezers and a lot of patience, without breaking the rib.

Bioplastic Production:
1-Mix 500 ml. of cold water and 10 gr. glycerin
2-Sift 30 gr. of starch in the mixture, stirring little by little.
3-Heat little by little, stirring without stopping until it reaches 70ºC.
4-Remove from heat.
5-Add 100 ml. of vinegar.
6-Mix everything very well.
7-Pour into a level glass fountain.
8-Submerge the ribs of the leaves of the trees.

Text submitted by the maker and edited by the Future Materials Bank. For information about reproducing (a part of) this text, please contact the maker.