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Ms Omarini, What Do You Do With Discarded Citrus Fruit?

Some people put orange peel in their dishwasher because it saves on rinse aid. Others put lemon peel in their wardrobes to fend off moths. There are lots of uses for citrus fruit waste in the home. But Alejandra Omarini thinks on different scales: she wants to make such waste industrially viable.

  • By Jan Berndorff
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Dr Alejandra Beatriz Omarini from Argentina is a Georg Forster Research Fellow at Jacobs University Bremen and Leibniz University Hannover.

Alejandra Omarini
Alejandra Omarini

Every year, over 100 million tonnes of citrus fruit are produced worldwide. About half ends up as waste, like the peel and residues from juice production. “At home in Argentina, where a lot of citrus fruit grows, only a very small proportion of the waste is mixed with animal feed or used to produce energy,” says Omarini. “But even that is a real pity.” Citrus fruit waste contains useful substances, especially terpenes and polyphenols. Secondary plant substances like this are responsible for taste, aroma and colour, they ward off pests, attract beneficials and protect against ultraviolet radiation. The food industry, pharmaceuticals and agriculture are thus all very keen to utilise these substances – as soon as they can be extracted cheaply from plant waste.

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This is what Omarini is trying to do; she experiments on fungi and their enzymes that play an important role in the decomposition of biomass. In her model project, she is growing edible oyster mushrooms on citrus fruit residues. As a result of fermentation after adding a special bacterial haemoglobin a new compound is formed. And this is good for biological pest control. Omarini’s research is still in its infancy. “But if my work bears fruit, we really will be able to make sustainable use of the left overs.”

published in Humboldt Kosmos 109/2018

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