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Product and process innovation for the citrus

The project concerns: citrus juice quality improvement and the production of valuable by-products; the extraction, recovery and characterization of essential oils; the use and upgrading of waste material. These areas have both quality and economic dimensions and are essential for a dynamic forward-looking citrus industry.

Use is being made of tangential filtration and enzymatic treatment to obtain special clarified lemon juices to be used as acidulants and as an alternative to the additive E-330 (ie citric acid) in a wide range of foods. Resins are being used to remove the bitter compound (limonine) and the resins are being tested on a pilot scale. Anthocyanins are being recovered (by passing red juice through a resin) for use as colourants in jams and carbonated beverages.

Supercritical carbon dioxide extraction of citrus essential oils from part of the citrus tree gave new extracts with potential applications, in particular for perfumery purposes. The amount of oxygenated compounds (linalol, decilic aldehyde, neral, geranial) in 'cold pressed' essential oils was concentrated ten-fold by the use of supercritical carbon dioxide. This level of recovery is essential for commercial success. Tests are also in progress on minimizing the oxidative changes taking place during the recovery of essential oils from water/oil emulsions coming from the first stage of centrifugation of 'cold pressed' essential oils.

A bioclimatic chamber has been constructed for the semi-solid fermentation of fresh citrus wastes for the production of microbial biomass. As a result, protein enrichment of fresh orange peel can be achieved by Trichoderma a1, Tr. reesei and Phanerochaete chrysosporium. In other tests, proteolytic enzymes have been produced from a citrus pectin medium by Rhizopus nigricans, while valuable flavonoids such as naringin are being obtained from spent citrus peel.


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