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Summary

An Italian research centre gathered large experience in the application of a non-invasive optical sensor, based on the measurement of chlorophyll fluorescence, to control fruit quality. Ripening of winegrape was followed directly in the field detecting the accumulation of phenolic compounds such as flavonoids and anthocyanins. Quality of other fruits was monitored in post-harvest. It is looking for partners for common RTD projects and SME interested in testing the devices.

Full description

Fruit ripeness can be monitored in a non invasive manner by using a new optical method based on the measurement of chlorophyll fluorescence. The method was successfully applied by an Italian research centre (in collaboration with French researchers) to evaluate the maturity of olive and grape fruits. The new maturation indices are more accurate than those actually used. The technique applies to portable devices for in field detection, and to on-line post-harvest sensors for fruit control and sorting.
Spectroscopic techniques are rapid and non-destructive, and therefore are suitable tools to assess the quality of fresh fruits. It has been proved that the degree of maturity that is related to the pigment content of the fruit can be determined by fluorescence measurements. The proposed method is based on the detection of chlorophyll fluorescence from the fruit surface induced by suitable excitation wavelengths. The intensity of the emission light is affected by the presence on the fruit surface of compounds such as carotenoids, anthocyanins, and polyphenols in general: the higher the compound concentration, the lower the chlorophyll fluorescence. Comparing this value with a reference one permits to estimate the compound concentration, which is related to fruit maturity.
The method has been tested with success on olive and grape fruits.
According to the present method low-cost optoelectronic systems have been developed, consisting of LED (light emitting diode) light sources, providing different excitation wavelengths, photodiode detectors and optical filters. Other devices improved to perform fluorescence imaging of the fruit surface in order to add a further parameter of control, which is the pigment distribution on the product surface, are under development.
Partners sought: 1) Research centres for RTD projects. 2) Fruit producers, olive oil or wine producers wishing to characterise their products with a new quality index.

Innovative Aspects

The proposed method is more sensitive and precise in measuring pigment concentrations in fruits in a non-invasive manner compared to other available methods based on light reflectance measurements.
The method represents a rapid and non-invasive tool for monitoring fruit ripeness particularly suitable for on-line and in situ monitoring.

Fluorescence-based sensors can easily be integrated into already developed monitoring systems, which provide complementary data for quality control.

Partner expertise sought:

- Type of partner sought:
1) Research centres for RTD projects.
2) Fruit producers, olive oil or wine producers wishing to characterise their products with a new quality index

- Specific area of activity of the partner
1) Horticultural science; post-harvest physiology; biospectroscopy.
2) Commercial fruit growing; olive oil and wine production; agro-food industry.
3) Post-harvest machinery; agro-food industry.

- Task to be perfomed
1) Give competence in optimising the method to control specific products.
2) Supply product samples to test the method and related devices.