METODI NON DISTRUTTIVI PER IL CONTROLLO DELLA QUALITA' DI UVE BARBERA.

This thesis work was conducted with the aim to tackle two different purposes, both concerning grape quality analysis using non-invasive techniques. The first purpose was to estimate the potential wine production at least one month before the date of harvest. We have evaluated the necessary agronomic and physiological parameters to quantify in advance the production, using a visual assessment form based method. The second objective research, which is the central purpose of this thesis, involved the testing of new non-destructive analysis methods for determining the quality of grapes, in vineyard and in laboratory. In particular, we used two different instruments, a NIR spectrometer (which quantifies the components through exploration of the near- infrared spectral range) with two applications, coupled with chemometric analysis of the spectra acquired. The second instrument is Multiplex3®, which is a portable optical sensor and uses chlorophyll fluorescence to detect shielding substances such as certain phenolic compounds in grape; Multiplex3 ® allowed to monitor the phenolic ripening of the Barbera grapes directly in the field. The most significant part of thesis has concerned the study of the instruments described above, through validation of the results of their application with the data obtained by traditional analytical methods. From this experiment we obtained important results for each of the instruments used. The results obtained confirm the effectiveness and the cheapness of the visual assessment form based method for the prevision of production, but it needs to minimize the different estimation errors for every operator during data collection. Multiplex3® has provided positive results in the measurement of anthocyanins, because it is an accurate, non-invasive and fast tool for the evaluation of grape phenolic content, in addition it is portable allowing the measurement in different places; the experience has confirmed that the better results are obtained through the measurement in vineyard. The device showed better results in the quantification of trisubstituted than disubstituted anthocyanins; it also showed best accuracy utilizing units of measurement such as mg/berry or mg/g of skin, probably because Multiplex3® gets information only from the surface layers of the berries. The NIR spectrometer is a non-invasive tool, it is slower than Multiplex3®, but it allows to quantify more parameters like °Brix, pH and total acidity. The results obtained were positive for both applications of the instrument (fiber optic or autosampler), but in some measurement the output information was different. The fiber optic has shown better results in the evaluation of anthocyanins. In conclusion NIR had the advantage of allowing quantification of flavonols and hydroxycinnamic acids, it is a complete instrument for the visualization of the evolution of quality grapes, but actually it is no portable device. This study emphasises the importance of the research. It is fundamental instrument for the improvement of the grape quality and of all wine industry.