Metodi ottici non distruttivi per il monitoraggio della maturazione in uve a bacca colorata.

Non-destructive and fast monitoring of berry ripening is one of the challenges of research in viticulture. The evaluation of berry ripening through polyphenol accumulation is traditionally based on expensive and time-consuming analytical techniques; furthermore, sampling is a critical step in viticultural applied research, being known that berry phenolic composition and evolution depend on a number of factors, such as environment, viticultural practices, vine to vine, cluster to cluster and berry to berry variability. To reduce the effects of this wide heterogeneity over sampling variability, it would be necessary to amplify the entity of sampling, which is not always possible due to limited money and time resources. The optical portable sensor Multiplex® (ForceA, Paris, France), able to estimate some classes of polyphenols in seconds, thus working on a very wide number of clusters, has been used to estimate the evolution of anthocyanin accumulation during ripening and at harvest in Vitis vinifera cv Barbera over two years. To this aim, in 2008 and 2009 the evolution of anthocyanin accumulation was studied in berries of a vineyard located at Agliano, Camporotondo (AT) by the simultaneous determination of total anthocyanin by Multiplex® measurements and wet chemistry analysis (by spectrophotometry); besides, to increase the number of data, Multiplex® measurements, samplings and analysis were repeated at harvest on berries from further Barbera vineyards, whose production was known to be very different as to grape quality (from very low to very high anthocyanin amount accumulation). The calibration of Multiplex® indexes ANTH_RG and FERARI against wet chemistry analysis was done; the Multiplex® measurements were carried out on intact berries in the vineyard. Equations obtained from calibration curves, chosen if they could provide a univocal prediction of the anthocyanin content, can be used in the vineyard to estimate the berry anthocyanin content in a fast and non-destructive way. The relation between ANTH_RG and wet chemistry analysis was represented by different equations: a linear curve, a second degree curve and an exponential curve; in cv Barbera the exponential curve was the most suitable, as it did not produce negative results for concentrations higher than 2000 mg/kg of anthocyanins. The FERARI index showed a satisfactory predictive capacity of total anthocyanins, displaying a linear relation with wet chemistry analysis data up to 1300 mg/kg of berries.