Exploring alternative leaf removal approaches in the context of colour-related phenolics in Pinot noir wine

Within the context of global warming, many winegrowers are already facing the problem of a loss of effectiveness of widely adopted canopy management technique of late (veraison) leaf removal due to the higher temperatures and severe berry skin UV exposure after mid-summer canopy opening. It is known, that too high berry surface temperatures can cause an inhibition of the synthesis in case of pigments responsible for the colour of red grapes and wines. Particular care should be thus dedicated to the varieties known for its genetically derived poor anthocyanin potential, such as Pinot noir (V. vinifera L.). With the aim to seek for a good alternative, the influence of earlier leaf removals (at berry-set and even before flowering) on Pinot noir colour-related phenolics were investigated on grape-to-wine basis in 2010 season and compared to the outcomes of late leaf removal treatments and of untreated (control) vines. Quantitative and qualitative profiles of anthocyanins were analysed by means of UHPLC/TQ-MS as well as the formation of more stable pigments - pyranoanthocyanins were monitored during vinification processes of cold maceration and alcoholic fermentation and finally in the young wines after pressing. The results indicated particularly the novel pre-flowering technique to present a good potential in becoming a solution in case of further global warming manifestation. Known to promote several flavonols and slightly advance hydroxycinnamates in the grapes, earlier leaf removals now show good proportions in the grape anthocyanins, retained also in young wines. Moreover, the promoted formation of several fairly stable red pigments - pyranoanthocyanins was noticed already during fermentation in case of all leaf removal approaches.