Effect of cluster thinning on wine quality of ‘Syrah’ vineyard submitted to double pruning management in Southeast Brazil

Abstract

It is known that in temperate climates cluster thinning improves the quality of the wine. However, there are few studies available about this subject for the tropical vineyards in high altitude with double pruning technique. This technique allows harvesting during the winter time, with full phenolic and chemical ripeness of the grapes. This work aims the evaluation of the cluster thinning. It was evaluated the chemical and organoleptic quality of Syrah wine. The experiment was located in the mesothermal climate and the plants were cultivated under double pruning. This management provided the veraison and harvest of grapes between autum-winter seasons of 2012. The climate was full of driest months and milder temperatures. The plants were submitted to three different treatments T1 (20 clusters/plant – no cluster thinning), T2 (10 clusters/plant – 50% cluster thinning), and T3 (5 clusters/plant – 75% cluster thinning). Although, there was no significative difference on the chemical composition of wine among the treatments. The wine from plants with 5 clusters showed slightly higher total polyphenols, anthocyanins, color intensity, total phenolic compounds and flavanols at bottle filling. This treatment also showed high color intensity after 8 months of aging in the bottles (11.22). The sensorial analysis of the wine showed subtle variation without statistical difference among treatments. However, the treatment 75% cluster thinning showed the highest general appreciation for the global quality. Besides tendencies showed for chemical and sensorial results, the practice of cluster thinning does not improve real quality of those wines. Therefore, this practical it is not indicated for this region.