The growth and development of the grape berry comprises four stages. The last stage, from the end of berry sugar loading to harvest, strongly influences red wine quality.
In a 2021 collaboration between a commercial Marlborough winery, Nelson Marlborough Institute of Technology, Bragato Research Institute and Plant & Food Research, detailed Pinot noir berry sampling was conducted to determine the end of sugar loading. Three successive harvests (9, 21 and 28 days post-sugar loading) were undertaken in the same block. Both commercial-scale ferments and replicated small-scale wines were made.
Overall quality, typicality, concentration, body, sweetness and flavour intensity were rated lowest in the Pick #1 wine, but not different between Pick #2 and Pick #3. Astringency was highest in Pick #3 while Pick #2 was softest. Wine anthocyanins were 50% higher in Pick #1 while total phenolics were not different between picking dates. Our results indicate that the optimal picking date for Marlborough Pinot noir in 2021 was about 21 days post-sugar loading.
This was presented by Dr Damian Martin, Plant & Food Research, at Grape Days 2024 Central Otago and Hawke's Bay.