Grape Days 2024 | Grape sugar loading & harvest date implications for red winemaking | Damian Martin

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.