Winetech Technical Yearbook 2022

JANUARY/FEBRUARY

SHUTTERSTOCK Cooling Sauvignon blanc grapes before processing – IS IT WORTH THE EFFORT, TIME AND ENERGY?

AN INDUSTRY-FOCUSED STUDY CONDUCTED BY NEW ZEALAND RESEARCHERS ANALYSED THE HOLDING TEMPERATURE OF SAUVIGNON BLANC MACHINE-HARVESTED GRAPES AND THE EFFECT ON THE CONCENTRATION OF GRAPE THIOL PRECURSORS AND THAT OF FREE THIOLS IN THE RESULTANT WINES. 1

I

BY CARIEN COETZEE

INTRODUCTION It is widely accepted that harvesting early in the morning (lower ambient temperatures) and cooling grapes before processing will better preserve the delicate flavours that characterise Sauvignon blanc wines. While there are several advantages to night-harvesting (such as better conditions for the harvesters, increasing efficiency and turnaround in the cellar and energy and cost savings), the exact effect of lower grape temperatures at the start of

processing on the fruity volatile thiols have not been scientifically established. MATERIALS AND METHODS Machine-harvested Sauvignon blanc grapes were collected from a vineyard in the Marlborough region in New Zealand. The grapes were divided into three lots (4 L containers) and stored for two hours in three different temperature-controlled rooms operating at 6, 15 and 24°C, re spectively. After one hour in the tempera ture-controlled room, the lots were mixed

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WINETECH TECHNICAL YEARBOOK 2022