Harvesting ice wine grapes, concentrated sweetness at below zero temperatures

“Ice wine” is popular for its condensed sweetness, and ice wine grape harvesting began early in the morning on December 20 at an Ikeda Grape and Wine Research Institute field in the Tokachi region. Amidst the harsh coldness of 13 degrees below zero, 16 workers carefully picked grapes of the original Ikeda “Yamasachi” grape variety.

When these ripe grapes go through a process of freezing and drying on the vine, water content in the grapes is dissipated, and the sweetness level rises to 40 degrees Brix or more, about twice the normal grape sweetness. In order to harvest frozen grapes, picking must start before sunup on mornings ideally 10 degrees below zero.

On this morning, workers harvested approximately 700 kilograms in 2.5 hours. The grapes were immediately pressed and juice was extracted. The sweetness level was 47 degrees Brix. The production section head commented, “We were able to harvest the grapes at just the right time. This will make wine with a rich sweetness.”

The field for this winter is 80 ares, which is 30 ares larger than last winter. Grapes were harvested twice in December of last year, with a total of up to two tons pressed. Sales are slated for December of 2022. Last winter was warm, delaying the harvest until January of 2021. Because that yield occurred in 2021, the same year as this season’s yield, the 2021 ice wine that will start selling around January and February of this year will be designated as originating from the “previous year’s crop” to distinguish them from this season’s wine.

Harvesting ice wine grapes in the severe cold (around 5:45 a.m. December 20 in Kiyomi, Ikeda)


Ikeda Grape and Wine Research Institute field