Nitrogen supply: availability in the must

The standard

A measured nitrogen supply quantifies the yeast-available nitrogen before fermentation instead of estimating it from the sugar content. Only the measurement separates a deficit from an excess.

Criteria

• What is recorded is the yeast-available fraction, not total nitrogen
• The measurement precedes the start of fermentation, it does not follow it
• A threshold marks where fermentation begins to stall
• An excess remains a risk, not a reserve

Distinction

Nitrogen supply ≠ nitrogen assimilation: supply is the availability in the must, assimilation the uptake by the yeast. Nitrogen supply ≠ lees ageing: lees ageing acts after fermentation, the measured nitrogen supply stands before it.