The Australian Wine Research InstituteThe Australian Wine Research Institute

Slow and stuck fermentations are often associated with sulfide formation. This new analysis is available to provide wineries with information about the nitrogen status of their juice and to avoid or minimise nitrogen related fermentation problems. The analysis will also provide information that will allow wineries to determine optimum additions of di-ammonium phosphate (DAP).

YAN is measured in two steps using the Randox Daytona enzymatic analyser, as total nitrogen cannot be quantified by measuring only ammonia. The first step involves measurement of alpha amino nitrogen. It does not detect secondary acids such as hydroxy proline or proline (which is not utilised by yeast), nor does it detect ammonia. The second step determines the amount of ammonia present. The two measurements together enable YAN to be calculated.

Samples must be submitted for this analysis in plastic containers and frozen prior to despatch. Samples that have commenced fermentation will not give accurate results.

For further information on yeast assimilable nitrogen, please refer to Institute publication # 587 (Weeks and Henschke 1999).