Effect of biological ageing of wine on its nitrogen composition for producing high quality vinegar

• The new approach of using biological aged wine as substrate for vinegar production is studied.
• Initial nitrogen content sources suffice for the three necessary bio-transformations.
• The microorganisms involved in the series stages adapt themselves to available nitrogen sources.
• The problem of urea formation in wine ageing was suppressed by the acetification.
• Though a specific product is studied it is an example with a broader interest.

There is increasing interest in producing novel high quality vinegars. In this work, we examined the effect of biological ageing of white wine on its nitrogen composition (viz. amino acids, urea and ammonium ion, which constitute the main sources of nitrogen for acetic bacteria during the acetification process) with a view to confirming the suitability of aged wine for producing quality vinegar.Available nitrogen contents in biologically aged wine were lower than in young (unaged) wine; this resulted in a slightly lower acetification rate and production with the former. The nitrogen composition of the two vinegars was very similar, with l-proline and l-cysteine as the major amino acids. By exception, only the vinegar from the young wine contained ammonium ion. The ageing process by flor yeast produces urea which is eliminated by the bacteria in the next stage.Available nitrogen for use by acetic bacteria in biologically aged wine is seemingly no limiting factor for acetification. The problem posed by the formation of urea during wine ageing was suppressed by the subsequent acetification process. The study could be an example of how different microorganisms use the available substrate in serial biotransformations.