Influence of nitrogen on the biological aging of sherry wine

Nitrogen compounds are essential to the growth and metabolism of yeasts. The uptake and metabolism of nitrogen compounds by Saccharomyces cerevisiae depend not only on the strain and its physiological condition, but also on the chemical and physical properties of its environment. The effect of the addition of different amino acids (L-proline, L-threonine, L-arginine, L-glutamic acid, L-leucine and L-valine) to nitrogen-depleted natural or nitrogen-free synthetic wine on the cell growth, flor velum formation and sherry wine compound production was investigated under controlled biological aging by S. cerevisiae var. capensis strain G1 a typical flor yeast. The formation of flor velum was dependent on particular amino acid, oxygen availability and the composition of wine. Consumption of glycerol was related with the cell growth; in contrast, acetaldehyde tended to be released. Amino acid supplementation resulted in the release to wine of amino acids, esters and higher alcohols. The amino acid which was released in nearly all cases was L-leucine. Addition of L-glutamic acid resulted in the release mainly of ethyl acetate, in the case of L-leucine isoamyl alcohols were released, and for L-valine isobutanol. In the three cases, 1,1-diethoxyethane was released in large quantities. The findings might indicate that the regulation of metabolism succeeds in the most efficient balancing of the redox potential. (c) 2006 Society of Chemical Industry.