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A.R. GUTIÉ RREZ, P. SANTAMARÍA , S . E P IF AN I O, P. G AR IJ O AN D R . LO PE Z . 1999. The ecology of spontaneous fermentation in a new winery in La Rioja (Spain) was studied during 5 consecutive years using mitochondrial DNA restriction analysis. The number of different strains detected for each vintage and their appearance frequency varied from one year to another. A small number of strains were present in consecutive years, but the presence of each one varied in function of the specific year. Only one strain was present in all the 5 years studied. For the 1997 vintage, an unusual dominance of non-Sacharomyces yeasts in the vigorous fermentation was detected; this may explain the abnormal analytical data for the wines of that year.

Malolactic fermentation (MLF) of Tempranillo Rioja wines (Spain) inoculated with two lactic acid bacteria (LAB) strains were studied and compared with spontaneous MLF. Inoculation with selected Oenococcus oeni lyophila shortened MLF duration up to 19 days and lead to wines with more fresh and fruity characters, especially when implantation was 100%. We demonstrated modifications in the concentration of volatile and nitrogenous compounds and a good correlation between analytical and sensory attributes was also noted. In addition, the low initial amino acid concentration and the consumption of these compounds by the inoculated yeast strain during alcoholic fermentation resulted in wines with very low biogenic amines levels (under 3.75 mg L )1 ) after MLF and 3 month storage period in all cases. The results showed the significance of choose the most suitable starter to elaborate quality wines and suggest the control of amino acid content in must and wine to prevent the formation of biogenic amines.

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