Elaboration of Tempranillo wines at two different pHs. Influence on biogenic amine contents

The aim of this work was to study the effect of pH on biogenic amine formation during the elaboration and conservation (7 months) of Tempranillo wines. Grapes at two pHs (3.4 and 3.7) were vinified to achieve this purpose. After alcoholic fermentation the wines were either inoculated with a commercial malolactic starter or not inoculated. Identification and clonal distribution of lactic acid bacteria and amino acid concentration were determined in an attempt to explain the biogenic amine generation. The results showed that the pH of the must influenced the clonal distribution of the Oenococcus oeni strains which conducted the malolactic fermentation and also the concentration of amino acids in the wines after alcoholic fermentation. These aspects could account for the higher biogenic amine formation in wines with the lowest pH during malolactic fermentation. In these wines, inoculation with a malolactic starter was favourable since it produced a lower biogenic amine concentration after malolactic fermentation. Furthermore, the pH also influenced the concentration of amino acids after malolactic fermentation and the lactic acid bacteria distribution during the conservation of the wines. These aspects allow explaining the greater formation of histamine, tyramine and putrescine in the wines with the lowest pH vinified via lactic acid bacteria inoculation after seven months of conservation.

► The pH influenced the distribution of lactic acid bacteria. ► The pH affected the amino acid concentrations. ► There were higher levels of biogenic amines in wines with the lowest pH.