Evolution of malolactic bacteria and biogenic amines during spontaneous malolactic fermentations in a Greek winery

Abstract

To study the population dynamics of indigenous malolactic bacteria in a Greek winery and to examine their potential to produce detrimental levels of biogenic amines (BA) under winemaking conditions. Although the wines studied were of different vintage, grape variety and enological characteristics, molecular typing of malolactic bacteria revealed only a low number of strains within the single-species populations of Oenococcus oeni that developed during spontaneous fermentations. Strain MF1, originating primarily from the vineyards surrounding the winery invariably predominated in almost all samples. HPLC analysis showed a slight increase in the BA, putrescine, tyramine and phenylethylamine after malolactic conversion, while histamine, methylamine and ethylamine remained unaffected. No correlation could be established between the BA profiles and the bacterial compositions or the amino acid concentrations in wine samples studied. A certain regional bacterial flora is established in the winery that prevails in spontaneous malolactic fermentations (MLF) irrespective of the wine characteristics. In all cases, the BA content of the wines after malolactic conversion was within enologically acceptable levels. This is the first report on the malolactic bacteria occurring naturally in spontaneous MLF in Greek red wines and a preliminary assessment of their impact on wine safety in relation to BA.