Microbiological stability

Measures to ensure microbiological stability have to counter the growth of either yeast or bacteria. The simplest way to avoid yeast growth, which could result in a second fermentation, is to ensure that the wine is free of fermentable sugar, and that its residual sugar is negligible. If some residual sugar is necessary to balance, say, high acidity in the wine, then sterile filtration and sterile bottling are the surest way of guaranteeing stability. Failing the necessary equipment and trained personnel, additions of sulfur dioxide and sorbic acid will sufficiently inhibit most yeast growth, at some marginal depreciation of wine quality.